May Gardening Checklist

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May Gardening Checklist

Fellow Gardeners,

The information, dates and techniques in this are as accurate as I can currently offer.  During the past three decades I have cared for, nurtured and observed tens of thousands of plants.  With the help of many gardening friends I have attempted to offer on these pages some useful information to help you with your own garden. Gardening is sharing.  Any corrections, comments or suggestions are appreciated and will improve future information.

annuals, sweet peas, wildflowers, cool-season, gardening, garden, petunias, lobella, verbena, marigold, ageratum, cosmos, impatiens, coleus, torenia, begonias, dahlias, zinnias, flowers, bedding plants

Annuals:

  • (See also Sweet Peas and Wildflowers)
  • This is definitely a month for planting warm-season annuals.  The nights are consistently warmer, the days are longer sunnier and the thermometer is rising.
  • Warm-season annuals should are in abundant supply and in all sizes right now.  Get them planted now, before it gets too hot.  They will establish a bit easier now than they will in July or August and irrigations will be a bit easier also.  Choices include petunias, lobelia, verbena, marigold, ageratum, cosmos, impatiens, coleus, torenia and begonias.
  • If you need some real hot weather sizzlers try dahlias, zinnias, gomphrena, cleome, portulaca and lisianthus.  These absolutely love the heat.
  • Because of their quick growth and heavy flowering potential, annuals need more fertilizing than most other plants in the garden.
  • Keep deadheading (removing spent flowers) from annuals to help them continue blooming abundantly.
  • Plant hot-weather annual summer vines from seed now.  These include Morning Glory and Moonflower.

avocados, mature avocado tree, tree, feeding, healthy, food, planting, plant, mulch, irrigate, gardening, orchard

Avocados:

  • Avocados are still growing well right now and the plants should look at about their healthiest of the year.
  • Irrigate as needed to keep the soil moist, but not wet.
  • Most varieties will still not have fruit ready for harvest this early.  However, some varieties, like ‘Gwen’ and ‘Whitsell’ often have fruit at unusual times.
  • This is a very good month for planting avocados.  Being sub-tropical plants, avocados prefer to be planted at the beginning of the long warm half of the year.
  • Don’t be alarmed by a lot of leaf drop on mature plants.  Avocados produce a lot of leaf litter nearly year round.  This is a normal condition.
  • Be sure to keep a very thick blanket of mulch, compost or fallen leaves under mature avocadoes at all times.  Avocadoes need a cool root-run for good health.

azaleas, flowers, over watering, hybrids, gardening, garden, dormant, bloom, plant, pink, pruning

Azaleas:

  • Most varieties are about finished blooming now, however a few are summer bloomers.
  • A light application of an acid fertilizer, like cottonseed meal, is good now as they enter into their “growth” season.  In the ground, only two feeding per year are necessary.  Your next feeding will be in September.
  • Never cultivate under an Azalea or you will damage their delicate surface roots.  A thick layer of organic mulch is a better idea.
  • They don’t really require any pruning, but if you do need to shape them or reduce their size a bit as soon as they finish blooming is the best time to do it.

bearded iris, flower buds, flower, blooming, well-balanced, organic, fertilize, insecticides, flower stalk, foliage

Bearded Iris:

  • Most bearded iris are now in full bloom or a few may have already even finished this flower cycle.
  • If you are growing any of the new “repeat-blooming” varieties they may cycle again in as little as a month or two.  Keep feeding these re-bloomers aggressively.  Older “once-blooming” varieties can have their feeding reduced in half.  Any fertilizer labeled for roses (by not with insecticides or other added ingredients) will do fine.
  • Trim off the faded flower stalk just above the foliage when the last flower fades.
  • If you need to add more iris to your garden you can still do it now.  Select blooming plant now and plant them.  Just be careful not to disturb to system too much.

beneficial insects, wildlife, giant whitefly, gardens, parasites, predators, lantana, pesticides, lizards, frogs

Beneficial Insects:

  • Eugenia Psyllid (Trioza eugeniae) populations will begin coming under control now by a tiny, stingless, parasitic wasp.  Do not spray Eugenia’s; the wasp will do an adequate job.
  • Beneficial insects should be abundant in your garden now, especially if you planted a few flowers just for them.
  • Ladybugs and Lacewings can be released again this month.  Two or three releases of both ladybugs and lacewings in the spring can reduce many pest populations significantly, very possibly eliminating the need for pesticides.  This is the last of your spring releases of these beneficials.
  • Remember that the population of natural predators and parasites always follows behind that of the pest.  If predators are present in your garden, even in small numbers, they will need some time to catch up with the pest.  Be patient.
  • Giant Whitefly is active again and infestations should be noticeable.  Predators and parasites should also be present by now, but remember, they will usually be a month or so behind the whitefly population.  Check immature whiteflies carefully for indications of parasites.  If none are found in one part of the garden remove a few leaves from another plant that has been parasitized and place it carefully into the foliage of the non-parasitized plant.
  • Remember that the population of natural predators and parasites always follows behind that of the pest.  If predators are present in your garden, even in small numbers, they will need some time to catch up with the pest.  Be patient.
  • Flea, grub and cutworm populations may begin showing up now.  Control can be achieved by using various beneficial nematodes.  These microscopic worms are applied by mixing them in a water can and drenching the area, then watering well.
  • Trichogramma wasps are very effective parasites of caterpillars.  If these pests are usually a problem in your garden a couple of releases of these beneficials will be worthwhile.  Space the releases 30 to 45 days apart.

