Chinese banyan

Identification and origin

Ficus microcarpa (family Moraceae) has a very wide native range: from India and the Himalaya to southern China, Japan, Southeast Asia, New Guinea, Queensland and several Pacific islands.

It is an evergreen tree with a dense crown. The bark is smooth and gray; cut stems turn mustard yellow and bleed milky sap. The leaves are thick, leathery, glossy dark green, oval and short-pointed, usually 2–2 in long; they grow closer together than on most Ficus, making for very full foliage.

In warm, humid climates its dangling aerial roots become new trunks once they reach the ground: the classic banyan habit. In the ground it grows 2–49 ft depending on climate and age, and in Mediterranean climates it becomes a large street tree; in a pot it stays a shrub that can reach 13 ft.

Its flowers are hidden inside small figs about 0 in across, borne in pairs where the leaves meet the stem, and pollinated only by a wasp specific to the species. In Florida it began spreading by seed after that wasp was accidentally introduced in the 1970s; its seeds even sprout in sidewalk cracks. It is considered invasive in many parts of the world.

The ‘Ginseng’ form has a pot-bellied trunk and exposed swollen roots, sometimes topped with grafted branches. Other selections include ‘Golden Gate’ (gray trunk, popular for bonsai), ‘Green Island’ (deep glossy green), ‘Moclame’ (upright habit), the dwarf ‘Mini Flat Leaf’, and ‘Hawaii’, mottled with white.

Light

Plenty of light: full sun to partial shade. Indoors, keep it right by the brightest window, where it gets several hours of direct sun, within about 3.5 ft of the glass: light falls off very quickly with distance. The variegated ‘Hawaii’ prefers filtered light.

Too little light weakens it: new growth turns pale, then leaves drop. Once it is in a good spot, avoid moving it.

Watering

Water thoroughly when the top quarter to half of the root ball feels dry, then empty the saucer, using room-temperature water. The plant forgives an occasional slip, but not constantly soggy soil, which rots the roots, nor repeatedly drying out completely.

The warmer and brighter its spot, the more it drinks: go by observation, not a calendar. In winter, in a cool room, keep the mix just slightly moist. Underwatering yellows the leaves quickly; overwatering shows up more slowly.

It tolerates dry air but prefers more humidity: mist it in hot weather, without overdoing it, or set the pot on a tray of damp gravel. Aerial roots need humidity close to saturation, which is rare indoors.

Potting mix

A free-draining mix rich in organic matter that still holds some moisture: a peat-free, loam-based potting mix with fine bark added. Bonsai growers usually use a more mineral mix (see the bonsai guide).

From spring to late summer, feed about every four weeks with a high-nitrogen fertilizer. Stop in winter: too much fertilizer can also cause leaf drop.

Temperature

Most Ficus are happy between 61–84 °F; this one likes temperatures above 68 °F year-round, which is why it is usually grown indoors, and it cannot take frost. Keep it away from radiators, air conditioning and exterior doors: hot or cold air currents cause yellowing and leaf drop.

It can summer outdoors, sheltered from wind, as long as nights stay above about 59 °F. Once brought back inside it often sheds leaves and takes one to two months to adjust. Year-round outdoors, it is listed for USDA zones 9a–11b (winter lows above about 19 °F).

Repotting

Every two to three years in spring, once roots fill the pot, into a pot with drainage holes just slightly larger. In other years, replace about 1 in of the surface mix with fresh mix. It tolerates root pruning well at that time.

Pruning

It handles pruning well, even hard pruning, and resprouts from old wood. Prune in late winter or early spring, just above a leaf. For a dense shape, let a shoot grow six to eight leaves, then cut it back to two. On ‘Hawaii’, remove shoots that have reverted to plain green.

The sticky white sap that drips from cuts can irritate skin or aggravate allergies: wear gloves and protect the floor.

Propagation

• Cuttings: very easy, in water, sand or potting mix, using semi-ripe or leaf-bud cuttings; best results come in midsummer, with bottom heat.
• Air layering: in spring or late summer, wrapping a wound in the stem with moist sphagnum moss held in plastic film.
• Seed: in spring, if seed is available.
• Grafting: branches and roots fuse easily, which bonsai growers put to use.

Common problems

A single symptom can have several causes: check light, watering, temperature, humidity and any recent changes.

• Leaf drop: a stress response to low light, unsuitable watering, a move, a cold air current or too much fertilizer.
• Yellow leaves: unsuitable watering, low light or a change of location; a few old leaves yellowing now and then is normal.
• Pale new growth: not enough light, or a pot that has become too small.
• Cuban laurel thrips (Gynaikothrips ficorum): this small black insect marks young leaves with purplish-red spots, then folds them into pockets; they yellow and drop. It does not threaten the plant’s life but spoils its looks: cut off and discard affected shoots.
• Other pests: spider mites, mealybugs, scale insects and aphids, encouraged by dry air and low light.
• Diseases: root rot from overwatering, leaf spot and gray mold.

Toxicity

Toxic to pets: the milky sap of Ficus is irritating. If a dog or cat chews the leaves, it irritates the mouth and digestive tract (drooling, vomiting, diarrhea, loss of appetite), and it can irritate skin on contact. In people, too, it is a skin allergen. Keep the plant out of reach of pets and children, wear gloves when pruning it, and call a veterinarian if an animal eats any.