There can never be enough reminders to set out those tomato plants! Mid-February to mid-March is the time to transplant tomatoes and peppers in the low desert. Don't delay, or plants won't have time to establish, flower, and set fruit before summer heat. If you're at a higher elevation, wait until your last average frost date. Add generous amounts of compost to the bed and mix a phosphorus source into the bottom of the planting hole. Phosphorus promotes flowering and fruiting, and since it doesn't move readily through the soil, it should be placed where the roots will be.
Rain a few weeks ago germinated cool-season weeds. They take off with great vigor. Stop them before they get out of control and rob your plants of nutrients and water. The green foliage is a great source of nitrogen for the compost pile. Don't let weeds flower and set seed, and don't put any seed heads in the compost.
Check Annuals for Nitrogen Deficiency
Check vegetables and flowers for signs of nitrogen deficiency, which appears as yellowing leaves on new growth (found at the tips of branches or the plant). Apply a nitrogen fertilizer, such as blood meal or fish emulsion. Vegetables that are heavy nitrogen users, such as salad greens and members of the cabbage family, may benefit from a side dressing of nitrogen, depending on your soil fertility. Don't apply too much nitrogen to root crops or flowers, or you will encourage overly abundant foliage growth.
Transplant borage, chives, lemon grass, oregano, and thyme. Divide chives, lemon balm, lemon grass, mint, and yarrow. Add some organic matter to the soil, but herbs do not need heavily enriched soil or fertilizer. They require excellent drainage. If there is a lot of clay in your soil, amend it with plenty of organic matter, small amounts of sand, and gypsum or soil sulfur to improve drainage.
Watch for Cabbage Loopers
Cabbage loopers are about one-half inch long green caterpillars that make a little arch or loop with their bodies as they crawl, hence their common name. They may be found on many vegetables, especially members of the cole family, such as cabbage, cauliflower, broccoli, kale, and bok choy. They have chewing mouthparts, leaving ragged-looking holes on foliage. Handpick them and destroy. No pesticide should be needed if you patrol regularly.