Replace cool-season annuals with sturdy bloomers that can take the heat; for example go with celosia, marigold, verbena, salvia, and petunia. Direct-sow cosmos, cleome, sunflowers, and zinnias right into the garden for easy-growing cut flowers.
Enjoy the pleasures of growing your own food! In your diverse region, what you plant depends on where you garden.
Low Desert: Set out seedlings of tomatoes, eggplants, and peppers. Direct sow seeds of beans, cucumbers, squash, melon, and okra.
High Desert: Sow quick-maturing radish and lettuces, or set out seedlings of broccoli, cabbage, chard, or cauliflower. Frost is still a possibility. Wait another 2-4 weeks before planting warm-season crops. Check with a garden center to confirm your local last frost date.
Trees and Shrubs
Continue to plant container-grown trees, shrubs, perennial herbs, groundcovers, and perennial flowers. In the desert, finish planting this month.
Test Garden Tip: Soil needs to be 60F for heat-loving crops like tomatoes and peppers. If you don't have a soil thermometer, you can tell when it's warm enough by walking on it barefoot. If you're not scampering along because of the chill, it's good to go. Soil typically reaches this temperature about two weeks after the last average frost date.
Fertilize roses, citrus trees, fuchsia, avocado trees, and irises.
Keep an eye out for iron deficiency on citrus, camellia, and gardenia. It shows as yellow leaves with green veins. Fix the problem by fertilizing with a product containing chelated iron.
If olives drop and stain surfaces, prevent fruit formation by spraying trees with a fruit-control hormone. Spray as soon as white blooms appear. Or skip the chemicals and remove the flowers with a strong blast of water from a garden hose.
Get mulch in place before summer heat arrives. Use a 3-inch layer of organic matter, like forest mulch, bark chips, or compost. Mulch helps soil retain moisture, lowers soil temperature, and, if it's organic matter, improves soil as it breaks down.
Keep up with watering. At this point in the season, it's important to pay special attention to any newly planted plants, containers, roses, and lawns. Tomatoes and globe artichokes also need consistent watering for best fruit production.
For best water use, irrigate around established plantings once the soil is dry about 6 inches below the surface. Use a screwdriver to poke a hole in soil so you can check dampness.
Consider installing a drip irrigation system for your containers. It makes watering a hands-free chore, which is a boon as temperatures climb.
Test Garden Tip: As temperatures rise, adjust irrigation timers to deliver the same amount of water more frequently. By increasing the number of days per week the system operates -- and not the number of minutes per cycle -- you'll limit runoff by delivering just the amount of water soil can absorb.
Aphids cluster on tender new growth. Knock them off with a blast of water from the hose. They're not quite bright enough to regroup and attack again -- but new generations will appear. Remain vigilant.
Continue to control snails as needed. Use pet-safe baits and hand-pick snails.
In dry conditions, spider mites flourish. Bring populations under control by spraying affected plants daily with a strong blast from the hose. Direct the spray underneath leaves. This will also reduce aphid populations.
Test Garden Tip: If you spot ants trailing up and down plant stems or trunks (like citrus trees), halt the parade with a sticky trap or surround the base of the plant with boric acid traps.
Fertilize the lawn if you didn't do so last month.
Mowing at the right height helps keep turf thick and healthy. Time mowings so you're only ever removing one-third of total blade growth. Follow this guide to mowing height.
Fine fescue: 1-1/2 to 2-1/2 inches
Kentucky bluegrass: 1 to 2-1/2 inches
Perennial ryegrass: 1 to 2-1/2 inches
Tall fescue: 1-1/2 to 3 inches
Bermudagrass: 1/2 to 1-1/2 inches
Buffalograss: 1-1/2 to 4 inches
St. Augustine: 1 to: 3 inches
Zoysia: 1/2 to 2 inches