For The Union-Tribune
March finally brought us some good rains, but rainfall was still barely half the normal amount. Chances of getting to normal, even if there are sprinkles in April, are pretty slim.
With less water banked in the soil and accessible to plant roots, chances are, we are looking at irrigating more into spring and even summer this year.
Attend
• April brings succulent experts and lovers from around the world to San Diego for the Cactus and Succulent Society of America’s biennial convention, April 23 to 27 at the Mission Valley Marriott. This world-class event includes talks, garden and nursery tours, a fantastic plant sale and much more. For more information and to register, visit cactusandsucculentsociety.org/events/convention.
• April 24 to 28 brings landscape designers and those interested in landscape design to the annual Association of Professional Landscape Designers International Landscape Conference at the Catamaran Resort Hotel and Spa. Enjoy speakers (including me) and nursery/garden tours, all focused on the theme of biodiversity, highlighting the vast flora of our region, as well as design practices that respect the local climate and ecosystems and support local wildlife. For more information and to register, visit apld.org/international-landscape-design-conference.
• On April 15 at 7 p.m., learn all about bees in my Third Thursday Zoom webinar, “Bee Happy,” with guest expert Hilary Kearny, author of “QueenSpotting,” “Heart of the Hive,” and “The Little Book of Bees.” Hilary is a bee educator, beekeeper and owns Girl Next Door Honey. Reserve your spot at bit.ly/beehappyHilary.
• Now through August, participate in my Easy Seed Starting Online Course to learn to start seeds and grow summer vegetables, summer flowers and annual herbs like basil and cilantro. Starting from seeds is most rewarding and gives you the most control over what you grow and what you eat. We grow together all season long! Sign up at nanstermangardenschool.com/easy-seed-starting-2025.
Take a tour
Garden tours continue this month. Find a listing of local tours at sandiegouniontribune.com/spring-tours.
Ceanothus bloom started in mid-March and keeps on going. Take a hike and look for the bright white blooms of hoaryleaf ceanothus (Ceanothus crassifolius) and white coast ceanothus (Ceanothus verrucosus), which is native only in San Diego and Baja. If you see blue blooming ceanothus, chances are it’s woollyleaf Ceanothus (Ceanothus tomentosus) or blueblossom ceanothus (Ceanothus thyrsiflorus). All of these beautiful natives are available in nurseries, but it’s too late to plant them for this spring. Make a note and add them to your garden in the cool of fall.
Wherever you go, stay on the trail. While photos of you standing (or sitting) in a field of wildflowers make great social media, your walking into the field crushes flowers and kills the plants you adore. Instead, stay on the road or on the trail. Frame your shot to show the flowers in the background.
Don’t pick the flowers and don’t dig the plants. Those plants’ and flowers’ seeds make next year’s plants and flowers. If you pick them, the plants and flowers go away. Plus, wild plants don’t transplant well, and wildflowers are very short-lived as cut flowers. Plant seedlings from the nursery instead. Cut their flowers for your bouquets.
Tour your own garden. Appreciate the beauty you’ve created. Take photos, make notes, enjoy. Share your images with other home gardeners in the San Diego Gardener Facebook group, facebook.com/groups/SDGardener.
Vegetable garden
April is the ideal time to start your summer vegetable garden from seed or from seedlings.
Wait to plant summer vegetable seedlings outside until overnight temperatures are consistently 50 degrees or higher. If you start seeds in containers indoors now, by the time your seedlings are big enough to transplant, the air and soil should be just the right temperature.
Root crops don’t transplant well, so directly seed carrots, beets, radishes, parsnips, etc. Don’t be tempted by seedlings in the nursery.
Start cucumbers, squash and melons in large pots now for transplant in a few weeks or seed them directly in the ground toward the end of the month.
Wait until next month to direct seed corn in the garden — it grows best with lots of heat.
Since our soils have very little organic matter, it’s better to grow vegetables in raised beds. Raised beds are also easier to reach and work in and they hold moisture better than soil.
Fill on-ground raised beds with a topsoil mix that’s 40% organic matter and 60% “dirt,” plus worm castings and organic granular vegetable fertilizer. Line the bottoms with hardware cloth (not chicken wire) to exclude hungry gophers.
Build your own on-ground raised beds. Watch my videos to see how build a raised bed: tinyurl.com/rsbed and plant a raised bed: tinyurl.com/plntbed.
My favorite free-standing raised bed is growing in a Vegepod (amzn.to/4iWRD4j), a stand-alone, prefabricated raised bed system with built-in irrigation. These waist-high beds work amazingly well for everyone, especially for people with back and knee issues.
Do NOT till your garden. Tilling appears to fluff up and soften soil but actually causes the soil to compact. Rototilling also destroys earthworms and the critical beneficial microbes that interact with plant roots to keep them healthy.
The best irrigation for raised beds is narrow in-line drip, such as Netafim Techline EZ, with emitters spaced every 6 inches. Shop for Netafim Techline EZ at your local irrigation store.
Make tomato cages from sheets of concrete reinforcing mesh held together on the short ends with zip ties. Fold the mesh to create a freestanding cylinder, about 3 feet in diameter —perfect for two tomatoes. These cylinders also support cucumbers, bean plants and other climbing crops. Watch this video from my Easy Seed Starting Online Course to see how: bit.ly/tomatocages.
Rotate crops. Tomato, pepper, eggplant and tomatillo are all susceptible to the same suite of soil pathogens. When you plant these nightshade plants in the same soil year after year, they produce less and less. Instead, set up garden beds in pairs, planting all nightshades in one of the beds the first year. Move them to the other bed in the second year. Move them to the original bed in the third year and continue that process.
