Gadenin日本語Get the appWater by weight and by finger, never by schedule
More potted citrus are killed by watering than by cold, and almost always by watering on a routine. A bergamot in a container in high summer outdoors may need a thorough soak every second day; the same tree in a cool bright room in midwinter may go three or four weeks between waterings. Any fixed interval will be badly wrong for at least half the year. Learn instead to judge the pot itself. Push a finger two inches (5 cm) into the compost: if it comes out damp, walk away. Better still, learn the weight of the pot when freshly watered and when it is ready for more, by tipping it slightly with one hand. Weight is the most reliable signal a container gives you.
When you do water, water properly. Fill the gap between compost and rim, let it drain through, and fill it again, until water runs freely from the base. A splash that wets the top inch trains roots into the surface layer and leaves the core dry, and a dry core in a peat rich mix becomes water repellent, so the next watering simply runs down the gap at the side of the pot and out of the bottom while the root ball stays dry. If a pot has reached that state, stand it in a tub of water for half an hour to rewet it from below.
Bergamot leaves give a usable warning but you have to read them the right way. Leaves that go slightly dull and hang limp with the pot light are thirsty and recover within hours of watering. Leaves that yellow, mostly on older growth, while the compost stays wet and heavy are the opposite problem, and reaching for the watering can then finishes the job. Cold wet compost in winter is the single commonest cause of a dead potted citrus.
| Situation | Watering approach | Warning sign |
|---|---|---|
| Outdoors in high summer heat | Thorough soak every one to three days, checked by weight | Wilting by mid afternoon and a pot that lifts easily |
| Outdoors in mild or wet weather | Check every three to five days; rain rarely wets a full canopy | A pot that stays heavy for a week; skip the watering |
| Just moved back under cover in autumn | Cut back sharply as growth slows | Yellow older leaves dropping while compost stays wet |
| Cool bright winter storage | Every two to four weeks, only when the top three inches (8 cm) are dry | Sour smelling compost and soft blackened roots at the drainage holes |
| Spring, as new shoots appear | Increase gradually as the canopy grows | New shoots wilting at midday means the root ball has gone dry |
Two feeding regimes, not one
Citrus in containers are hungry, and everything they get comes from you, since a limited volume of compost holds very little reserve and free draining mixes leach fast under regular watering. Feed through the growing season, from the first new shoots in spring until the end of summer, at every second or third watering with a balanced high nitrogen liquid citrus feed. Little and often beats a heavy occasional dose: a slug of concentrated fertilizer into a small volume of compost raises the salt concentration sharply and scorches the fine feeder roots.
From autumn through winter, switch to a low nitrogen winter formulation and feed perhaps once a month, or stop entirely if the tree is genuinely dormant in a cool store. This is not a minor refinement. Nitrogen pushed into a bergamot in low light and low temperatures produces long, soft, pale shoots with widely spaced leaves that are structurally useless and are the first tissue to die when cold or spider mite arrives. A tree fed hard through a dim winter emerges in spring looking drawn out and shabby, and the fix is a hard prune you would not otherwise have needed.
Never feed a dry pot. Water thoroughly, wait a few hours or until the next day, then feed. Fertilizer salts applied to dry compost concentrate against the roots and burn them, and the resulting brown leaf margins and dropped leaves look exactly like the deficiency people are usually trying to correct, which sends them back for another dose.
Yellowing between green veins on older leaves is magnesium, and it is very common in potted citrus because hard tap water and regular feeding lock it up. The same pattern on the newest leaves at the shoot tips is iron, usually caused by alkaline water or waterlogged compost rather than a genuine shortage. Diagnose by leaf age before you feed.
Moving the tree in and out without losing the leaves
The two moves a year are where potted bergamots most often go backwards, and the cause is always the abruptness of the change rather than the destination. A tree taken from a sheltered indoor winter and put straight into open sun and wind scorches its leaves within days. A tree taken from full outdoor sun and shut into a dim room drops a third of its canopy inside a fortnight. Both are shock responses to a step change in light, and both are avoidable by moving in stages over ten to fourteen days.
Go out in spring only once nights are reliably above about 45F (7C), and go in in autumn before nights fall below that. Do not wait for a frost warning, since the leaf damage that matters starts well above freezing. Before it comes indoors, look the tree over properly: check leaf undersides for scale and mite, top up the mulch or top dress the compost, and pick off anything dead. A pest carried into a warm dry winter space with no predators multiplies unopposed and you will meet it again in spring at ten times the number.
Indoors, keep the tree away from radiators, heaters and warm air vents. Dry moving air is what makes indoor citrus a spider mite problem, and a spot two feet (60 cm) from a heat source is an entirely different environment from one right beside it. Turn the pot a quarter turn every couple of weeks so the canopy does not lean towards the window, and keep the leaves clean, since a film of dust in already poor winter light is a real cost.
- Start the spring move in shade Put the tree outside for a few hours a day in bright shade, out of wind, once nights are above 45F (7C). Bring it back in each evening for the first few days.
- Add sun in increments Over ten days, extend the outdoor spell and move it gradually into morning sun, then full sun. Leaves grown under glass have no sun tolerance and pale bleached patches mean you moved too fast.
- Inspect thoroughly before autumn entry Check leaf undersides, stem joints and the fruit stalks for scale and mite. Treat with horticultural oil outdoors and let it dry before the tree comes in, rather than spraying inside the house.
- Reverse the process in autumn Move the tree into shade outdoors for several days first, then into the cool bright winter space. Expect some leaf drop even so; a tree losing a few older leaves is adjusting, one losing the lot is too warm or too dark.
- Reset the watering habit on the day it moves Watering frequency should change the moment the position changes, not a month later. Write the move date down so you remember that the pot in front of you is now on a completely different regime.
Fruit load, suckers and cleaning the leaves
Bergamot fruit is heavy for the size of tree and takes most of a year to develop, so a container grown specimen carrying a full crop is under a real load. On a young or recently repotted tree, thin the set to a handful of fruit and let the rest go. On an established tree in a big pot, leave what it sets and remove only fruit that is bending a branch or pressing against a thorn, since a thorn puncture in a swelling fruit rots and is the most common reason a good looking crop spoils on the branch.
Watch below the graft union all season. Bergamot is normally grafted, the rootstock is far more vigorous than the scion, and a shoot from below the union will be thornier, more upright and larger leaved. Left alone it takes the tree over within a few seasons. Take suckers off while they are green and finger thin, when they snap away cleanly. Once they are woody they need a saw and leave a wound on the trunk. A slow walk round the pot once a month, looking only below knee height, is two minutes well spent.
Finally, keep the canopy clean. Wipe the leaves with a damp cloth once or twice through the winter, both to remove dust that steals scarce light and because it is the most reliable way to notice scale and mite early, while numbers are still low. The leaves are aromatic and release scent as you handle them, which makes this one of the few genuinely pleasant jobs on the list.
The notes that make the second year easier
Keep four lines running: the dates the tree moved out and back in, the minimum temperature its winter space actually reached, the interval between waterings in each season, and the dates you fed and with which formulation. The watering interval in particular is personal to your pot, your mix and your climate, and no general figure will beat one season of your own observation.
Also note the date you first saw suckers and where on the trunk they emerged, and the date of any leaf drop with what had changed a fortnight earlier. Leaf drop always lags its cause, so the entry that explains it is the one from two weeks before, and without a written record you will attribute it to the wrong thing entirely.