Shikuwasa Growing Calendar: What to Do Through the Year

The five events the year hangs on

Run the year off events you can see rather than off dates, because the events move with your climate and a calendar does not. The first is the spring flush, when the buds break and new leaves push, and that is your signal to start feeding. The second is the natural fruit drop a few weeks after flowering, which is your signal to thin. The third is the first fruit reaching full size while still deep green, which is your signal to start the green picking. The fourth is the first frost in the forecast, which is your signal to protect or move. The fifth is unique to this crop: full orange color on the fruit you left hanging, which is your signal to start tasting.

Everything else fills in around those five. After two seasons you will know roughly how many weeks separate them in your own garden, and the calendar becomes something you anticipate rather than react to.

Two things stay fixed regardless of climate. Feeding goes on in spring and off at the end of summer, without exception, because late nitrogen produces soft wood and this is a subtropical tree with very little frost tolerance to spare. And protection comes before the frost, not on the night it is forecast, because a tree that must be moved is always heavier and more awkward than you remembered.

Spring: wake it up and set it up

Spring is the busiest part of the year, and most of the work happens before the tree looks like it is doing anything at all. Get the pruning, the repotting and the first feed done while it is still quiet and the rest of the season largely runs itself.

1. Prune before the buds swell Once the risk of cold has passed, take out suckers below the graft, dead and cold-damaged wood and crossing branches, then thin the congested interior until daylight comes through. Keep the total to a quarter of the canopy.
2. Repot or top-dress Every two to three years, move a container tree up one pot size, or refresh the top two inches (5 cm) of compost if it is already in its final pot. Do this before growth starts, not during it.
3. Start feeding at the first sign of growth Begin a citrus fertilizer as soon as the buds move: fortnightly for a potted tree, or a slow-release granular feed for one in the ground. Do not start before the tree does.
4. Move a wintered tree out gradually Once nights are reliably above freezing, put the pot out for a few hours a day for a week before leaving it out permanently. Leaves that spent the winter indoors scorch badly in unfiltered sun.
5. Increase watering as the flush expands Demand rises quickly once new leaves open. Move from a weekly check to every two or three days, and water until it runs freely from the base of the pot.

Summer: set the crop, thin it, carry it

Flowering runs from late spring into early summer and is heavily scented. Do not spray anything while the tree is in flower. If it is under cover for any reason at that point, get it outside so insects can reach the flowers, or the set will be poor.

The natural drop follows a few weeks later. Let it run its course completely, then thin what remains: crowded clusters back to two or three fruit, and back to one or two on any branch you intend to leave hanging for the late harvest. Remove anything already scarred and leave nothing touching its neighbor, because thin rind rubbed against thin rind marks both fruit. This is the single decision that most affects whether you get a crop again next year rather than a bare season.

Through mid and late summer the job is water and support. A potted tree carrying fruit may need daily water in heat, and swings between dry and saturated are what split this thin-skinned fruit. Tie up any branch bending under weight before it tears at the crotch, and rub out inward-facing new shoots with a gloved thumb as they appear. Then, at the very end of summer, stop feeding entirely.

Autumn: finish the green crop and prepare for cold

The green picking usually straddles the turn of the season. Keep going over the tree every four or five days, taking fruit that is full size and still deep green with a tight skin, and leaving what is still filling. The interior fruit finishes later than the outer fruit, sometimes by weeks, and repeated picking is how each fruit gets taken at its own peak.

Once the earliest fruit begins to lose its green, stop and decide. Everything you still want as a sharp juice crop should come off now, because nothing improves in that direction after this point. Whatever you have chosen to leave for the late harvest stays, on well-lit branches, thinned hard.

Then do the winter preparation before you need it. Reduce watering as growth slows, do not feed, do not prune, and clear fallen leaves and dropped fruit from the base, because that debris is where pests overwinter. Work out now where the pot is going and how it will get there, and have row cover to hand for a ground-planted tree. This tree is damaged by frost at temperatures other sour citrus tolerate, so a night that catches you unprepared costs real damage rather than a scare.

Winter: keep it alive, keep it dry, and finish the late crop

Cold is the limiting factor on this plant. A ground-planted tree in a nearly frost-free garden needs mulch over the root zone and row cover over the canopy whenever frost is forecast, taken off again on mild days so the leaves get light. Anywhere colder than that, the pot comes under cover before the first hard frost, not after it.

Indoors, what it wants is bright light and cool air, in that order. An unheated but frost-free porch, a conservatory or a bright cool room suits it far better than a warm living room, where heat and dry air together bring on spider mites and cause leaf drop. Keep it away from radiators and away from the draft of an opened door. Water sparingly: let the mix approach dryness before watering again, every ten to fourteen days or less, and never leave the pot standing in water, because cold wet compost kills more overwintering citrus than cold air does.

The late crop finishes during this period. Fruit left hanging colors to orange and then slowly sweetens over the following months. Taste one every couple of weeks rather than judging by color, because full color arrives well before full sweetness. Pick each branch when the sourness has softened to your liking. If the tree has to come indoors to a warm space, clear the fruit first at whatever stage it has reached, because it will go soft in the warmth. Check leaf undersides for scale and mites every fortnight while the tree is under cover.

Do not prune or feed a tree that is overwintering under cover, however untidy it looks. Both push soft growth that has no light to support it, and that growth is the first thing lost when the tree goes back outside in spring.

The dates worth recording every year

Keep one short note per year with six entries: the date the spring flush started, the date the natural fruit drop finished, the date you took the first green fruit, the date you finished the green picking, the date the held fruit colored fully, and the date you decided it was sweet enough to clear. Add the lowest temperature the tree actually saw over winter and the number of fruit taken in each of the two harvests.

Those figures are the entire calendar for your own garden. After two seasons the gaps between the events stop being guesswork, and you will know how many weeks after flowering to thin and roughly which week to start looking for full-sized green fruit. Add a line on what winter protection you gave and how much leaf drop or dieback showed the following spring, and within three years you will know exactly how much protection this tree needs in your position.