Improve Garden Soil
Prepare soil for spring planting. Layer 4 to 6 inches of compost or well-aged manure on top of the soil. Add nitrogen and phosphorus fertilizer according to package instructions. If soil is heavy clay, add gypsum or soil sulfur. Dig in to a depth of 12 to 18 inches. If soil is hard and rocky, raised beds may be an easier way to go.
If you didn't feed citrus trees in January, provide one-third of their total annual nitrogen requirement. Fertilizer should be applied at the edges of the tree's canopy or dripline where feeder roots are actively growing. The amount to apply varies depending on the tree's size and how long it's been planted. A mature tree requires about 1-1/2 pounds of actual nitrogen per year, so apply 1/3 of that, about 1/2 pound of nitrogen.
Water Winter Lawns
Water should soak 4 to 6 inches deep for winter ryegrass, which has a more shallow root system than Bermuda. Water every 5 to 10 days, depending on rainfall, soil conditions, and weather. Water dormant Bermuda once a month, making sure the water soaks 8 to 10 inches deep.
Watch for Aphids and Cabbage Loopers
Aphids and cabbage loopers may start showing up on vegetables and tender new plant growth. Aphids are small, soft-bodied insects with sucking mouthparts. They leave behind a sticky honeydew residue. They are usually green or grayish black. Control them with a strong spray of water from the hose. Cabbage loopers are small green caterpillars with chewing mouthparts, so they leave holes or jagged edges. Loopers are easily controlled by handpicking. If you check plants daily to keep these insects under control, no pesticide should be needed. Also, beneficial insects, such as the larvae of lady beetles and green lacewings, will soon arrive to consume aphids for you.
Roses start their major bloom cycle in the low desert in April. Begin fertilizing bushes now to help prepare them. Use a fertilizer formulated for roses or an organic fertilizer that contains nitrogen and phosphorus. Most desert soils have sufficient potassium. Add 1/4 cup of epsom salts (magnesium sulfate) per bush to help prevent magnesium deficiency. Water soil well after application to prevent root burn. Fertilize every 6 weeks through the bloom season.