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April Gardening Tips for Los Angeles County Residents
by Yvonne Savio
-- This month's discussion of garden tasks is based on my 60 years of gardening at my home in Pasadena.
-- For my comments on current weather conditions and activities, see my blog page which includes archived blogs since 2015.
-- For my discussions of major gardening topics, see my homepage listing.
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Most gardeners have been out in the garden for several weeks already, but anytime this month is a great time to start incorporating soil amendments, sowing seeds, and putting in transplants. The soil is dry enough to be worked without compacting it, the air is warm enough to enjoy working outside, and the soil temperature is ideal for germinating all kinds of seeds and getting transplants growing well. In short, it's garden time!
Vegetables and Fruits
Sow or transplant asparagus, beets, carrots, celery, chard, herbs, kale, kohlrabi, leeks, lettuces, okra, summer-maturing onions, parsley, peanuts, the last peas (choose a heat-tolerant variety such as Wando), white potatoes, radishes, rhubarb, and spinach.
Transplant early-maturing varieties of beans, cucumbers, eggplants, melons, peppers, squash, and tomatoes that will tolerate cooler soil temperatures. For protection from pests and some nightime chill, cover them with hotcaps or clear plastic water jugs with their bottoms and caps off. Continue reseeding a flat of heat-tolerant leaf lettuce throughout the summer to have seedlings to plant into unused spots as earlier crops are harvested. Herbs to sow or transplant include anise, basil, borage, burnet, catnip, chervil, chives, cilantro (when it's seed, it's called coriander), comfrey, dill, fennel, lavender, marjoram, mint, oregano, rosemary, sage, savory, tarragon, and thyme. Many perennial herbs make attractive, drought-tolerant, trouble-free landscaping plants. Herbs that also produce indoors are dwarf green or dark opal basil, chervil, chives, dill, marjoram, oregano, parsley, savory, and thyme--as long as they get lots of direct sun and fresh air. Wait until the end of the month to sow or transplant vegetables and fruits that prefer very warm weather to mature--including beans, corn, cucumbers, eggplants, melons, peppers, pumpkins, and squash. They will do better when they have consistently warm soil and air temperatures. Planting them into the soil when air temperatures are still cool results in growth stress which is difficult for the plants to overcome. Peppers, especially, will just "sulk" if their roots are chilled, and they won't recouperate quickly--so, it's best to just wait till the soil has warmed before planting them, and they'll outthrive the earlier-planted ones. Add to your garden some edible flowers for their foliage and their bloom. You may already grow some--the edible portion of artichoke, broccoli, and cauliflower are all immature flowers. Nasturtium leaves and flowers taste peppery. Squash blossoms have a cucumbery flavor. Some marigolds taste unpleasantly strong, but others are mild. Be sure, however, to harvest only flowers and foliage that haven't been sprayed with a pesticide not registered for food. Poor germination of seeds may result from several conditions. The seeds may be too old, poorly stored, or planted too deeply. The soil temperature may be too low or too high. The soil moisture may be too dry or too wet. The soil may have too much fresh manure, which burns the seedlings but is wonderful after it's aged a month or so later for transplants. Soil that forms a crust kills germinating seeds before they can break through the soil surface. To lessen this problem, cover the seeds with a thin layer of compost, potting soil, grass clippings, potting mix or other light-textured substances--rather than the heavier soil. Keep the area moist but not soggy until two "true" leaves develop. "True" leaves are the ones that look like tiny versions of the mature leaves. Sprinkling the bed with a fine spray of water several times a day also helps to keep it from crusting. If a muddy slurry results from irrigation, it will dry into a crust. If hornworms have plagued your tomatoes in the past, consider planting cherry tomatoes. Their thicker skins and higher alkaloid