Phoenix palms belong to a very large genus of plants, some of which produce edible fruit. Phoenix dactylifera is the commercial source of the date, although other members of this family are simply grown for their ornamental qualities. Despite the fact this group of palms is native to warm climates, they can even be grown in colder areas.
Phoenix canariensis is one of the most architecturally grand date palms. This massive trunked palm develops a lush crown with elegant fronds. Growing up to 40 feet tall in warm climates, this plant does need adequate space. Pruning is required once a year to remove dead fronds, and care should be exercised to avoid the sharp spines. This date palm is hardy in USDA zones 9 through 11, but it may also be grown in zone 8 as well if the plant is given winter protection for the first few years.
Phoenix dactylifera is the date-producing variety of phoenix palm. However, at least one male palm for every five to 10 females is required for proper pollination and fruit production. Some areas with shorter growing seasons may never see ripe fruit, but this palm is worth growing for its appearance alone. Growing up to 100 feet tall, Phoenix dactylifera definitely makes a statement in the garden. A yearly pruning should be done to remove dead fronds. This palm produces suckers from the roots, which should be removed to tidy up the form. Zone 8 gardeners may have some success growing this palm, but it is really more appropriate to zones 9 through 11.
Actively growing date palms will have extremely deep root systems, which makes them somewhat drought tolerant once fully established. Regular summer water will keep the crown full and lush. These palms will happily grow in even poor soil, as long as it is well-drained. A light sprinkling of agricultural lime around the base of the trunk in early spring will provide some of the alkalinity this plant needs. In fact, yellowing of the leaves is usually not caused by lack of soil fertility, but by an overly acid soil. Soil too far on the acid side makes it difficult for palms to process existing soil nutrients. Fertilizers made exclusively for palms often have added lime.
Pruning should be done once a year. New fronds will emerge every season, replacing the old, which will dry up and hang unattractively on the plant. All phoenix palms have spines at the leaf bases, so heavy gloves and eye protection should be worn. Eventually, the palm will reach a height that makes pruning impossible.
Phoenix palms are reliably hardy in zones 9 through 11, but gardeners in colder zones have found hardiness varies depending on care and location. For marginal zones, planting the palm in the hottest, sunniest area of the yard and providing winter protection the first few years will allow some success. Young palms are more easily damaged by cold than older specimens. A double layer of frost blankets when temperatures are especially chilly will provide some protection. Building a miniature plastic greenhouse with a vented top to prevent overheating is another option. Soil drainage is crucial for winter hardiness. The combination of severe cold and soggy roots can cause root rot and death.
These are very large palms and should be planted as either a focal point, or to draw attention to a larger architectural feature, such as bracketing a long driveway or a yard entrance. They should not be grown too close to high traffic areas, as the fronds that are shed every year have wicked spines. In marginal growing zones where hardiness is an issue, most phoenix palms will grow very slowly, never reaching their maximum height, which means they can be planted closer to existing structures.
Root rot is the most common problem, caused by poorly drained soil. Leaf spot and other mild fungal diseases can cause cosmetic damage, but are usually not enough to kill the palm. Yellowing fronds are usually the fault of acidic soil, which can be remedied by applying agricultural lime or a commercial palm fertilizer containing it. Fronds that develop brown edges indicate inadequate water, which usually occurs with young plants that have undeveloped root systems.