Looking for varieties that resist root knot nematode or verticillium wilt or early blight or other common tomato problems? Check the variety descriptions for resistance codes like those listed at reimerseeds.com/DiseaseCodes.
Heirloom vs hybrid? Heirloom vegetables are popular for their flavor, but most are, sadly, short-lived since they have little to no resistance to common pests and diseases. “Old” hybrids were popular for their production and transportability, as well as their pest and disease resistance, but they often lacked in taste. Modern hybrids feature the best of both worlds, with better pest and disease resistance, high production and really good flavor. There are many more options now compared with two or three decades ago.
Flowers
My favorite flowers to cut now for bouquets:
• Fragrant, flowering sweet peas• Peruvian lilies (Alstroemeria)• Pincushion (Leucospermum)• Grevillea• Rosemary• Bearded iris• Forest lily (Veltheimia bracteata)• Clivia• Bugle lilies (Watsonia)• Roses• Daffodils and narcissus
What’s your favorite backyard cut flower?
Container gardens
A sunny balcony, patio or porch is the perfect spot to grow smaller, dwarf varieties of tomatoes, peppers, eggplants, etc. in containers.
• Tomatoes: Rosella, Tiny Tim, Super Bush, Stupice, Cherry Litt’l Bites
• Eggplants: Little Prince, Hansel, Gretel
• Peppers: Spice Trio Jalapeno, Bubba Jalapeno, Baby Belle, Pizza My Heart, Fire and Ice, Goat Horn
• Cucumber: Bush Slicer, Mini Munch Patio Snacker
• Summer squash: Bush Baby, Cash Machine
Unglazed terra cotta is the best choice in pots for vegetables, but if black plastic nursery cans are your only choice, drape them in light colored fabric so the intense sunlight doesn’t heat the pot, drive off the moisture and cook the roots.
Match the pot to the plants:
• A 15-gallon black nursery pot has room for one tomato plant or two pepper plants or eggplant plants or basil plants.
• A half whiskey barrel or wine barrel has room for two tomatoes or three peppers, or three eggplant plants, or three basil plants. Alternatively, plant three cucumber plants or one squash plant or five cilantro plants.
Geotextile fabric pots are easy to use but dry out super fast in our climate. In summer, water daily to keep the soil moist so plants don’t wilt. Some people set their fabric pots in a child’s wading pool, filled with a few inches of water to keep pots consistently damp.
Whatever pot you use, fill it with high quality potting mix — not planting mix, not backyard dirt, not pure compost. Don’t skimp on growing medium.
Fruit trees
Plant subtropical fruit trees now: citrus, avocado, guava, banana, papaya (along the coast only), jaboticaba, mango, coffee, etc. Group these thirsty plants together so they can be watered well without overwatering the rest of the garden.
Remove fruits from nectarines, plums and other deciduous fruit trees planted this year or last. Without fruits, they put their energy into growing strong roots and leaves instead. That makes for strong plants that support bigger crops in the future.
Thin marble-size fruits on mature stone fruit, apple and pear trees. Too many fruits on a branch make for small fruits. For larger fruits, thin to just one fruit along every 4 to 6 inches of branch. Compost the thinned fruits.
Feed stone fruits, apples and other deciduous fruit trees with organic fruit tree fertilizer. Feed citrus and avocado with organic citrus and avocado food. Always follow label directions.
Maintain
Turn over potted bromeliads and shake out the standing water in their “tanks.” Turn back upright and sprinkle Mosquito Bits granules into the center when you refill it. Mosquito Bits contain the biological pesticide Bt, which kills worms, caterpillars (so be careful with it around pollinator plants) and mosquito larvae.
Weed, weed, weed. Use a Cobrahead hoe or hand pull weeds by the root. Don’t bother spraying. By the time sprayed weeds die, they will have flowered and released seeds that will sprout next year. And besides, sprays aren’t good for the environment.
A thick, coarse, woody mulch over garden beds keeps dormant weed seeds from sprouting.
Better to used coarse, aged wood mulch than fresh chips. Fresh chips may come from borer infested trees. When you bring those onto your property, the deadly borers can infest and kill your trees, too.
Get a head start on heading off mosquitoes. Empty all bowls, dishes, buckets, and anything else that holds standing water. Decommission old fountains and plant them with succulents instead.
Irrigate responsibly
The goal of irrigation is to wet plant roots.
The best and most efficient irrigation for all plants is inline drip irrigation. Inline drip looks like long, narrow hoses with holes every 6 or 12 inches. Inside the lines, however, each hole connects to very sophisticated emitter that releases water one drop at a time.
Since inline drip releases water very slowly, it has to run a long time — 45 minutes, an hour, two hours or more — depending on your soil, the plants and how long it takes for water to penetrate down to plant roots.
To keep vegetable bed soils damp (not wet) at all times, you may need to run the irrigation two or three times a week through the early fall.
Water ornamental beds once every week to 10 days, allowing the soil to dry out in between. For mature, drought-resilient plants, natives and succulents, water just once every few weeks or even once a month. Always water deeply but infrequently.
Figure out how often to water each garden bed by using my Canary Test. Find the directions here: tinyurl.com/2p8bf7e6.
Mulch all garden beds with a 3-inch-thick layer of mulch. Match the mulch to the type of plant: straw mulch for vegetables; stone or rock mulch for cacti and other succulents; wood-based mulch (not bark chunks) for all other plants.
No matter the irrigation method, always water until the water penetrates all the way down to plant roots. After the irrigation runs, test how deep the water has gone by digging into the soil, using a soil probe, or sticking your finger as deep as it will go. Is it wet all the way down? If not, water more.
Sterman is a garden designer, journalist and the host of “A Growing Passion” on public television. She runs Nan Sterman’s Garden School at waterwisegardener.com.
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