bulbs, rhizomes, tubers, hyacinth, ranunculus, cyclamen, spring bulbs, gardening, garden, planting, dahlias, flowers

Bulbs, rhizomes, tubers, etc:

  • (See also Bearded Iris, Dahlias, Cannas and Tuberous Begonias)
  • The big burst of spring flowering bulbs is now transitioning into warmer weather species.  Bulbs that will likely be in flower now in Orange County include some alliums, bletilla, calla, gladiolus, hippeastrum, some true lilies, ornithogalum, sprekelia, tigridia, tritelleia (highly recommended) and watsonia.
  • As spring bulbs finish blooming do not hurry to cut back the foliage or ignore the plant.  Keep the leaves in place and continue watering until the leaves naturally turn brown and dry, then you can cut them off.  These leaves are sending energy to the bulb for next season.  Of course, for one-year bulbs like most anemone, crocus, hyacinth, muscari, ranunculus and tulips, after they are done blooming, pull them and toss them out.
  • Bedding cyclamen have been blooming for months but are about done in most gardens.  Most gardeners pull them out, however, if they are in good, rich soil and protected from summer heat and dry winds they will struggle through the summer and return to flower this fall.
  • Caladiums that were planted recently are now beginning to sprout.  These love warm soil, warm nighttime temperatures and long days but not direct sun or wind.
  • Plant new tuberose tubers now or re-plant those that you lifted last November and have had in storage.

california native plants, native plants, blooming, flowers, summer, native

California Native Plants:

  • A few California natives will still be blooming and growing, but most will already be slowing down and preparing for the long, hot and dry summer months.
  • Be very cautious irrigating most of our native plants during the summer.  Most of these are adapted to a winter wet – summer dry moisture cycle.  Too frequent irrigations now (especially in soils with a clay content) will certainly cause problems.

camellias, japanese camellias, bloom, petal blight, fungal disease, petals, flowers, shaping, pruning, fertilize

Camellias:

  • A few Japanese Camellias may still be in bloom.  As soon as your camellia finishes blooming do any shaping or other pruning to the plant.
  • You should be at the beginning, middle or end of your camellia fertilizing for the year.  Apply the first of three feedings to your camellia about 4-6 weeks after it finishes blooming.  Use an “azalea/camellia” or acid based fertilizer, like cottonseed meal.  Apply a light application (camellias are not heavy feeders) evenly around the base of the plant, but do not dig it into the soil.  The second feeding is 4-6 weeks later and the final feeding will be 4-6 weeks later again.
  • This is a good time to apply a fresh, thick, organic mulch under your camellias.  This mulch will keep the roots cooler during the warm summer months, improve the soil quality and reduce watering requirements.  Carefully rake up any fallen flowers and, if fertilizing this month, apply the fertilizer first and put the mulch on top.

cannas, flowers, fertilizer, organic, gardening, garden, plant

Cannas:

  • The first flowers should be on them now.
  • Keep them well watered, cannas do not like dry soil.
  • As cannas flower you may notice that each stalk produces a cluster of flowers at the top.  After this cluster finishes the stalk grows a few more inches and produces another cluster.  In some varieties, this can go on for four or five clusters and last almost two months from beginning to end.  When the last cluster of flowers has finished, cut the entire stalk to the soil.  This stalk will never bloom again and cutting it down will encourage more stalks, and flowers, to grow.  Keep this process up all summer for the best results.

citrus, fertilizing citrus, honeybees, fruit, earth, organic, lemons, limes, ripe, kitchen garden, farming, harvest

Citrus:

  • Citrus are growing well this month and a few may even have some flowers on them.
  • Continue fertilizing this month and every month from now until July.  Use a fertilizer that is rich in such trace minerals as iron, zinc, manganese, copper and others.  These ingredients are usually well represented in organic fertilizers like Dr. Earth.
  • Honeybees are pollinators for citrus.  Encourage these beneficial insects and avoid anything that might discourage them.
  • Be attentive to irrigations now that the weather is warming up.
  • Kumquats should be ripe now.
  • ‘Kara’ tangerines may be ripe by now or very soon.  This about the only summer bearing mandarin and needs a warm inland location.  Tangelos may also be close to ripe.
  • Valencia oranges may look like they are ready to harvest but probably will not have developed their sugar content yet.  Resist the temptation to pick them this early and let them sit on the tree for another month or two to develop a higher sugar content.
  • If ants are crawling up the trunk of the tree apply Tanglefoot (a sticky, waterproof substance) to stop them.

clematis, flower, vine, organic fertilizer, purple, bloom, grow

Clematis:

  • Along with April, this will be the heaviest blooming month for most clematis.  Keep feeding them with a balanced organic fertilizer to keep them going.  If your soil is slightly alkaline (high pH) periodically alternate fertilizing with an acid product such as Cottonseed Meal.
  • Keep the roots cool and shaded wherever possible, but not the tops.  Planted a small shrub or a couple of perennials just to the south side of the roots will help.  In addition, apply a very generous organic mulch over the surface of the soil.
  • Keep plants well watered.

