Pomegranate

Identification and origin

Punica granatum belongs to the Lythraceae family. It is native to a region stretching from northeastern Türkiye to Afghanistan and Pakistan, by way of the Caucasus, Iran, Iraq and Central Asia. Grown since the most ancient civilizations of the Middle East, it spread to India, China and then all around the Mediterranean; Spanish missionaries carried it to Mexico and later to California. Today it is naturalized in many warm regions of the world. Its English name, pomegranate, means “seeded apple.”

It is a dense, bushy, multi-stemmed deciduous shrub that sends up many suckers from its base. Its slender twigs are sometimes thorny. The leaves, opposite or clustered, narrow and oblong, glossy dark green, measure 1–4 in and turn yellow in fall. The bark, gray-brown and smooth on young plants, becomes furrowed and flaky with age.

The trumpet-shaped flowers, with petals crinkled like crepe paper, are about 1 in across and open at the branch tips from early summer into fall. Most often orange-red, they can also be pink, yellow or white. The fruit, a slightly flattened sphere with smooth, leathery skin, 2–4 in across and pinkish-yellow to purplish-red, holds hundreds of seeds wrapped in juicy pulp, the arils, which are the edible part.

In the ground, pomegranate usually reaches 5–12 ft tall, more when trained as a tree. The dwarf cultivar ‘Nana’ stays around 3 ft; its fruit is not edible. ‘Wonderful’ is the most widely grown fruiting cultivar.

Light

Give pomegranate full sun in a warm, sheltered spot facing south, west or east. It tolerates partial shade but flowers and fruits far better in direct sun. Under glass, give it full light and shade it only from the harshest sun.

Watering

Once established, pomegranate withstands long dry spells, but it then produces little fruit. For a good crop, keep the soil evenly moist throughout the growing season: water thoroughly when the surface has dried, then let the excess drain away. Pay special attention in late summer and early fall, when uneven watering makes the fruit split. In a container, check the mix more often, because the root ball dries quickly in summer.

In winter, when the tree is leafless, water sparingly: just enough to keep the root ball from drying out completely. Waterlogged soil encourages root rot. Go by the feel of the soil rather than the calendar.

Potting mix

Pomegranate is not fussy: it accepts clay, loam or sandy soils, acidic, neutral or alkaline, as long as they drain well. It prefers deep, moist, slightly acidic, fertile soil. Poor drainage or very alkaline soil is tolerated, but growth and yield suffer.

In a container, use a large pot with drainage holes and a peat-free, loam-based mix. During growth, apply a balanced liquid fertilizer once a month. In the ground, a little extra nitrogen in fall or winter is beneficial.

Temperature

Pomegranate loves heat. It needs only a short chilling period in winter, but it is sensitive to fall and spring frosts, which damage young shoots. For the fruit to ripen it needs a warm fall, with temperatures around 55–61 °F; in cool climates, pomegranates seldom ripen.

In the ground it tolerates moderate frost in mild, sheltered areas and usually survives the winter, but it is killed to the ground below 10 °F. It is grown in the ground in USDA zones 8a to 10b. Elsewhere, grow it in a container and bring it into a cold but frost-free place for winter, or plant it against a warm, sheltered wall.

Repotting

Plant or repot in spring, before the buds break. A potted pomegranate is repotted every two to three years into a slightly larger container with fresh loam-based mix. It tolerates root pruning well. Choose a stable pot with good drainage.

Pruning

Flowers form at the tips of new shoots, and pomegranate fruits on both young and older wood. Prune lightly from spring to summer to keep a balanced shape. During the first years, build a stocky, compact framework; open the center by removing low interior shoots to let light in, which improves fruit flavor. Every year, remove suckers from the base and old, unproductive wood.

To get a small tree rather than a shrub, let it grow freely the first year; in the second year, select four to six strong stems to form the framework and regularly remove the other suckers. It also suits wall training and bonsai.

Propagation

Sow seed in spring at 55–64 °F. Semi-hardwood cuttings root in summer with bottom heat. Hardwood cuttings in spring, before bud break, root cuttings and air layering also work. Pomegranate is self-fertile: a single plant is enough for fruit, although two trees growing near each other improve fruit set.

Common problems

• No fruit, or fruit that fails to ripen: too little sun, a summer or fall that is too cool, a humid climate that hinders pollination, or prolonged drought.
• Split fruit: uneven watering or late-season rain.
• Spots on leaves and fruit: leaf spot and fruit diseases, favored by humidity; affected leaves turn pale and drop.
• Insects on leaves and twigs: aphids, whiteflies, scale, mealybugs or caterpillars.
• General decline: root rot in waterlogged soil, or Armillaria root rot.
• Damaged young shoots: late spring frost or early fall frost.

The same symptom can have several causes: always check light, watering, drainage and recent temperatures before acting.

Toxicity

No toxicity is reported for pomegranate: it does not appear among the plants listed as toxic to dogs and cats. The arils are edible, raw or juiced, and grenadine syrup is made from them. The fruit of the ornamental cultivar ‘Nana’ is not eaten.