Think of citrus, and soon warm, sunny thoughts crowd your mind--with good reason. This collection of tree species and their hybrids thrive only in warm weather areas--southern parts of Zone 8, but most successfully in Zones 9 and 10. All varieties of oranges, lemons, limes, grapefruits, and tangerines are frost tender.
In borderline areas, develop a microclimate by planting citrus near a south or west wall, painting walls nearby a light color to reflect heat, and making a raised bed of railroad ties or concrete blocks (filling the space inside with improved soil).
Varieties
Pick from several important species of oranges. The common or sweet orange (Citrus sinensis) is most widely grown and includes the thick-skinned navels.
Orange varieties vary widely in their bearing season, so plant several to extend the length of time you can enjoy fresh squeezed juice. For example, you could try tending Washington, Hamlin, Pineapple, and Valencia--listed here in order of their bearing times. Most citrus varieties are self-fertile, so you can get fruit even if you have space for only one tree.
With an exotic red pulp, but no more difficult to grow, are the blood oranges; outstanding are Ruby, Torocco, Temple, Moro Blood, and French Perfume.
Grapefruit, most successful in desert-like regions, is available in pink and white. Marsh is an excellent seedless white; Foster and Ruby are pink and bear early in the season.
Tangerines, decidedly subtropical fruits, are small and easy to peel. Both Dancy and Fremont are hardy, but Fremont appears earlier (November), with Dancy in December.
Libson and Eureka (bearing most heavily October to May) are top lemons in California, but Meyer has the best cold tolerance.
Best known lime varieties include Persian (also called Tahiti) and Bears. Mexican is hardiest and can take temperatures down to 30 degrees Fahrenheit.
Planting
Good drainage and high temperatures are citrus trees' chief needs. Continuously soggy soil inhibits growth. The trees do need heat, but can get by in shade for part of the day.
Californians can plant citrus trees March to May, but Floridians set trees out somewhat later--spring and early summer. Plant trees no deeper than they grew at the nursery; the bud union should be about four inches above ground. If the young tree was not headed back at the nursery, prune it after Planting No more pruning is needed for a couple years. Rub off any young sprouts that appear beneath the bud union.
Wrap trunk in tree tape to prevent sunscald, and make a ridge around base to direct water toward roots. Young trees need deep waterings about every two weeks, but let the soil dry out between waterings.
Care and feeding
Citrus fruits do best in soils with a pH between 6.0 and 6.5. Take a soil test every few years, and apply dolomitic limestone when pH drops below 5.8. Fertilizer is applied three times a year, just before the appearance of new leaves. Only nitrogen will be needed in most parts of California, but nitrogen, phosphorus, and potassium may be needed in Florida.
Take care to deeply water even mature trees about every two weeks. Watering sufficiently to keep the lawn healthy isn't enough.
Insects and diseases
Usually an all-purpose spray will protect citrus against most hungry invaders. Spray in early spring, just after petal-fall, and again four to six weeks later. At the first flush of growth--late February or early March--spray for aphids with a mixture of 1-1/2 tablespoons of malathion per gallon of water. If thrips infest during hot weather, control them with the same mix used for the aphids.
Harvesting
Citrus specimens are ready for harvest for a long time. Often they can stay on the tree more than three months before becoming overripe. But, for peak flavor, pick fruits as soon after they mature as possible. Cut them from branches; don't pull them.