dahlia xxl, dahlias, designer dahlias, dormat tubers, foliage, organic, fish bone meal

Dahlias (tuberous types):

  • Tubers should be growing well now and the early varieties will be setting buds and maybe even blooming.
  • For younger plants be sure to pinch off the top set of leaves when the stems are about eight or ten inches out of the ground.  This will encourage the plant to branch and have more blooms.
  • If you haven’t already put stakes in for the taller varieties, do so right away.  Natural cane bamboo stakes work well.
  • Fertilize dahlias regularly throughout their growing and blooming period.  Use a liquid or granular organic fertilizer that is low in nitrogen and high in phosphorus.  Fish Bone Meal is excellent.
  • Regularly cut off spent blooms to make the plants both look better and set more flowers.
  • Keep the taller varieties carefully staked to prevent the heavy canes from toppling over.  Heavy natural cane bamboo stakes work well.

deciduous fruit tree, apple, apricot, peach, plum, fruit tree

Deciduous Fruit Trees:

  • As the weather warms, be sure to monitor the soil moisture and irrigate as needed.
  • Several varieties of tree will “drop” a lot of their fruit about now or next month.  Don’t be alarmed; this is normal, since the tree cannot usually support all of the fruit that it originally sets.
  • After the “drop” is completed is the best time to thin any remaining fruit.  Emotionally, this is one of the most difficult things for a gardener to do and therefore often avoided.  However, well-spaced fruit will develop into a higher quality crop and the fruit size will be larger as well.

ferns, sword ferns, chain ferns, maidenhair, fertilize, cottonseed meal

Ferns:

  • This is a good time to plant, re-pot or transplant ferns.  Just keep them well watered.
  • Still a good time to re-mount and/or divide staghorn ferns that have outgrown their boards or pots.
  • Most ferns are now growing well and enjoying the warmer weather.
  • Continue fertilizing.  Use a mild, organic fertilizer on ferns and alternate periodically with an acid type, especially in high pH soil.  For most common varieties try blood meal alternated every third feeding with Cottonseed Meal.
  • If you haven’t already, consider removing old, dry or tired looking fronds all the way to their base.  Some varieties like sword ferns, chain ferns, autumn ferns, rabbit-foot ferns and other rhizomatous varieties can be revived by cutting all of their fronds nearly to the soil.  New growth will quickly reappear.
  • Irrigate most varieties regularly according to weather and the growth of the individual plants.
  • Continue fertilizing mounted and containerized staghorn ferns with a mild, liquid fertilizer.  Fish emulsion is excellent.
  • Check for pests.  Scale can be a problem on several varieties and often goes undetected.  It is often closely associated with ants, which need to be controlled as a part of any treatment program.   On other ferns, especially staghorns, check carefully for early signs of spider mites.

fertilize, flower food, plant food, plant

Fertilize:

  • (See also the information under the individual plants)

fuchsias, flowers, shade, flowering, grow out, fertilize, well watered, garden, gardening, gall mites, pest

Fuchsias:

  • Your plants will be in full bloom now.
  • Keep fertilizing regularly with a balanced fertilizer or one slightly higher in phosphorus, to promote blooms.
  • Keep the plants well watered, especially during a warm spell and any plants in hanging baskets.
  • Groom the plant periodically by removing dead flowers and any developing seedpods.
  • Watch for Fuchsia Gall Mites, which are a serious pest of these plants.  Look for any signs of puckered or distorted new growth.  If you discover any, pinch it out and dispose of it immediately.  A pesticide treatment is usually required.

gardenias, blooms, fertilize, minerals, organic, flowers, garden flowers, flowers

Gardenias:

  • Gardenias should be budding and blooming well this month.
  • Keep them well fed through the summer months.  Use a fertilizer with trace minerals, such as most organic types and alternate this with an acidic formula to keep the pH down.
  • If the leaves are showing signs of green veins with yellow areas between the veins, especially on the new growth, they need additional iron.  Iron is a supplement to the  regular fertilizing program of your gardenia.

geraniums, ivy geraniums, scented, flowers, zonal, fertilize, prune back, martha, leaves, rust, springtime, blooms

Geraniums:

  • This group includes Ivy geraniums, Zonal geraniums (also called “Common” geraniums), Martha geraniums and the various scented geraniums, but does not include true geraniums (sometimes called “Hardy” geraniums), which are discussed under Perennials.
  • Ivy and Zonal types should be blooming well now.  Remove spent flowers to the bottom of the stem regularly to encourage more blooms.
  • Martha types should continue to be blooming well.  Regularly remove spent flower clusters just below the flower to encourage more blooms.
  • Ivy and Zonal geraniums do not like heavy pruning.  To keep the plants shapely and vigorous for a longer period of time prune back a few long stems every month or so from now through fall, but never very many at one time.
  • Fertilize all geraniums, except most scented types, regularly with a balanced fertilizer.  Geraniums prefer a slightly acidic soil, so periodically alternate feedings with an acid fertilizer, such as Cottonseed Meal.
  • Rust may continue to be a problem in some gardens, especially on Zonal and Martha varieties.  However, it is usually only a springtime issue and with the warm weather approaching should be about over.
  • Budworms may still be attacking the developing buds and new leaves.  If necessary, spray with BT on a regular basis.

