Gadenin日本語Get the appThe year at a glance
Unlike a lemon or an orange, a citron does not give you a tidy season with a harvest at the end of it. Warmth drives everything: give it warmth and it flowers and sets fruit whatever the month, and take warmth away and it simply stops. Your calendar is therefore built around moving the tree and around holding the temperature, with picking and pruning fitted in around whatever the tree happens to be carrying.
| Season | The main job | Watering | Feeding |
|---|---|---|---|
| Early spring | Bring back out in stages once nights hold above 50F (10C); repot or root prune | Increase as growth resumes | Restart every two weeks |
| Late spring to summer | Prop fruiting branches, thin surplus fruitlets, watch for leafminer | Daily to every other day in heat | Every two weeks at full strength |
| Early autumn | Plan the move; clean pests off before it goes under cover | Ease off as nights cool | Last full-strength feed |
| Late autumn to winter | Under cover, cool and bright, above 50F (10C); fortnightly pest inspection | Every 10-20 days, by pot weight | Every four to six weeks, do not stop |
| Any season | Pick ripe fruit; remove rootstock suckers on sight | Never let the pot go bone dry | Flush the pot every couple of months in growth |
Spring: the move outdoors is the riskiest week of the year
Wait until nights are reliably above 50F (10C) before the tree goes back out, and then move it over a week or more rather than in one afternoon. Start in full shade, then dappled light, then morning sun, then full sun. A tree taken straight from a dim winter room into direct sun sunburns its leaves and any fruit it is carrying, and a fruit with a papery burnt shoulder is a fruit you cannot candy.
Early spring is also the window for repotting or root pruning, once every second or third year, before the strongest flush of new growth. Do that before the tree goes out, feed six weeks later, and expect a heavy flush of purple-tinged new shoots and flowers within a month of the move.
Summer: growth, weight and vigilance
This is when the tree does most of its work and most of your attention goes on the fruit already hanging. Check branch angles weekly and prop before anything bends past 45 degrees from horizontal. Thin fruitlets on slender branches down to what the wood can carry. Keep the pot out of drying wind, which rubs rind and tears leaves.
Water by weight rather than by schedule, feed every two weeks, and flush the pot with plain water every couple of months to clear accumulated salts. Leafminer trails will appear on the new flush in warm weather; ignore them entirely. Scale and mealybug are the ones worth acting on, and it is far easier to clear them outdoors than after the tree is shut in a room.
Autumn and winter: the whole point is not to lose the tree
Citron is the most cold-tender of the common citrus and it does not tolerate the frost that a hardier citrus shrugs off. Move it under cover well before the first frost, not after the first cold warning, and do it in stages over a week for the same reason you staged the move outward. Go over the tree for pests first, wiping stems and checking leaf undersides, so you are not sealing an infestation into a warm still room for five months.
Aim for a cool but bright position that stays above 50F (10C), ideally in the 50s F (10-15C). Cool and bright is far better than warm and dim; a warm dark corner makes the tree push weak growth it cannot support and then drop it. Keep water well down, judging by the weight of the pot, but never let it dry out completely, because there is fruit swelling on the tree even now. Keep feeding at a reduced rate for the same reason.
Expect leaf drop for two to three weeks after the move. That is adjustment, not disease, and it stops on its own. Inspect every fortnight with a torch.
Cold roots are the hidden killer indoors. A pot standing on a cold floor or against an outside wall stays much colder than the room, and roots below about 50F (10C) cannot take up water or micronutrients no matter how warm the leaves are. Stand the pot on a block of insulation or a thick mat.
The dates worth writing down
Five entries, kept year on year, turn this from guesswork into a routine you can trust. Record the date the tree went under cover and the date it came back out; those two frame everything else and drift by weeks from one year to the next. Record the date of each significant flowering wave and the date you cut each ripe fruit, because together they tell you how many months your tree takes from flower to usable rind in your conditions, which no general guide can tell you.
Record the date of every repot or root prune, since a two or three year cycle is impossible to judge by eye. Add the date you first found each pest, because those recur on a schedule tied to the move under cover, and one line in a notebook is what turns next winter's infestation into an inspection made weeks before it starts.