content seem to repel the worm. Adult hornworms are the larval form of large fast-flying, mottled gray or brown moths that will hover near tubular flowers at dusk later this summer. As you work your soil prior to planting, destroy the pupae--the hard, brown, two-inch spindle-shaped cases with a handle that are buried three to four inches underground. Feed vegetables with manure tea or fish emulsion when they are transplanted and every six weeks throughout the season for gradual and gentle feeding. Make manure tea by placing a container in the sun and filling it with one part manure and two parts water. Stir the mixture once a week. Within a month, a rich fertilizer tea will be ready to feed plants. Replenishing the container with manure and water after each use will maintain a ready supply throughout the season. Onion bulbs tend to split if the soil is alternately wet and dry early in the season during bulb formation, or if excessive nitrogen is applied during the two months before harvest. The weather from now through June is ideal for planting citrus, avocados, and other tender trees such as kiwis, kumquats, and pomegranates. In frost-free areas, also try cherimoya, guava, mango, and passion fruit. For growing in containers, be sure to choose dwarf varieties. For the best choice in citrus, look for trees with many strong branches, a smooth graft union, and deep green leaves. Prune frost-damaged wood once the plant or tree has completely leafed out and you can easily see exactly which wood is truly dead. If you're in doubt, wait another month to avoid pruning wood which was just late in leafing out. By mid-summer, any remaining deadwood will be obvious. Feed all trees heavily for strong growth and good fruit production. Topdress them with compost and fertilizers high in nitrogen (fish emulsion, chicken manure, cottonseed meal, blood meal), and phosphorus (bone meal and rock phosphate). Keep composts, manures, and fertilizers at least a foot away from tree trunks. Start thinning excess fruit set on trees and vines for better-developed remaining fruit and grapes with less strain on the tree or vine. This is especially important for those trees bearing fruit for the first or second time. Allow a spacing of five inches between peaches on opposite sides of the branch, and three inches between plums and apricots. Thin peaches before the fruit reaches almond-size for the greatest benefit in size and flavor of the remaining fruit. Be ruthless in your thinning: the fruits are small now but will take lots of energy to mature, and you don't want to stress the tree or vine to produce fruit you won't eat because there's too much ripening at one time. Paint tree trunks with light-colored indoor latex paint to prevent sunburn damage. Use an inexpensive brand, or thin down an expensive one to a solution of half water and half paint. This is the one time when "cheap" is best. Be sure to use water-based interior latex paint, because oil-based exterior oil paint will clog tree trunk pores, killing the tree. 
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Ornamentals
Sow or transplant all summer annual and perennial flowers. These include agapanthus, ageratums, alyssum, globe amaranth, amaryllis, asters, baby's breath, bachelor's buttons, balsam, beebalm, fibrous begonia, bougainvilleas, calendulas, campanula (canterbury bells), candytuft, carnations, celosia (cockscomb), chrysanthemums, cineraria, coleus, columbine, coreopsis, coralbells, cosmos, English and gloriosa and marguerite and Shasta daisies, daylily, delphinium, dianthus (sweet William, pinks), dusty miller, felicia, forget-me-nots, four o'clocks, foxglove, fuchsias, gaillardias, gazania, geum, geraniums, godetia, heliotropes, hibiscus, hollyhocks, impatiens, johnny-jump-ups, lantanas, larkspur, lavender, linaria, lobelia, lunaria (honesty, money, or silver dollar plant), marigolds, mimulus, morning glories, nasturtiums, nemesias, nicotianas, pansies, penstemons, periwinkle, petunias, phlox, California and Iceland and Oriental and Shirley poppies, portulaca (moss or sun rose), potentilla, primroses, pyrethrums (painted daisy), salvias, scabiosas (pincushion), schizanthus, snapdragons, statice, stock, strawflowers, sunflowers, sweet peas, tithonia (Mexican sunflower), torenia, verbena, violas, and zinnias.