grapes, grapevines, growing grapes, organic, fertilizer, kitchen garden

Grapes:

  • Grapes should still be growing vigorously now.  Direct the canes as desired.
  • The first application of fertilizer should have been made when the new growth had grown a couple of inches.  Assuming the use of a granular organic product, the second application should be six to eight weeks later (about now), the third application another six to eight weeks later and the final application in another six to eight weeks.. Remember, use a well-balanced product that contains trace minerals, which grapes need.  Organic products usually are a good choice.
  • Irrigate regularly and deeply according to the soil and temperatures.

groundcover, cool season groundcovers, california native plants, ceanothus, mazanita

Groundcovers:

  • Cool season groundcovers are still blooming, but the heat will soon catch up with them, especially in warm inland gardens and on south facing slopes.
  • Warm season groundcovers have waking up and are growing again and possibly blooming as well.  If you didn’t last month, feed these now with a balanced, organic granular fertilizer.
  • This still a good time to perform a heavy cutting-back of warm-season varieties.  Many groundcovers build up considerable thatch and loose their vigor if not cut back periodically.  Hurry to get this chore done now, before the weather heats up too much more.  Be sure to fertilize after the cut-back, to insure quick recovery.
  • California native groundcover plants, like Ceanothus and Arctostaphyllos (Manzanita) may still be showing some blooms.  Although tempting, this is not a good month to plant these.  Wait until late this fall.
  • Although getting late, large scale groundcover plantings can still be accomplished now.  Be sure to mulch between the plants after the planting to help the plants establish, reduce weed growth, improve soil quality and reduce irrigations.
  • Step up irrigations as needed, especially in sunny areas or on slopes.

herbs, herb garden, warm weather, grow, basil, oregano, rosemary, sage, thyme, catmint

Herbs:

  • This is still a great time to plant basil.
  • Many perennial herbs can be planted nearly year-round, but are particularly well suited to spring planting, since they thrive during the warm summer months.  These include marjoram, oregano, rosemary, sage, thyme, catmint, catnip, chamomile, comfrey, feverfew, lavender, lemon balm, lemon grass, lemon verbena, St. johns wort, tansy, tarragon and thyme.
  • Plant the annual “summer savory” now in the warm weather.    The perennial “winter savory” can also be planted now, however the flavor of the perennial version is generally considered inferior.
  • This is still a good time to rejuvenate certain old or tired herbs by giving them a hard trim.  These include chamomile, chives, garlic chives, lemon balm, lemon grass, marjoram, mint, oregano, salad burnet, sorrel, St. johns wort, thyme and watercress.  All of these can be scalped almost to the soil line and, with fertilizing, will recover quickly.  Other herbs like catmint, catnip, feverfew, lemon verbena, rosemary, rue, sage and tansy should be cut a bit higher.  Cut lavender only very lightly.

hydrangeas, hydrangea, new growth, flowering, feed, prune, slufate soil

Hydrangeas:

  • These should be growing nicely and most will even be blooming.
  • Apply a moderate feeding.
  • Do not prune hydrangeas at all this time of the year.  Hydrangeas bloom on one-year-old stems.  Pruning now will eliminate most of the flowers.
  • If you want to try to get blue or lavender flowers on your otherwise pink plant you should make you final application of Aluminum Sulfate to the soil (assuming your plant has not already bloomed).  White flowered varieties will not be effected and not all pinks will be effected the same.

lawns, lawn, plant, seed, sod, ryegrass, bluegrass, springtime, garden

Lawns:

  • Apply your second and last application of pre-emergent Crabgrass Control to lawns to prevent the germination of crabgrass.
  • If needed, de-thatch and aerate lawns like hybrid bermudagrass and St. Augustine this month.
  • Remember, cool-season lawns should be mowed about a half an inch higher in the warm months than in the cool months.  This is a good month to raise the height.
  • It’s getting a bit late to attempt to plant new cool-season lawns from seed or sod (fescue/Marathon, ryegrass, bluegrass).
  • Continue feeding all lawns this month.  Cool-season grasses like fescue, ryegrass and bluegrass are still growing well.  Warm-season grasses like bermudagrass, St. Augustine and zoysia are also growing quickly in the warming temperatures.
  • This is also a great month to plant warm-season lawns (hybrid bermudagrass, St. Augustine, etc.) from sod. Most warm-season grasses do not grow from seed and are best only installed from sod.
  • Remember, cool-season lawns should be mowed about a half an inch lower in the cool months than in the warm months.  Keep the mower at this higher setting for the next several hot weather months.

cymbidium orchids, outdoor orchids, bloom, feeding, low nitrogren, flowers, cut back

Orchids (outside grown):

  • Cymbidiums are now done blooming and are entering their growing period.  Once they finish blooming, switch their fertilizer to one with a high nitrogen fertilizer that is preferably free of urea.
  • If pots of cymbidiums are excessively crowded and have a few leafless, brown bulbs showing (these are called “back bulbs”), it is time to divide and re-pot them.  Many beginners are intimidated by this important chore.  It is really quite simple.  Check a reference book or get a “how-to” sheet at a good nursery for the simple procedure.
  • You may need to move outdoor orchids to slightly more shade.  Now that the sun is higher in the sky and the days are longer be careful not to sunburn your plants.

