Ficus microcarpa as bonsai

Placement

In most temperate climates this is an indoor bonsai: it does not tolerate frost. It needs lots of light, ideally several hours of direct sun; keep it within about 3.5 ft of a bright window, because light drops off quickly with distance. It likes steady temperatures; avoid heaters and cold drafts.

It can spend the warm season outdoors as long as temperatures stay above about 59 °F. Its thick leaves let it cope with fairly dry air, but high humidity encourages aerial roots.

Soil mix

A free-draining, airy bonsai mix. A homemade mix of washed sharp sand and peat-free John Innes No. 3 works, as does a “basic” bonsai mix. What matters is that water runs through the pot without pooling.

Watering

Water by observation, not by the clock: once the surface of the mix starts to dry, water generously until it drains from the bottom, and don’t leave the pot sitting in water. The warmer it is, the more it uses; soft, room-temperature water is best. A ficus forgives the occasional missed or extra watering, but not a mix that stays soggy.

Feeding: every two weeks during growth, every four weeks in winter if growth doesn’t stop.

Pruning

Let six to eight leaves grow, then cut back to two. To thicken the trunk, let the tree grow freely for a year or two before a harder cut, which it handles well. Partial or full defoliation can reduce leaf size on vigorous trees. Cuts bleed white latex.

Wiring

Thin and medium branches are flexible and easy to wire, but wire bites into the bark very quickly: check it often and remove it before it cuts in. For thick branches, guy wires work better and can stay on longer. Use wire about one third as thick as the branch, wrapped at roughly 45°.

Repotting

In spring, about every other year, in bonsai mix. Ficus tolerates root pruning well. Afterward, keep it out of direct sun while it recovers.