Gadenin日本語Get the appThis is a real indoor bonsai, and most others are not
Most trees sold as bonsai are temperate species that need a cold winter and will slowly die in a heated room. The ginseng ficus is the exception. It comes from a warm, frost-free climate, has no dormancy requirement, and will grow all year at ordinary room temperature. If you keep it inside permanently in a bright spot it is not being kept badly, it is being kept correctly.
That does not mean it thrives anywhere indoors. A room that feels bright to a person is often deep shade to a tree, because our eyes adjust and a light meter does not. The tree will hang on for a long time in mediocre light, shedding a little, growing long thin shoots with big gaps between the leaves, and never thickening. That slow decline is the commonest way ginseng ficus are lost, and it is entirely a placement problem.
How much light it actually needs
Aim for the brightest window in the house with the tree close to the glass, within two feet (60 cm). An east-facing window with a few hours of gentle morning sun is close to ideal. A south-facing window works if you filter the harshest midday hours with a sheer curtain, because leaves that grew in low light will scorch if you suddenly hand them full sun. North-facing windows are usually not enough on their own.
| Position | Verdict | What you will see |
|---|---|---|
| Right at an east window | Best | Compact growth, small leaves, steady canopy |
| South window behind a sheer curtain | Very good | Fast growth, needs pinching more often |
| Unfiltered south window in summer | Risky | Pale bleached patches on leaves facing the glass |
| Six feet (1.8 m) back from any window | Too dark long term | Long shoots, wide leaf spacing, slow leaf loss |
| North window only | Marginal | Survives, does not thicken, thins each winter |
| Under a desk lamp with no daylight | Not enough | Steady decline over a season |
A quick test at midday: hold your hand a foot (30 cm) above the canopy. A shadow with a crisp edge means enough light. A soft gray smudge with no defined edge means the tree is short, whatever the room looks like to you.
Temperature, drafts and dry air
Keep it above 60F (16C) and it grows. Between 50F and 60F (10C to 16C) it stalls and sheds. Below 45F (7C) it starts losing branches, and frost kills it outright. The number that matters is not the room average but the temperature at the pot, next to the glass, on the coldest night. A windowsill can be twenty degrees colder than the middle of the same room after dark in winter.
Moving air is the other trigger. A draft from a front door, the downdraught from an air conditioner and the hot dry blast from a heating vent all cause leaf drop, and the draft version is the confusing one because the leaves fall green with no yellowing first. Stand where the pot will go on a cold day and feel for air movement at pot height before you commit to the spot.
Dry winter air from central heating will not kill the tree but it does make the leaf edges crisp and it strongly favors spider mites. A humidity tray, or grouping the tree with other plants, is enough. Misting the leaves does almost nothing that lasts more than a few minutes.
Summer outdoors and the two moves that cost you leaves
A ginseng ficus put outside for the warm months in a bright, sheltered spot with shade from the hottest sun grows noticeably faster and thicker than one kept in all year. It is worth doing if you can, but both ends of that trip are a light change, and a light change is what makes this tree shed.
Take it out only once nights are reliably above 55F (13C), and bring it back in before nights fall below 55F (13C) in autumn, not after. Do not put it straight into full sun; give it a fortnight in bright shade first, then increase the sun gradually, or the nursery-soft leaves will burn.
- Move it out in stages over two weeks Start in full shade outdoors, then dappled shade, then morning sun only. Each stage for three or four days. Skipping this is how people get a tree that scorches in the first afternoon and then sheds the lot.
- Expect faster drying outdoors Wind and sun can take a small bonsai pot from wet to bone dry in a single hot day. Outdoors in summer you may be watering daily rather than weekly, so check every morning rather than keeping to an indoor schedule.
- Check for hitchhikers before it comes back Inspect leaf undersides and the branch crotches for scale, mealybug and mites and deal with them outside. Anything you carry in will spread through the house over winter, when dry warm air suits them perfectly.
- Accept one shed on the way back in Even done well, the return indoors usually costs some leaves as the tree rebalances to lower light. Cut the watering back at the same time you bring it in, and do not feed until the new leaves open.
Rotation, and what to keep a note of
Give the pot a quarter turn every couple of weeks so the back of the tree gets the same light as the front. Without it the shaded side thins out and you end up with a tree that has a front and a bald back, which no amount of later pruning fixes quickly. Mark the front of the pot with a small dot so you know where the intended viewing side is when you turn it.
Worth recording: the exact position the tree is in, the date you moved it out for summer and back in for winter, and the coldest reading you get at the pot in midwinter. If a shed follows a move, the notes tell you within seconds whether the cause was light, cold or nothing but the calendar. Over two or three years those dates settle into a routine you can trust rather than re-deciding each season.