Gadenin日本語Get the appThe year at a glance
A lemon in a container has two axes: the growth cycle, which runs on light and temperature, and the fruit cycle, which is six to nine months long and therefore overlaps itself. The calendar below assumes the tree summers outdoors and winters under cover, which is how most people outside the subtropics grow one.
| Season | Feed | Water | Main jobs |
|---|---|---|---|
| Late winter | None until growth starts | Sparingly, when dry 2 in down | Prune, remove suckers, root prune if due |
| Early spring | Start high nitrogen citrus feed | Increase as growth starts | Harden off and move outdoors over two weeks |
| Late spring | Every 2 weeks | Most days in warm weather | Main flowering, oil sprays on new flush, thin heavy fruit set |
| Summer | Every 2 weeks, high nitrogen | Daily in heat, check by weight | Watch for scale, shade the pot, tie in or shorten water shoots |
| Early autumn | Switch to low nitrogen, then stop | Reduce | Inspect for pests, plan the move indoors |
| Mid autumn | None | Reduce sharply | Move indoors before nights hit 41F (5C) |
| Winter | None | Every 2-3 weeks in a cool room | Keep cool and bright, harvest ripe fruit, watch for spider mite |
Spring: the flush that makes the year
Everything good about a lemon year happens in a six week window in spring. The tree makes its main growth flush and its main flowering at the same time, and both depend on the tree going into spring with roots that are warm, unwaterlogged and not starved.
Feed as soon as you see new shoots extending, with a citrus feed high in nitrogen, every two weeks. Move the tree outdoors gradually once nights hold above 45F (7C), starting in shade. Prune before all of this, not during it.
Expect a heavy natural fruit drop three to six weeks after flowering. The tree sets far more fruitlets than it can carry and sheds most of them. This is not a failure, and it is not something to correct. If the tree is still carrying more fruit than it has leaves to support after the drop, thin by hand to roughly one fruit per twenty leaves.
Summer: water and vigilance
Summer is mostly water management. A lemon in a 16 inch (40 cm) pot in full sun can want watering every day at 85F (29C), and letting it dry hard causes fruit drop and split fruit later. Check by lifting the pot rather than by looking at the surface.
Shade the pot itself, not the tree. Compost temperatures above 95F (35C) damage roots, and a dark plastic pot in direct sun gets well past that. Stand it behind a low plant, wrap it in light cloth, or slip it inside a larger empty pot.
Scale insects build through summer. Look at the undersides of leaves and the joints where leaf stalks meet stems for small brown or white bumps, and check for sticky leaves and black sooty mold, which is a mold growing on the honeydew the scale excretes rather than a disease in its own right. Wipe off small numbers with a cloth and treat larger infestations with horticultural oil in the evening. Do not remove ants and expect it to fix itself, but note that ants farming the scale will undo your work if you leave them.
Autumn and winter: slow it down deliberately
The autumn job is to stop the tree growing before you move it. Switch off the nitrogen by late summer so the last flush hardens, and reduce water. A tree carrying soft new growth into a dim room loses that growth and often more.
Move it in before the first frost, in stages if you can. Winter it cool at 41F to 55F (5-13C) and as bright as possible. Water every two to three weeks, not on a schedule but on the weight of the pot. Do not feed, do not repot, and do not move it around; a lemon settles to one winter position and objects to being shifted.
Fruit that set in spring finishes over this period. Pick as it ripens rather than all at once, and keep checking leaf undersides monthly for spider mite, which explodes in dry indoor air.
The four dates worth writing down
The whole calendar collapses into four dates, and if you record only these you can run the tree properly from the second year onwards. Write down the day you moved it out, the day the first flowers opened, the day you moved it in, and the day you picked the first ripe fruit.
The gap between the first two tells you whether you moved out too late. The gap between flowering and first pick gives you your tree's own ripening interval. The move-in date, compared against when your first frost actually arrived, tells you whether you cut it too fine. Add a line on how many fruit you picked and any leaf drop after the move, and by the third year you are working from your own data rather than general advice.
Also record the pot size and the date of the last repot. Once a lemon is in its final pot it is easy to lose track of when it last had its roots pruned, and going four or five years without produces a tree that dries out in hours and stops fruiting.