ornamental grasses, new growth, salvia, fountain grass

Ornamental Grasses:

  • The grasses that were cut to the ground in the winter are looking great now.  Another application of a mild organic fertilizer will help them along.

perennials, bearded iris, bulbs, tubers, cannas, dahlias, fuchsias, geraniums, ornamental grasses, begonias, peony,

Perennials:

  • (See also Bearded IrisBulbs/Rhizomes/TubersCannasDahliasFuchsiasGeraniumsOrnamental Grasses and Tuberous Begonias)
  • This is still a good planting month for perennials.  The selection is good and many will be in bud or bloom.  Be sure to keep them well watered as these young plants head into the warm summer months.
  • Keep fertilizing your perennials.  The frequency and amount will depend upon the formulation that you are using.  If you have been building up your soil health your fertilizing duties will be much reduced.
  • Most of your perennial “chores” should have already been done and you can now enjoy your perennials in all their colorful glory.
  • Sub-tropical perennials have perked up now and should be putting on new growth and maybe even buds and flowers.  This is also a good month to plant these heat lovers.  These include begonias, heliotrope, impatiens, lamium, pentas (starflower) and plectranthus.
  • Keep tying the flowering spikes of tall, upright, spiking perennials, like dahlia, delphinium, foxglove, true lilies and monkshood (aconitum) to the bamboo stakes that you put in earlier in the year.
  • Removing the myriad of spent or old flowers regularly always helps them to produce more new flowers.  This is a good time to cut some fresh flowers for a vase as well.

pests, diseases, plant diseases, organic control, aphids, snails, slugs, beneficial insects, caterpillars

Pests & Diseases:

  • (See also the information under the individual plants and Beneficial Insects)
  • Gophers, rabbits and ground squirrels may start invading your garden this month.  As their hillsides, vacant lots and wild areas, which are reliant on natural rainfall dry up they begin moving into gardens for a steady supply of food to maintain them throughout the long dry summer months.
  • First month to worry about caterpillars.
  • Rose Slugs.
huntington library, places to visit, where to visit, gardens to visit, gardens, arboretum

Huntington Library

Places to Visit:

  • Gardens that look terrific almost any time of the year include Sherman Library and Gardens (Corona del Mar), The Fullerton Arboretum (Fullerton), Los Angeles Arboretum (Arcadia), Huntington Library and Botanical Gardens (San Marino) and Quail Botanical Gardens (Encinitas).
  • Rose Hills Memorial Park (Whittier).
  • The rose garden at the Huntington Library and Botanical Gardens, especially for David Austin varieties.
  • One of the finest Mediterranean gardens anywhere is the Leaning Pine Arboretum in San Luis Obispo, on the campus of Cal Poly Pomona.  Beautifully planned, immaculately maintained and horticulturally more innovative than any on the west coast, this garden should not be missed.  This is the perfect month.
  • This is a good time for a visit to our moist canyons and oak woodlands to observe our native plants.  Good choices might include Hot Springs Canyon, upper Trabuco Canyon and the area around Blue Jay Campground.
  • Richard Nixon Library and Birthplace, Yorba Linda.
  • Home garden tours.
  • The much anticipated Huntington Library and Botanic Gardens Annual Spring Plant Sales generally the on a Sunday during the middle of the month (it is open to members only the day prior).   Lots of new and hard-to-find plants are usually available at this event.  If you are a plant collector, arrive early.

planting, trees, shrubs, perennials, flowers, vegetables

Planting:

  • (See also the information under the individual plants)

poinsettias, holiday flowers, plant

Poinsettias:

  • Pinch the tips of the new growth (as long as it is at least 3-4 inches long) to encourage branching and more flowers.
  • Fertilize the plant often with a well balanced food to encourage growth.
  • Watch for whiteflies and treat as needed.

garden journal, records, catalogs, garden books, organizations

Records, Catalogs, Books and Organizations:

  • This is another great month to be making lots of entries into your garden journal.  Make notes now about what is blooming, what you like, what you don’t like, plant combinations and so on.  Especially important are the entries that you will make now that guide your garden activities this fall.
  • Continue making notes about your roses; which are performing well and which are not.  Notes on disease tolerance will be useful next winter if you decide to upgrade any plants.
  • This is another month of many home garden tours.  If you haven’t participated in one of these before you have missed one of the most rewarding gardening experiences.

roses, blooms, first bloom, healthy, flowers, granular, pests,

Roses:

