A cover crop of favas, fenugreek, buckwheat, oats, field peas, alfalfa and mustard greens will add organic matter back to the soil, fend off weeds and keep the earth from becoming compacted. Gardeners in areas with light frosts can spray an anti-transpirant (as is used on Christmas trees) on frost-tender trees and shrubs such as citrus trees, kiwi vines, avocado trees and bougainvillea, areas with heavier frosts should use old sheets, burlap, or specially designed frost covers when frost th...