Plant summer-blooming bulbs, corms, and tubers, including acidanthera, agapanthus, tuberous begonias, caladiums, calla lilies, canna lilies, dahlias, daylilies, gladiolus, iris, ixia, lilies, montbretias, tigridias, tuberoses, and watsonias. Place a tablespoon of a balanced fertilizer such as 10-10-10 a full inch beneath each bulb to keep the bulb developing for future bloom. Divide and transplant clumps of ornamental grasses. Continue watering and feeding a balanced fertilizer to spring-flowering bulbs until their foliage starts to yellow. This will strengthen the bulbs for further growth and next year's bloom. Then, let the bulbs thoroughly dry out. Dig and gently clean soil clods from them (but don't wash them), and store. Bulbs may be left in the soil only where it will thoroughly dry out over the summer and be chilled the next winter. Plant or prune ground covers to clear dead portions and stimulate new growth--including iceplant, ivy, potentilla, and wild strawberry. Drought-tolerant choices include coyote bush, creeping coprosma, gazania, Mexican evening primrose, rosemary, and verbena. Water-conserving blooming shrubs for dry spots include crape myrtle, oleander, rosemary, and wild or California lilac. For bushier plants with more blooms, pinch new growth of begonias, chrysanthemums, marguerite daisy, dianthus, fuchsias, geraniums, Swedish ivy, wandering jews, iceplants, lavender, pepperomias, philodendrons, pilea, and sedums. Root these cuttings for new plants. Pinch bloomed-out branches throughout the summer to keep plants looking neat, and to encourage their putting out new flower buds. Sheer formal hedges and prune evergreens--arborvitae, hemlock, juniper, pine, spruce--to control their size and improve their shape. Sow or lay sod for dichondra or grass lawns. Reseed worn patches of lawn. Cultivate the top four inches of soil well first with organic matter and slow-release fertilizers, so your lawn will thrive. Mow lawns up to two times a week to keep the height at about two inches. Don't remove more than one third of the green leaf blades at a time, or the individual grass plants won't have enough left to continue growing, or they'll get sunburned. Lawns are the greatest users of outdoor irrigation. It's important to make sure that the roots are growing deeply, and that they are getting the amount of moisture they need. The two-inch mowing height will allow the lawn to retain some surface moisture, so you don't have to water as often. To test how deeply your irrigation water is going, water for the usual length of time and then push a trowel into the soil its full length. Push the soil clump to one side, or lift it out completely, and look at both the depth of the roots and the water line in the soil--it'll be dark toward the lawn surface and lighter where it's dry. The water line should be just past the longest roots. If it's not this far down, replace the clump, water again, and test another spot until the water line is below the roots. Adding all these irrigation times together gives you the correct amount of time for each watering. Don't water again until two-thirds of the root length is again dry. This may mean that you can double the time between waterings, and the grass roots will not suffer during the really hot portion of the summer. Feed roses heavily to ready them for their long blooming season. Incorporate manure, bonemeal, and cottonseed meal within the plant dripline to the depth of three inches. Water deeply. Weekly or every other week until fall, prune the spent blooms down to the first five-part leaf or a bit further to gently shape the plant, feed lightly, and water. Repeating this process through the season will encourage continuous bloom throughout the season. Water only in the mornings or early afternoons to lessen mildew and other disease problems. Move sun-shy houseplant ferns from windows facing east and west to north-facing ones. Excellent all-year locations are south- or west-facing windows that have sun-screen film and an outside awning to protect the fern from direct sun. When ferns are potted in a porous mix containing some horticultural charcoal, you can water less frequently. Providing ferns with a deep drip dish that always has at least one-quarter inch of water in it will allow the fern to absorb as much as it needs when it needs it, without rotting. The deeper the drip dish is filled, the fewer times you'll have to refill it. For a general watering solution, use a quarter-strength fertilizer rather than a once-a-month, full-strength feeding and plain water at other times. This makes nutrients available as the fern requires them, resulting in a healthier plant. Misting the fronds of a fern may or may not be needed, depending on the humidity levels under which it was grown before you purchased it and now in your home. The fern can be "weaned" from its need for misting by lessening the frequency gradually over a two-month period, as long as sufficient water is available in the drip dish. A wide-bottom drip pan will provide humidity through evaporation up into the fronds. Container gardens can begin with just about any container--an old wheelbarrow, bathtub, bird cage, "distinguished-looking" shoe, child's wagon, or even just a camouflaged bag of potting mix. If it'll hold soil and a plant, it's fair game. Mounds or cascades of color can come from begonias, petunias, ivy, geraniums, campanula, impatiens, succulents, fuchsias, azaleas, or vegetables--patio or cherry tomatoes, strawberries, or herbs. |
General
Teaching plant roots to grow deeply for water while temperatures are still coolish will lessen their irrigation needs during hot weather. Make sure that irrigation drip lines, soaker hoses, sprinklers, and trenches are in place before root systems get too large.
The weather and the texture of your soil will determine the amount and frequency of irrigation to apply to your garden. Heavy clay soils require less irrigation than sandy loam soils. During periods of long, hot weather, plants need more frequent and longer irrigation than during periods with more moderate temperatures. Irrigation which keeps the soil soggy will increase root rot problems.
Mulch the soil--especially with organic matter such as leaves or grass clippings--to temper the drying and heating effect of the sun, and irrigation will be more effective with less frequency and quantity.
Continue pulling weeds before they form seedheads or scatter their seeds, and you'll have fewer weed problems later. Weeding the day after watering will ease the chore, and weeds' entire root systems will come out more readily. If you leave pulled weeds in garden pathways as dry mulch, be sure to leave them with their roots up so they don't reroot themselves. But don't leave weeds that have already developed their seedheads--some seeds may mature and germinate next year.
