Ficus retusa

If you don't have outdoor space and want a real bonsai (not a juniper that you'll watch decline for a year), Ficus retusa is the right answer. The species is genuinely well-adapted to indoor conditions: it doesn't need cold dormancy, tolerates lower light than most tropicals, handles dry indoor air better than most ficus species, and produces aerial roots that develop into character features over a few years.

The "Ginseng ficus" you'll see at every garden centre and supermarket is the same species — F. microcarpa, sold as F. retusa — but mounted as a graft onto a bulbous Ficus ginseng rootstock. These are mass-produced in tropical nurseries and shipped flat-packed. The grafted form isn't ideal long-term (the graft union rarely looks elegant as the tree matures) but it's an inexpensive way to start, and the foliage portion can be propagated into a much better-shaped tree over time.

Ficus is the bonsai species where impatience is least punished. They grow fast, back-bud reliably, recover from over- and under-watering, accept hard pruning, and forgive most beginner errors.

Water when the surface of the substrate has dried — typically every 2–3 days indoors in winter (when central heating dries the air), every 1–2 days in summer or near bright windows. Ficus is forgiving of inconsistent watering; brief dryness causes some leaf yellowing and drop but the tree recovers.

When you water, water thoroughly until it runs from the drainage holes. Drain any standing water from the saucer.

The species' single most common problem is winter leaf drop from sudden environmental changes — moving from a bright window to a darker spot, central heating turning on, a draught from a door. None of these are emergencies; the tree adjusts within a few weeks.

Year-round feeding, but reduced in winter. Liquid feed every two weeks from April through to October at half strength; monthly through winter at quarter strength. Slow-release organic pellets in spring and summer.

Ficus is a vigorous feeder when growing actively (April through October, when it's effectively summer indoors with good light). In winter — low light, shorter days — growth slows and feeding should reduce accordingly.

A common error is to stop feeding entirely in winter, then resume at full strength in spring. The tree responds with a burst of leggy growth. A gentler reduction through winter and gradual increase through spring produces tighter growth.

Free-draining but slightly moisture-retentive. Ficus tolerates a wide range of substrates.

Repot every 2 years on young vigorous trees, every 3–4 on mature specimens. The window is essentially year-round when grown indoors — ficus doesn't have a true dormant period and can be repotted whenever convenient. Late spring (April–May) is most traditional and gives the strongest recovery.

The species tolerates aggressive root work. Up to half the root mass can be removed on healthy trees. Bare-rooting is possible if necessary. After repotting, keep the tree in slightly lower light for a week or two and water carefully until new growth confirms recovery.

Ficus pruning is the easiest in bonsai. The species back-buds reliably on old wood, tolerates hard chops, and produces aerial roots from pruning wounds in humid conditions.

Through the growing season, let new shoots extend to 6–8 leaves then cut back to 2. Pinch every 2–3 weeks in active growth. Trees in development can be allowed to run longer.

Major structural pruning happens at any time the tree is actively growing — typically May through September. Don't be precious. A ficus cut back hard will be pushing new buds within 2–3 weeks.

A specific ficus technique: cuttings from prunings root easily. A heavy pruning session can produce a dozen propagules for free.

Wire after leaves harden in late spring or on bare wood any time. Bark is forgiving — better than maple, similar to elm. Branches are flexible and take wire well. Aluminium for most work.

A particular feature of ficus: branches will sometimes thicken so quickly during a growth flush that wire bites in within weeks. Check fortnightly during active growth.

Almost any style. Informal upright, banyan-style with aerial roots, root-over-rock, and forest plantings all work well. The species' tropical character makes it particularly suited to styles that wouldn't work for temperate species — dense tropical canopies, multiple trunks with merged bases, and aerial root features that read as banyan-like maturity.

Aerial roots can be encouraged by high humidity and selective wounding. They're a defining feature of refined ficus bonsai and worth developing.

Indoor permanently. Minimum temperature 10°C — keep away from cold windows in winter, draughts from doors, and unheated rooms.

Light: bright indirect to direct light is ideal. South-facing window with a sheer curtain in summer, full south-facing winter sun. The species tolerates lower light than most ficus but doesn't thrive in it.

Humidity: indoor humidity in heated UK winter rooms is low (often 30–40%). Ficus prefers higher humidity (50–70%). A humidity tray (pebbles, water) under the pot, regular misting, or grouping with other plants all help.

Some growers move their ficus outdoors for the UK summer (mid-May through to mid-September). This produces stronger growth and tighter foliage but requires careful re-acclimation in both directions to avoid leaf drop.

Easy from cuttings — almost any pruned branch will root in water or moist substrate. Air layering works exceptionally well and is the best route to a refined trunk on a new tree. From seed possible but rarely used.

Generally healthy when grown correctly. Most problems are environmental (light, humidity, temperature) rather than pest or disease.