  • In most gardens this will be the biggest rose bloom of the year.  The flowers will be huge and the colors rich.  The flowers will hold their form well in the May temperatures and the foliage is lush and healthy as well.  Enjoy the show.
  • If you love roses, this is a great month to get out and visit other great public roses gardens.  The biggest and best are at Roses Hills Memorial Park (Whittier) and the Richard Nixon Library (Yorba Linda).
  • Roses are heavy feeders; continue fertilizing them regularly.  Do not use soil-applied fertilizers that are combined with a systemic insecticide.  These products are very disruptive to soil life (beneficial microorganisms, bacteria, mycorrhizal fungi, earthworms, etc.).  Many rosarians also believe they reduce the vigor of the rose.
  • Granular, well-balanced, organic fertilizers work especially well for roses and most of these will encourage beneficial soil life.
  • Keep deadheading roses as they fade.  Cut them just above a leaf with five leaflets.  Floribunda’s, many English roses and some others are deadheaded on very short stems until the last of the flowers in the cluster have faded.  Then cut down to just above the first leaf with five leaflets.
  • Be on the lookout for pests.  Aphids will be less of an issue as the weather warms up now and can usually be hosed off with a strong jet of water.  Flower thrips may require an insecticide.
  • Keep on the lookout for diseases.  Powdery mildew and rust are the primary issues.  In warm inland gardens these are primarily springtime issues and in another month or so may disappear by themselves.  Regular grooming, early removal of infested leaves, good air circulation and full sun will help considerably.
  • If diseases do require a fungicide, use one of the newer, safer, organic products available.  These include Rose Defense (a neem oil extract), E-Rase (jojoba oil) or Saf-T-Side (straight paraffinic oil).
  • Potted roses are still in good supply and the selection is excellent now at the nursery.  It is a good time to add more or upgrade any that you are struggling with.
  • Keep making notes in your garden journal about which roses are performing well and which are not.  Notes on disease problems will be useful later if you decide to upgrade any to improved varieties.
  • One of the most obvious pests, especially in coastal gardens has now shown up.  Commonly called “Rose slug”, it is not a slug at all, but the larval form of a fly relative, called a Sawfly.  These little caterpillar-like pests are hard to spot, but chew on the undersides of foliage.  Eventually, irregular holes are eaten through the leaves.  Neem oil will work on them as will organic Pyrethrin sprays, but the applications must be thorough, frequent and applied to the undersides of the leaves.
  • Irrigations should be frequent now as the weather warms and the days lengthen.
  • For the biggest flowers pinch out some of the competing buds while they are very small.
  • Hose off the foliage of roses frequently.  Contrary to popular myth, this will actually reduce the likelihood of powdery mildew and keeps the foliage clean and healthy looking.
  • Weed as needed, but avoid most herbicides around roses.

shrubs, vines, large space, garden, garden design

Shrubs and Vines:

  • (See also the information under AzaleasCamelliasGardeniasHydrangeas and others)
  • In general, many shrubs will be growing quickly now and they may want to grow too large for their space.  They may even want to grow into small trees.  This may be what you want, but if not they will need clipping to restrain them.  Pruning these shrubs is best done just following their bloom cycle, which may be now.
  • Hedges are growing like mad.
  • If you haven’t already, this is about the last chance to prune winter and spring flowering vines that have finished their bloom cycle for this year.  These include Pink Jasmine (Jasminum polyanthemum), Hardenbergia species (Lilac Vine), Jessamine (Gelsimium species), Cat’s Claw (Macfadyena unguis-cati), Flame Vine (Pyrostegia venusta) and Wisteria (see separate entry).
  • Don’t prune summer blooming vines – those that haven’t flowered yet.

soil, soil care, foundation, healthy soil, organic mulch, mulch, mycorrhizae

Soil Care:

  • We have included this section, because as you know, or will discover with more experience, a good garden begins with the soil.  Investing in the soil, managing the soil and protecting the soil are not afterthoughts in a successful garden, but the foundation.  Healthy soil is living and breathing, teaming with earthworms, microorganisms, beneficial fungi, bacteria, microbes and other invisible life.  This section, possibly the most important topic of all will, provides some helpful guidance to good soil care.
  • A thick layer of organic mulch, averaging about two inches, should be maintained on top of the soil just about year-round.  Add additional mulch as needed to maintain this level.  Applied now, a thick layer of mulch will cool the root systems from hot summer temperatures, reduce irrigations as much as half this summer, reduce weed growth, and improve both soil life and soil quality.
  • If you have been considering inoculating your soil with beneficial mycorrhizae, this is  still a great month in which to do it.  The soil temperatures are right for quick establishment.  Inoculation can be done very quickly and easily in established areas by using mycorrhizae “tablets”.  In moist soil, poke a hole near the plant with a ½” or ¾” rod or stick.  Drop a tablet into the hole and push it in again with the stick.
  • We do not suggest the use of very high analysis fertilizers in a garden, especially phosphorus.  Examples of fertilizers to avoid are synthetic versions with formulations like, 10-55-10, 10-30-10, etc.  We don’t even suggest the popular 15-30-15 formula.  These formulations will inhibit or even destroy much of the soil life that is so vital to a healthy sustainable soil.
  • We also suggest that you not use soil-applied systemic fertilizer/insecticide combinations (especially popular with roses).  These are very damaging to soil life.
  • Use insecticides only when necessary and even then use the least damaging product available.  Many of these products move into the soil and interfere with the invisible soil life.
  • If you can, begin a compost pile or purchase a compost bin.  Leaves, clippings, kitchen produce scraps, and many other ingredients can be composted and returned to the garden.  Home compost is one of the very best ingredients you can add to your soil and the warm air temperatures of summer will help the composting process to happen quickly.  The benefits are huge in the areas of disease suppression, increasing beneficial microorganisms, improving soil structure and texture, nutrient retention and nematode suppression.
  • Be sure that before you put a plant into the ground you have considered the soil and are doing all you can to improve it and protect its health.

