Gadenin日本語Get the appThe four fixed points the year hangs on
Rather than dates, run the year off four events you can actually see, because they move with your climate and a calendar does not. The first is the spring flush, when the buds break and the tree pushes new leaves; that is the signal to start feeding. The second is the natural fruit drop a few weeks after flowering, which is the signal to thin. The third is the first fruit reaching full size while still deep green, which is the signal to start picking. The fourth is the first frost forecast, which is the signal to protect or move.
Everything else in the year is filled in around those four. Once you have watched a tree for two seasons you will know roughly how many weeks separate them in your garden, and the calendar becomes something you anticipate rather than react to.
The one thing that is fixed regardless of climate is the direction of feeding: on in spring, off by the end of summer. A sudachi is only moderately hardy, considerably tougher than a true lime but well short of a yuzu, and late nitrogen produces soft wood that a moderate freeze will kill.
Spring: wake it up
Spring is the busiest part of the year and most of it happens before the tree looks like it is doing anything. Get the pruning, the repotting and the first feed done while it is still quiet, and the season runs itself from there.
- Prune before the buds swell Once the hardest frosts have passed, take out suckers below the graft, dead and frost-damaged wood, and crossing or inward-facing branches. Keep the total to a quarter of the canopy or less.
- 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.
- 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 growth does.
- Move a wintered tree out gradually Once nights are reliably above freezing, put the pot outside for a few hours a day for a week before leaving it out. Leaves that spent winter indoors scorch in unfiltered sun.
- Increase watering as the flush expands Demand rises fast once new leaves open. Move from a weekly check to every two or three days, and start watering until it runs from the base of the pot.
Summer: set the crop and carry it
Flowering happens in late spring to early summer, and it is heavily scented. Do not spray anything while the tree is in flower. If it is in a pot indoors or under cover for any reason at that point, move 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, then thin what remains: take crowded clusters back to two or three fruit, remove anything already scarred, and leave nothing touching its neighbor. 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 the fruit. Tie up any branch bending under weight before it tears. Rub out inward-facing new shoots with a gloved thumb as they appear. Then, at the end of summer, stop feeding entirely.
| Stage of summer | Main job | Watch for |
|---|---|---|
| Flowering | Leave it alone, ensure insect access | No sprays of any kind while in flower |
| Just after flowering | Nothing; let the natural drop happen | Do not thin yet |
| Drop finished | Thin clusters to two or three fruit | Fruit touching, scarred or misshapen |
| Fruit swelling | Water steadily, support loaded branches | Splitting means the watering is uneven |
| End of summer | Last feed, then stop | Late nitrogen ruins winter hardiness |
Autumn: pick green, then wind down
Harvest is the whole of autumn's first half and it is the point of the year. Start picking as soon as the earliest fruit is full size while still deep green with a tight skin, and go over the tree every four or five days rather than stripping it in one session. The interior fruit finishes later than the outer fruit, and picking over the tree repeatedly is how each fruit gets taken at its own peak.
Clear the tree once the first fruit begins to lose its green. Nothing improves after that point, so there is no reason to leave anything hanging. A tree still carrying a load into cold weather also has less in reserve for the following spring.
After the harvest, ease off. Reduce watering as growth slows, do not feed, and do not prune. Clear fallen leaves and any dropped fruit from around the base, because that debris is where pests overwinter. Then get the winter arrangements ready before you need them, not on the night of the first frost warning.
Winter: keep it alive and keep it dry
Sudachi takes more cold than a true lime, so it is not a plant that needs a heated greenhouse, but it is well short of a yuzu and it will not sit outside through a hard freeze. Where winters are mild, a ground-planted tree needs mulch over the root zone and row cover over the canopy during cold snaps, removed on mild days so the leaves get light. Where winters are properly cold, the pot comes in.
Indoors, the requirements are bright light and cool air, in that order. An unheated but frost-free room, a porch or a conservatory suits it far better than a warm living room, where the combination of heat and dry air brings on spider mites and causes leaf drop. Keep it away from radiators and away from drafts from an opened door.
Water sparingly. Cold wet compost kills more overwintering citrus than cold air ever does. Let the mix approach dryness before watering again, every ten to fourteen days or less, and never leave the pot standing in water. Check the leaf undersides for scale and mites every couple of weeks while it is indoors, because that still warm air is exactly what they want and an unnoticed population will strip the tree by spring.
Do not prune or feed a tree that is under cover for winter, however untidy it looks. Both push soft growth that has no light to support it, and that growth is the first thing to be lost when the tree goes back outside in spring.
The four dates worth recording every year
Keep one short note per year with four entries: the date the spring flush started, the date the natural fruit drop finished, the date you picked the first fruit, and the date you cleared the tree. Add the lowest temperature the tree saw over winter and the total number of fruit you got.
Those six figures are the entire calendar for your own garden. After two seasons the gaps between them 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 you did about winter protection and how much damage showed the following spring, and within three years you know exactly how much protection your tree actually needs rather than how much a general guide suggests.