If you are considering constructing a compost pile but are leary of a potentially disagreeable smell and hovering insects, be aware that these result from the pile not being aerated enough. The foul odor and large numbers of insects are due to anaerobic decomposition.
To properly construct a "breathing" compost pile, collect some moist greenery such as grass clippings, green foliage, and kitchen scraps with no grease or fat; some dried leaves or woody material in small pieces; and some soil, manure, or compost.
Begin the pile on top of some rougher, dry brush or small twigs. Then mix the ingredients well or thinly layer them until the pile is about three feet tall and wide. Add finely-chopped, moist greenery such as grass clippings in thin layers, or stir them into the top layer of other ingredients. Otherwise, thick layers will compact, decompose, and smell rotten in the summer heat.
Water the pile until it's moist but not soggy. Mix the pile every several weeks to let in more air if it seems to be compacting without breaking down the ingredients.
Bonemeal promotes excellent root growth. It becomes available to your plants more quickly when it is mixed with manure or compost and dug into well-aerated soil.
Make your own complete, slow-release, and fairly well-balanced granulated fertilizer from natural ingredients. Use four parts seedmeal or fish meal; one part agricultural or dolomite lime; one part rock phosphate or one-half part bonemeal; and one-half part kelpmeal. Seedmeal is any kind of ground-up seed. Cottonseed is the most inexpensive and is easy to work with but contains the most pesticide residues. Fishmeal tends to be odorous for a day or two after incorporation (just think you're at the beach....). All are high in nitrogen and contain moderate amounts of phosphorus but little potassium.
Agricultural lime or the more balanced dolomite lime should be finely ground so they act quickly. Don't use quick lime or slaked lime. Bonemeal and rock phosphate are effective phosphate fertilizers. Bonemeal is faster-acting but is more expensive and tends to become lumpy. Kelpmeal adds potassium and many necessary trace elements.
To encourage beneficial insects to populate your garden, provide them with their chosen foods and habitats. Many weeds--including lamb's-quarters, nettle, knotweed, pigweed, and cocklebur--as well as many cultivated annuals, perennials, and herbs are food sources for two of the most important orders of beneficial insects, wasps and flies. Most of these plants are members of two families, the umbelliferae and the compositae. Umbelliferae--such as anise, carrot, caraway, coriander, dill, fennel and parsley--have many tiny flowers arranged in tight umbels. Compositae--such as black-eyed Susan, goldenrod, and strawflower--have central disc flowers surrounded by many ray petals.
Mustard flowers attract lacewings (for aphids) and parasitic wasps (for cabbage caterpillars and coddling moths; they don't bother people or pets). Multiples plants interplanted throughout the garden can support a large beneficial insect population.
Plastic gallon jugs with their bottoms cut out and caps removed can be used at least two times each year. When starting seeds or setting out plants when nights are still cool, use the jugs as hot caps. When the plants have outgrown the jugs or night time temperatures stay above 50 degrees, invert the jugs and bury their necks into the soil for use as funnels for irrigation and liquid fertilization that release the moisture deeply into the soil right at the rootzone.
Recycle 2-liter plastic soda bottles into drip-irrigation containers. Punch two small holes into the screw-on cap. Remove the hard plastic base, cut off the rounded bottom of the bottle, and replace the base as a cap. Sink the bottle upside down into the soil, and firm it around the bottle to hold it in place. Remove the base (now the top) to fill the bottle with water or fertilizer solution, and replace it to retard evaporation.
Gallon- or larger-sized containers with holes punched in the lower halves and bottoms can be sunk into the soil between plants or seedlings as watering tools. Irrigation and fertilizer solutions can be poured into these containers to gently seep into the soil. Plant roots will grow deeply in search of this nutrition and moisture, and these deep roots will support the plant well during longer periods of hot weather that will kill plants with more shallow root systems. The five-gallon and larger sizes can be used in the holes dug for hills of melons, squash, etc.--the container prevents the hole from filling up with soil with each watering.
The weather and the texture of your soil will determine the amount and frequency of irrigation to apply to your garden. Heavy clay soils require less irrigation than sandy loam soils. During periods of long, hot weather, plants need more frequent and longer irrigation than during periods with more moderate temperatures. Irrigation which keeps the soil soggy will increase root rot problems.