strawberries, feed, organic acid fertilizer, cottonseed meal, low pH, strawberry, fruit, kitchen garden

Strawberries:

  • Feed them regularly. Periodically alternate with an organic acid fertilizer. Like cottonseed meal, to keep the soil pH low, which strawberries prefer.
  • Bait, trap or hand pick snails and slugs regularly to avoid fruit damage.
  • Strawberry fruit will be less likely to be bothered by pests or rotting if separated from the soil slightly.  Use straw, pine needles or rings cut out of unprinted corrugated cardboard.

subtropical fruits, trees, flowers, harvest, kitchen garden

Subtropical Fruits:

  • (See also the information under Avocados, and Citrus)
  • Almost all of these are now awake and growing.
  • This is a good month to begin serious plantings of these heat lovers.
  • Fertilize with a general-purpose organic fertilizer.  Most tropicals and sub-tropicals have a higher need for trace minerals like iron, zinc, manganese and others.  Organic fertilizers generally contain lots of these trace minerals and work especially well in the warm soil temperatures present now.
  • Watering should be frequent now, but most tropicals and sub-tropicals are particular about quick soil drainage.

sweet peas, sweet pea, harbinger, full bloom, spring bloom, flowers, fragrance, garden flowers

Sweet Peas:

  • These should still be blooming wonderfully now, as long as you have been feeding and removing the dead flowers religiously.  This deadheading may be as often as twice a week.
  • Feed regularly.
  • Assist them with climbing and support if necessary.
  • They may be beginning to show a little heat stress, particularly at their bases where yellowing and drying will be noticeable.

trees, avocadoes, citrus, deciduous fruit trees, subtropical fruits

Trees:

  • (See also the information under AvocadosCitrusDeciduous Fruit Trees and Subtropical Fruits)
  • This is an acceptable month to prune tender sub-tropical trees like Ficus, Coral Tree, Avocado, Citrus, etc. (most other trees are best pruned in late fall or winter).  These sub-tropical trees should not be pruned during the cool winter months.  However, care must be taken not to disturb nesting birds at this season.  You may also interfere with flowering of certain species.

tropical, subtropical

Tropicals & Subtropicals:

  • (See also the information under AvocadosCitrus and Subtropical Fruits)
  • Almost all of these are now awake and growing.
  • This is a good month to begin serious plantings of these heat lovers.
  • Fertilize now with a general-purpose organic fertilizer.  Most tropicals and sub-tropicals have a higher need for trace minerals like iron, zinc, manganese and others.  Organic fertilizers generally contain lots of these trace minerals and work especially well in the warm soil temperatures present now.
  • The real heat-loving tropicals should be awake and growing well now.  These include Plumeria, Ginger, Ixora, Heliconia and others.
  • Watering should be frequent now, but most tropicals and sub-tropicals are particular about quick soil drainage.

tuberous begonias, tubers, growth, flowers

Tuberous Begonias:

  • Plants should be growing well and with a bit of luck there may already be some buds appearing.  Don’t worry too much about flowers though.  Right now you just want the plants to grow healthy and full.  In fact, some gardeners pinch out the first set or two of flowers to focus more energy on the growth of the plant.
  • Keep fertilizing regularly.  They are heavy feeders, especially in containers.  Use a well balanced fertilizer and periodically mix in an acid fertilizer, to keep the soil pH low.
  • Keep them well watered, but not soggy.  The soil should be rich and well-drained.  The surface of the soil should dry slightly between watering.
  • If powdery mildew appears treat it by improving air circulation around the plants.  Usually this will correct the problem, if not use a fungicide.

vegetables, artichokes, plant vegetables, vegetable garden, veggies, kitchen garden, harvest, raised bed gardening

Vegetables:

  • Almost any warm-season vegetable can be planted this month.  From transplants or seeds, plant beans, celery, cucumbers, eggplants, lima beans, okra, peppers, squash and tomatoes.  Corn, jicama, melons, pumpkin and sunflowers are best planted from seed.
  • Along the immediate coast gardeners can keep growing many of the cool season crops like arugula, lettuce, peas and members of the cabbage family.  However, real heat-loving vegetables like corn, melons, peppers and pumpkins will need a hot south facing wall.
  • This may be the best month of all for planting the real heat lovers like corn, eggplant, jicama, lima beans, melons, okra, peppers and pumpkins, now that the soil and night temperatures have warmed.
  • Plant giant forms of pumpkin toward the second half of this month for a Halloween harvest. Specifically, these are the huge varieties like ‘Big Max’ and ‘Atlantic Giant’. Standard types should be planted next month.
  • The first two or three weeks of flowers on squash and pumpkins are male flowers and will not set fruit.  Don’t worry when these dry up, everything is ok.  The female flowers will be along shortly.  Better yet, use these male flowers as a tasty garnish in the kitchen.
  • Putting in successive plantings of many vegetables a couple of weeks apart from each other will insure a constant, uninterrupted supply for the kitchen.
  • Keep tomato plants trained inside their cages or, alternatively, up sakes or obelisks.
  • Potato tubers, from those planted last fall, may still be ready for harvest.
  • Keep planting corn from seed this month.  Because corn needs to be cross-pollinated it must always be grown in clumps or rows.  Twelve plants is about the minimum for good pollination and twenty or more is even better.  Plant crops successively every three to four weeks for a continual harvest.
  • If planted in small groups, hand pollinate corn.
  • Beets, carrots, chard, radish and possibly turnips can be planted just about year-round.  All but chard are planted from seed only.
  • Since most annual vegetables are shallow rooted and quick growing, feed them regularly with a well balanced organic fertilizer and keep them well watered during warm weather.
  • Control weeds before they get out of hand.

