May is the busiest month in my garden. Spring blooms give way to early summer blooms. Perennial bloom takes over for bulbs. The vegetable garden gets planted, fruit trees get attention and, if I’m lucky, the earliest stone fruits are ready to pick by month’s end. May is a glorious time to garden!
Vegetable gardens
Are you new to vegetable gardening? Or have you had trouble starting summer vegetable, herb and flower seeds in the past? Enroll in my Easy Seed Starting Online Course to learn the best, easiest and most successful way to start seeds. Sign up at bit.ly/seedstarting2024.
As soon as night temperatures stay reliably above 50 degrees, it’s safe to plant out summer vegetable seedlings.
What to plant now:– From seed: cucumber, squash (winter and summer), pumpkins, melon, carrots, radishes, beans, cilantro.– From seedling or start seeds in containers to plant out in six weeks: tomato, okra, basil, marigolds, eggplant, tomatillo, peppers.
If you shop for seedlings, buy the smallest seedlings you can find. Skip large seedlings and don’t ever buy large plants, especially those with fruits or flowers. Those plants are too old already. Younger plants will establish better, grow into larger, healthier, more vigorous plants that produce far more.
Since our native soils have very little organic matter, plan to grow vegetables in raised beds — either free standing or on the ground. If you don’t have room for raised beds, use half whiskey barrels, EarthBox or similar planters with a large volume of growing medium.
Building and planting your first on-the-ground raised beds? Here’s how: tinyurl.com/buildraisedbeds and tinyurl.com/plantraisedbeds.
Fill on-the-ground raised beds with a topsoil mix — not with potting soil, not with planting mix, nor with any of the bagged raised-bed mixes. Use a topsoil that is at least 40 percent organic matter (compost). Add in a generous dose of worm castings and organic granular vegetable fertilizer. Mix in to the top few inches using a hand trowel; do not rototill.
Fill pots, freestanding raised beds and whiskey barrels with good-quality potting mix. Do not use planting mix or “dirt,” and don’t cheap out on the potting mix. Your plants only grow as well as the quality of the mix they are planted in.
Whatever your growing situation, fill the pot, bed or planter with the same material from top to bottom. Don’t be tempted to fill up space with logs, branches, leaves, plastic bottles, gravel or anything else. Layers like those create a “perch” layer that prevents soil from draining. Your plants can literally drown. It’s simply a matter of physics.
Revitalize last year’s raised beds and planting containers by topping them off with compost, worm castings and organic vegetable fertilizer. Mix in to the top few inches using a hand trowel; do not rototill.
Irrigate raised beds with Netafim Techline EZ inline dripline, with emitters spaced six inches apart. Before you plant, lay out the irrigation in a grid of straight lines, set six to eight inches apart.
GIVE PLANTS SPACE. Seedlings grow into much larger plants than you expect. Overcrowded plants never reach mature size. Instead, they form a giant, jumbled jungle — the perfect condition for killer molds, mildew and other problems, too. Here’s what to expect:– Tomato: 3 to 6 feet wide and 6 feet tall.– Pepper and eggplant: 2 to 3 feet wide and tall.– Pumpkin and melon: vines up to 30 feet long in every direction.– Zucchini: 3 feet across.
– Tomatillo: 3 to 4 feet tall and wide.
– Basil: 2 feet tall and wide.
Planting into containers?– A 15-gallon nursery can or a half whiskey barrel accommodates one tomato plant, or two eggplants, or three basil plants, or four cucumber plants, or two pepper plants.– A 5-gallon nursery can is big enough for two eggplants, two basil plants, or two pepper plants.– A 5-gallon bucket with holes drilled in the bottom can support one tomato or two eggplants or three basil, or two pepper plants.
Rotate tomato, pepper, eggplant, tomatillo and potato plants to a different garden bed. These plants cousins are all vulnerable to the same “bad” soil viruses, fungi, bacteria, etc. Alternate them with annual herbs, root vegetables, flowers, okra, beans or other plants that are not in the tomato family. Swap locations each year.
To prune or not to prune tomato plants? Experts say there’s no reason to prune and many reasons not to. Contrary to legend, pruning does not increase production (why would it? Leaves power the plant, so when you remove leaves, you limit fruiting power). Overpruning leaves fruits exposed to sunscald. It is, however, smart to remove selective branches for good airflow and avoid mildew. Use your fingers to break off the branches, then wash your hands between plants so you don’t spread diseases from one to the next.
Fruit trees
Stone fruits, apples, pears, figs, pomegranates, pineapple guava, persimmon and many other summer and early fall fruits are developing now.
Thin out any marble-size apples, pears and stone fruits to just ONE fruit every five or six inches along the branch. Too many fruits make for tiny fruits and broken branches.
Water stone fruits, apples and pears deeply and regularly through the growing season. Remember to fertilize them with organic, granular, all-purpose fruit tree fertilizer. Follow label directions.
Water figs, pomegranate and pineapple guava only once every few weeks — deeply each time. Mulch them but don’t fertilize.
