Ficus

Ficus microcarpa is a fig from the tropics of southern China, India and Malaysia, where it grows into a wide, spreading tree with a grey trunk, glossy leaves and the aerial roots that drop from its branches and thicken into extra trunks. Most of the ficus sold as bonsai are this species or its close relatives, under names that shift from shop to shop. "Ficus retusa" is the old label and still appears on tags. "Ginseng ficus" is a form grown for a swollen, bulbous root that is then potted high so that the roots stand as a trunk. The tiger-bark forms, with pale flecks on the bark and smaller leaves, are the ones most worth having, because they look like trees rather than root vegetables.

It is the right first indoor tree for a house because it tolerates what a house does to a plant. It copes with dry air better than any other indoor bonsai, it does not sulk for long when it is moved, it buds back readily from old wood, and it tells you clearly when it is unhappy by dropping leaves, then grows them again when the problem is fixed. Within a year a beginner can see the difference that pruning makes, which is the lesson that keeps people in the hobby. The warm, humid summer that a ficus would prefer is not something most rooms can offer, so growth is slower indoors than the books written for warmer places suggest, and that slowness is nothing to worry about.

The commonest mistakes are about light and water. A ficus wants the brightest window you have, ideally south or west facing, with the pot close to the glass; a tree set back on a shelf or on a north sill will thin out, stretch and drop leaves from the inside of the crown. Central heating is the other winter problem, not because of the warmth but because a radiator directly under the sill bakes the pot dry and cooks the roots on one side. Watering is where most trees are lost. The mix should be allowed to dry on the surface between waterings, then soaked through until water runs from the drainage holes; a pot kept wet in a cool, dark room in January will rot. The "ginseng" form bought from a supermarket, already in dense peat, is the hardest to keep going, and the sooner it is moved into a free-draining mix the better.

Through the year the tree lives on a bright windowsill from October to May. From roughly June to September it can go outside, in a sheltered spot with morning sun and shade from the hottest afternoon, once night temperatures are reliably above about 10 to 12 °C. It will grow more in those three months than in the other nine. Bring it back in before the first cool nights of autumn, usually early to mid September, and expect a few leaves to drop as it adjusts to the house. Keep it away from doors that open onto cold air and from the direct blast of a radiator.

A ficus grows from the tips and from any node that is cut back to, and it is not strongly dominated by its apex, so a crown can be built from the base up by pruning and letting it regrow. Shoots are pruned back to two or three leaves once they have extended to six or eight, and the leaves can be reduced in size by defoliating a healthy, vigorous tree in early summer, though a tree in a cool room rarely has the energy for that more than once in a season. Branches wire easily while green and set within a few months; older wood is brittle and the bark marks quickly, so wire is checked monthly. Cuts bleed a white latex that dries in minutes and seals the wound. Aerial roots appear in humid conditions and can be guided down into the soil to thicken the trunk base.

It is an evergreen, so there is no autumn show and no winter silhouette; the interest is the glossy leaf, the pale trunk, the surface roots and, on the better forms, the mottled bark. A healthy tree keeps most of its leaves all year and flushes with fresh, lighter growth in spring and again in late summer. If it flowers it does so almost invisibly, inside small figs that may follow in a warm year and should be removed so the tree spends nothing on them.

Repotting is a late spring job, when the days are long and the house is warm, every two years for a young tree and every three or four for an established one; the roots are pruned by about a third and the tree goes back into the same or a slightly larger pot. Feeding runs from spring to early autumn with a balanced liquid feed at half strength every fortnight, and stops over winter when the tree is only ticking over. None of these figures is a rule. Watch the tree, and let what it does in your room, in your light, decide.

• Informal upright (moyogi): the natural habit of a tree that is pruned back hard and allowed to regrow is a gently moving trunk with a rounded crown
• Broom (hokidachi): fine twigging develops quickly from repeated pruning, and the broad crown reads well on a short, stout trunk
• Root over rock (sekijoju): aerial and surface roots thicken fast and will grip a stone within a few seasons in a warm room
• Slanting (shakan): a lean towards the light is something a windowsill ficus does on its own; the style makes it deliberate
• Cascade (kengai): long, flexible shoots can be wired down while young, though the tree will keep trying to grow upward
• Forest group (yose-ue): rooted cuttings of one plant make a group of matched trees in a year or two

2 parts akadama, 1 part pumice, 1 part lava, with a small handful of composted bark if the room is dry (by volume)

A ficus is watered often indoors, so the mix must drain in seconds and still hold some moisture between drinks; the bark adds a little water-holding without the sogginess of multi-purpose compost.

A ficus takes a glazed pot, as the rule of thumb gives every broad-leaved tree, and a fairly deep one, because the roots are coarse and the tree is watered often. The length is about two thirds of the tree's height, or two thirds of the width of a broad, low crown; the depth is about the width of the trunk at the base, which on a root-potted ginseng form is the width of the swollen roots, so those trees sit in pots deeper than their height suggests.

Ovals and soft-cornered rectangles suit the rounded, informal crowns; a round or drum pot suits a single-trunk tree with a broom top. Glazes in cream, pale blue, sea green and a muted brown all work against the dark leaf; bright reds and blues fight it. A root-over-rock tree takes a shallow oval or a tray.

Indoors the enemies are the ones that like dry, still air. Scale insects sit as small brown bumps along the stems and the leaf midribs and are picked or wiped off with a cotton bud and diluted washing-up liquid, then watched for. Mealy bug shows as white fluff in the leaf axils and is dealt with the same way. Red spider mite arrives in a hot, dry room, stipples the leaves yellow and spins fine webbing; raising humidity and rinsing the foliage under the shower sets it back, and a soap or oil spray finishes it.

Sudden leaf drop is a response to change, not a pest: a move, a draught, a cold night by the glass, or a pot kept too wet. Fix the cause and the tree refoliates within weeks. Sticky leaves and sooty mould point to scale or mealybug above them.

What every month's line rests on: RHS H1b (https://www.rhs.org.uk/plants/32855/ficus-microcarpa/details, checked 30 Oct 2026): can be grown outside in summer, minimum 10 to 15 °C; a warm, bright room the rest of the year.