Mulch the soil--especially with organic matter such as leaves or grass clippings--to temper the drying and heating effect of the sun, and irrigation will be more effective with less frequency and quantity.
Continue pulling weeds before they form seedheads or scatter their seeds, and you'll have fewer weed problems later. Weeding the day after watering will ease the chore, and weeds' entire root systems will come out more readily. If you leave pulled weeds in garden pathways as dry mulch, be sure to leave them with their roots up so they don't reroot themselves. But don't leave weeds that have already developed their seedheads--some seeds may mature and germinate next year.
If you are considering constructing a compost pile but are leary of a potentially disagreeable smell and hovering insects, be aware that these result from the pile not being aerated enough. The foul odor and large numbers of insects are due to anaerobic decomposition.
To properly construct a "breathing" compost pile, collect some moist greenery such as grass clippings, green foliage, and kitchen scraps with no grease or fat; some dried leaves or woody material in small pieces; and some soil, manure, or compost.
Begin the pile on top of some rougher, dry brush or small twigs. Then mix the ingredients well or thinly layer them until the pile is about three feet tall and wide. Add finely-chopped, moist greenery such as grass clippings in thin layers, or stir them into the top layer of other ingredients. Otherwise, thick layers will compact, decompose, and smell rotten in the summer heat.
Water the pile until it's moist but not soggy. Mix the pile every several weeks to let in more air if it seems to be compacting without breaking down the ingredients.
Bonemeal promotes excellent root growth. It becomes available to your plants more quickly when it is mixed with manure or compost and dug into well-aerated soil.
Make your own complete, slow-release, and fairly well-balanced granulated fertilizer from natural ingredients. Use four parts seedmeal or fish meal; one part agricultural or dolomite lime; one part rock phosphate or one-half part bonemeal; and one-half part kelpmeal. Seedmeal is any kind of ground-up seed. Cottonseed is the most inexpensive and is easy to work with but contains the most pesticide residues. Fishmeal tends to be odorous for a day or two after incorporation (just think you're at the beach....). All are high in nitrogen and contain moderate amounts of phosphorus but little potassium.
Agricultural lime or the more balanced dolomite lime should be finely ground so they act quickly. Don't use quick lime or slaked lime. Bonemeal and rock phosphate are effective phosphate fertilizers. Bonemeal is faster-acting but is more expensive and tends to become lumpy. Kelpmeal adds potassium and many necessary trace elements.
To encourage beneficial insects to populate your garden, provide them with their chosen foods and habitats. Many weeds--including lamb's-quarters, nettle, knotweed, pigweed, and cocklebur--as well as many cultivated annuals, perennials, and herbs are food sources for two of the most important orders of beneficial insects, wasps and flies. Most of these plants are members of two families, the umbelliferae and the compositae. Umbelliferae--such as anise, carrot, caraway, coriander, dill, fennel and parsley--have many tiny flowers arranged in tight umbels. Compositae--such as black-eyed Susan, goldenrod, and strawflower--have central disc flowers surrounded by many ray petals.
Mustard flowers attract lacewings (for aphids) and parasitic wasps (for cabbage caterpillars and coddling moths; they don't bother people or pets). Multiples plants interplanted throughout the garden can support a large beneficial insect population.
Plastic gallon jugs with their bottoms cut out and caps removed can be used at least two times each year. When starting seeds or setting out plants when nights are still cool, use the jugs as hot caps. When the plants have outgrown the jugs or night time temperatures stay above 50 degrees, invert the jugs and bury their necks into the soil for use as funnels for irrigation and liquid fertilization that release the moisture deeply into the soil right at the rootzone.
Recycle 2-liter plastic soda bottles into drip-irrigation containers. Punch two small holes into the screw-on cap. Remove the hard plastic base, cut off the rounded bottom of the bottle, and replace the base as a cap. Sink the bottle upside down into the soil, and firm it around the bottle to hold it in place. Remove the base (now the top) to fill the bottle with water or fertilizer solution, and replace it to retard evaporation.
Gallon- or larger-sized containers with holes punched in the lower halves and bottoms can be sunk into the soil between plants or seedlings as watering tools. Irrigation and fertilizer solutions can be poured into these containers to gently seep into the soil. Plant roots will grow deeply in search of this nutrition and moisture, and these deep roots will support the plant well during longer periods of hot weather that will kill plants with more shallow root systems. The five-gallon and larger sizes can be used in the holes dug for hills of melons, squash, etc.--the container prevents the hole from filling up with soil with each watering.