Peach leaf curl is disfiguring leaves on lots of stone fruits this year, even those sprayed well with fungicide and horticultural oil last winter. It is caused by a fungus that thrives in humidity (another reason to stop using overhead spray irrigation). There’s no treatment for it now and no reason to remove the disfigured leaves since they still photosynthesize to make energy and power fruit development. Plan to spray next winter.
Pick fruits as they ripen and before critters get them. Pick up fallen fruits and set traps for rats.
Continue watering and fertilizing citrus and avocado. Water under the entire canopy to wet surface roots, and water a long time to wet deep roots.
Disfigured citrus leaves are likely citrus leaf miner. Do NOT cut off the leaves. They are ugly, but don’t affect fruiting. Cutting off those leaves makes things worse. Why? Pruning stimulates new growth, and those new leaves are leaf miners’ favorite, so the problem will only get worse.
Bananas and other subtropical fruits are the thirstiest fruiting plants. Water once a week or more, deeply each time. Fertilize regularly and mulch thickly to keep moisture in the soil.
Don’t make the mistake of planting citrus trees (or any other tree) into lawn. Their water and fertilizer needs are very different and lead to crop failure. Instead, plant citrus and avocado into beds with a dedicated inline drip irrigation zone. Mulch.
Ornamental plants
Nurseries feature plants when they look prettiest, but that’s not the time to plant them. Take a walk through your neighborhood and make note of what’s blooming now. Add those plants to your garden in fall, and choose the small plants, not yet in bloom.
Plant annual flowers in or near your vegetable garden: marigolds, calendula, zinnias, sunflowers and more. They support pollinators and beneficial insects.– Tube-shaped flowers support hummingbirds, butterflies and moths: sages, Grevillea, native currants (Ribes)– Large clusters of small flowers support butterflies and moths: Aster, mints, milkweed– Flat, wide flowers support bees: poppies, native Clarkia, Zinnia, Aster, daisies– Bowl-shaped flowers and flat flowers support beetles: California poppies, magnolia, sunflowers, yarrow
Did you know: Beetles pollinate 88 percent of all flower plants around the world!
Inland, stop planting drought tolerant shrubs and trees, including natives, now. The heat will set in before those plants are through transplant shock. Continue planting in coastal gardens.
Deadhead roses and spring perennials to encourage more blooms. Always cut at a branching point. Never leave a stub.
Have you discovered Mangave? These Agave/Manfreda crosses grow as beautiful succulent rosettes with a great variety of spots and stripes in shades of blue, brown, yellow, red, green and silver. They are easy to grow and add a punch to the garden. Look for varieties like ‘Snow Lion’, ‘Mission to Mars’, ‘Black Magic’, ‘Dreadlocks’, ‘Chocolate Chip’ and others.
This is the time to replace your lawn with a “meadow” of natives like clustered field sedge (Carex praegracilis), native bent grass (Agrostis pallens), and blue grama grass (Bouteloua gracilis). Check your local water district for turf rebate programs before you remove the lawn.
Pests
Plants grow many leaves — a few holes in plant leaves aren’t a problem. Just ignore them.
Spray whiteflies and aphids off with a sharp stream of water using a Bug Blaster hose end nozzle. The critters’ soft bodies can’t withstand the impact of the spray. Repeat every few days for several weeks to interrupt their reproductive cycle.
Eliminate ants to control aphids, mealy bugs and scale. Ants “farm” these bugs by moving them around the garden and harvesting the sweet “honeydew” they excrete. It is the perfect ant food.
Got gophers? Protect new plants by planting into gopher baskets. Line the undersides of raised beds with hardware cloth. Catch tunneling gophers with GopherHawk traps.
Fungus gnats in houseplants are pesky but don’t damage plants. Give your plants an outdoor vacay now that it’s warm at night. Native predators will take care of the gnats for you.
Got slugs? Slugs and snails abound after the wet winter. Sprinkle Sluggo into garden beds to kill them. Check plants at night for tell-tale slime trails.
Manage water
Despite the abundance of winter rain, by summer it will be dry again. Stick to your water-conserving ways.
Startup your irrigation system now that rains have ended. Water only when the soil is dry, once every week or two or three.
Cover the soil with a 3- or 4-inch-thick layer of mulch, leaving a bare sunny spot for ground-dwelling native bees. These bees are important pollinators in gardens and for native plants; they rarely sting.
Use rock mulch for succulents, wood-based mulch for nonsucculent ornamental plants, straw (not hay) on vegetable gardens.
The goal of irrigating is to wet roots, so water long enough to get water down to the root zone — with drip irrigation that could take an hour or two. Stick your fingers down into the soil to be sure it is wet as deep as the roots go. Wait to water again until the soil dries out.
Run irrigation before 6 a.m., before peak weekday water demands. Drip can run at night, but not overhead spray. Wet leaves in the cool hours are susceptible to molds and mildew.
Sterman is a garden designer, teacher, author and the host of “A Growing Passion” on public television. She runs Nan Sterman’s Garden School at waterwisegardener.com.