Care for Bulbs
Spring bulbs are glorious now. After bloom is finished, it's okay to cut the flower stalk. Allow the leaves to turn brown and die back on their own, as they are storing energy for the bulb so it can bloom again next year. Keep soil somewhat moist, but not overly wet or the bulbs may rot. Layer several inches of compost around the bulbs. It will help maintain soil moisture, and as it breaks down it will add nutrients to the soil.
Sow warm-season herbs directly into the garden, including basil, garlic chives, and epazote. Transplant bay, salad burnet, lemongrass, marjoram, oregano, mint, rosemary, sage, and thyme. Herbs need extremely well drained soil, but it doesn't have to be as rich in organic matter as flower or vegetable beds. Nor do they need much in the way of fertilizer. Actually, they have better flavor and scent without growing in a rich environment. Herbs can take full sun.
Water and Fertilize Containers
Temperatures are warming and container plants need more attention. Water when the top inch or so of soil is dry. The plants will need more frequent fertilizer applications, as more watering will wash away nutrients. Follow package instructions for the type of fertilizer you use. Organic fertilizers and slow-release products work well for containers because they are released over a longer period of time. Allow water to drain out the bottom of the pot, leaching away accumulated salts.
Plant Citrus Trees
All types of citrus thrive in the low desert, including orange, grapefruit, pummelo, tangelo, mandarin, lemon, lime, kumquat, and limequat. Citrus is extremely frost sensitive so it isn't a good choice if you live at a higher elevation, although you might try a dwarf citrus in a container and move it indoors as needed. Semi-dwarf or dwarf trees are a better choice for a small landscape. Another option is a fruit cocktail tree, which has several citrus varieties grafted onto one rootstock.
Roses are in full bloom in April in the low desert. Keep them well watered and fertilized. Water should penetrate about 2 feet deep, and out past the dripline. Use a fertilizer created for roses or a balanced product, such as 10-10-10. Or, use a nitrogen source such as fish emulsion, blood meal or cottonseed meal and a phosphorus source such as bone meal. Potassium usually isn't lacking in desert soils. Apply several inches of mulch to maintain even soil moisture.