Desert soils contain about 1% of organic matter. Desert plant life doesn’t drop much litter to decompose and build up in the soil, so we need to help. Compost is the gardeners’ gold. Dig in and loosen the soil to a depth of 12 to 18 inches. Most annual vegetable, flower, and herb roots grow about 12 inches deep, so loosening allows the roots to easily penetrate. If your soil is too hard or rocky to dig, raised beds are a good option. They work best if they are at least 18 to 24 inches deep. Layer 4 to 6 inches of compost on top of the soil. Regardless of soil type, compost improves fertility and attracts earthworms, which are great soil-builders.
• Erect temporary shade covers for vegetables that you want to encourage to produce this fall, such as tomatoes and peppers.
• Sow seeds or transplants for borage, chamomile, chervil, chives, cilantro, dill, fennel, lemon balm, parsley, salad burnet, and French sorrel. Now is also a good time to plant lavender, lemongrass, lemon verbena, oregano, mint, sage, and thyme.
• Sow seeds for peas, root crops (beets, carrots, kohlrabi, onions, turnips), and green leafy veggies (arugula, Asian greens, chard, lettuce, mustard, and spinach).
• Sow seeds or transplants of cabbage family crops, including cabbage, cauliflower, broccoli, kale, Chinese cabbage, Brussel sprouts and bok choy.
• Deadhead flowers of summer-blooming annuals to encourage a longer flowering period. Toss the trimmings into the compost pile.
• Keep your potted plants, including succulents, shaded from the afternoon sun.
• Bulbs can be planted from late September through November in the low desert. (At higher elevations, plant before cold temperatures set in by mid to late October.) Before planting, incorporate plenty of organic matter into the soil to improve drainage and fertility. Add a phosphorus source, such as bone meal or bulb fertilizer, into the bottom of the planting hole. If gophers are a problem, encase bulbs in wire mesh cages.
• Lightly prune roses to ready them for their second bloom period of the year. Fertilize with compost tea. Water deeply for mature roses. Refresh the mulch around the shrub if needed, keeping it away from the base of the bush.
• Sow seeds for alyssum, bachelor’s buttons, calendula, coreopsis, hollyhocks, Johnny-jump-ups, larkspur, nasturtiums, pansies, and poppies.
• Set out transplants for baby’s breath, petunias, stocks, dianthus, snapdragons, yarrow, and geraniums.
• Water your trees at the drip line. Water must soak down three feet to get to the roots, so water deeply if rain doesn’t provide.
• If you didn’t fertilize citrus in August, do so now. (This is our last citrus feeding for the calendar year.) Fertilizer should be applied slightly beyond the tree’s canopy. This is where the feeder roots that take up water and nutrients are located. Fertilizing near the trunk of a mature citrus is not helpful.
• Fall is the preferred planting time for trees and shrubs. They will have about eight months of moderate temperatures for root development before summer’s intense heat.
• No fertilizer is needed for most landscape trees until they have been growing for a year. Many native plants never require fertilizer as they are well-adapted to soil and environmental conditions.
• If over seeding your bermudagrass with winter rye, stop fertilizing four to six weeks in advance, but continue watering normally. Water should soak 8 to 10 inches deep. Mow bermuda progressively lower until reaching 1/2 inch. If you prefer not to over seed, continue your normal maintenance routine.