Water, irrigation,

Water & Irrigation:

  • (See also the information under the individual plants)
  • Deep watering.
  • Automatic timers can be turned back on now.
  • Check sprinklers for adjustments, faulty heads, etc.
  • Continue adjusting the duration and interval settings of automatic sprinkler systems as the weather dictates.

wildflowers, bloom, superbloom, super bloom, reseed

Wildflowers:

  • Most of these will be over their bloom peak and beginning to look a little stressed.  You may be able to extend their season a bit with some additional irrigations.
  • If you want some of your wildflowers to re-seed for next year, leave them in place for a while and allow the seed to fall to the soil.
  • These should be about done and looking rather dry.  Irrigations may help a bit, but the end is near for these.
  • If you are trying to get some of these to re-seed for next year, don’t be in a hurry to pull them out.  Leave them in place until thoroughly dry and allow the seed to fall to the soil.

wisterias, bloom, pruning, wisteria, full bloom, purple

Wisterias:

  • This is the end of the main bloom period for wisterias.  If proper pruning was followed all year, the flower show should have been spectacular.
  • For established plants, wait until next month for the first in a three-pruning-per-year cycle.
  • On young plants, guide the long, twining stems carefully in the direction that you want.
  • A better looking plant will be the benefit if you prune off the dead flowers as they finish blooming.  This will prevent unattractive seedpods from developing on the plant.
  • If your wisteria has been planted for only a year or two, be sure to provide it with plenty of water and fertilizer it to encourage quick coverage and deep roots.
  • Established wisterias are better with only an occasional deep summer watering and little, if any, fertilizer other than possibly iron (to correct chlorosis).  Wisterias are large, aggressive vines; additional water and fertilizer will only create more rampant growth and more pruning needs.
  • Continue planting new wisterias now.  If possible, choose them while in bloom.  Grafted plants are preferred, since they will almost always bloom at a much younger age.
By | 2017-09-28T14:55:59+00:00 May 2nd, 2017|Gardening, Gardening Checklist|4 Comments

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4 Comments

  1. Mike Farrell May 5, 2013 at 4:03 pm - Reply

    Am I ok using Tomato Cages for my Dahlias…? Last year I tried just staking them and they were VERY unruly…

  2. Ron Vanderhoff May 6, 2013 at 7:53 pm - Reply

    Hi Mike.

    Actually, I know several people who use short tomato cages for their dahlias. They work perfectly. They actually surround the dahlia and prevent the stems from falling under their own weight.

    Ron

  3. Molly O'Callaghan May 26, 2017 at 11:20 am - Reply

    Hello! I am a first time gardener and new to California! I am trying to figure out how to keep my plants from wilting in this heat even though I water them twice a day (but not over watered). I also have something eating my cucumber, zucchini, and yellow pepper leaves. Are there any flowers I can plant or natural remedies to help this? I’m thinking my solution is to cover the plants with a light netting at night?

    Thanks in advance for the advice!

    -First time gardener

    • Roger's Gardens May 30, 2017 at 8:40 am - Reply

      Hi Molly,

      Welcome to Southern California, a gardening paradise. You will love it here.

      I am trying to understand why your plants are wilting, even if you are watering twice a day, which seems far more that you should need to. Something isn’t right here. Are these potted plants, recently planted plants, established plants or plants in the ground? Do be sure that when you water you are watering very thoroughly and wetting the entire root zone from top to bottom, not just wetting the surface.

      There is a saying in gardening that “you cannot water too much, you can only water too frequently”. Be sure you are applying plenty of water, quite deeply. Like the saying above, you can’t put too much on. Other than wasting water, applying too much is not going to cause problems, but applying too little is.

      Regarding pests, we are an organic retailer. We do not sell and suggest synthetic pesticides, fertilizers, weed sprays, etc. The remedy for different pests is likely going to vary with the pest, so I cannot give a simple answer. Snail and slug problems (which chew leaves) are handled completely differently than caterpillars (which also chew leaves), which are handled completely differently than grasshoppers (which chew leaves), which are handled differently that beetles (which chew leaves) and so on.

      We need to determine what the pest is before we can provide a solution. At some point in your gardening time you will probably need to use an organic pest control product. You might want to consider getting a ready-to-use container of natural and organic horticultural soap or pyrethrin and having it on standby. Again, it is best to know what you are trying to control before you start spraying, but these two products are in most organic gardeners arsenal.

      The netting may or may not be effective. If the pest is from moth larvae or from herbivores like rabbits or squirrels, it may be effective. But it will be of little use on other pests.

      I hope this helps. We will be here to help. Keep reading the month “What to do in your garden” installments, join us for our free weekend edible gardening seminars, check out our videos and read our blogs. You’ll do fine.

      Ron

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