Gadenin日本語Get the appThe four decisions that shape the year
Most of what a satsuma needs is steady and undramatic: water, a little food, mulch kept off the trunk. But four jobs have narrow windows, and missing any of them costs you a season. Prune in late winter before the flush breaks, or you cut off the flowers. Protect the tree through the coldest nights and the bloom, or there is nothing to thin. Thin the fruit in early summer, or you set up the alternate bearing swing. Clear the tree at harvest, or you suppress next year's flowers and lose the fruit to puffiness.
Everything else is adjustable; if you feed a fortnight late, nothing much happens. Treat the four hinges as fixed points and let the rest float around them. The stages below are written as signals rather than dates, because a satsuma's year runs on temperature: bud swell, petal fall, the end of natural fruit drop and the loosening of the skin are the markers that tell you where you are.
| Stage | What the tree is doing | Your job | The signal to act |
|---|---|---|---|
| Late winter | Dormant, buds beginning to swell | Prune, check the graft height, mulch | Hard freeze risk has passed |
| Early spring | First flush, then flower buds | First nitrogen feed, keep water even | New shoots emerging at the tips |
| Bloom | Flowering, then petal fall | Do not spray, do not let it dry out | Petals on the ground |
| Early summer | Natural fruit drop, then sizing | Thin hard, second light feed | Fruit drop has stopped for a week |
| Midsummer | Fruit sizing, bud formation for next year | Water evenly, hold nitrogen steady | Fruit reaching golf ball size |
| Late summer | Fruit filling, skin still green | Stop nitrogen, keep water constant | Growth slowing, no new flush wanted |
| Autumn | Color developing, sugar rising | Weekly taste test, no feeding | Skin beginning to turn on the sunny side |
| Harvest | Fruit at eating quality | Clip in stages, clear the tree | Skin loosening, fruit sweet |
| Early winter | Resting, hardening off | Mulch, prepare frost protection | Nights turning consistently cold |
Water and feed: steady beats generous
Satsumas want even moisture and hate both extremes. A tree that swings between bone dry and soaked drops flowers, drops small fruit, splits ripening fruit and forms fewer buds for the following year. The most valuable thing you can do for fruit quality is hold the moisture steady through summer, and the easiest way is a mulch two to three inches (5-8 cm) deep, spread to the canopy edge and kept four inches (10 cm) clear of the trunk.
In warm weather a mature tree in the ground wants a deep soak roughly every seven to ten days rather than a daily sprinkle. Wet the top eighteen inches (45 cm) of soil, where almost all the feeding roots are, then let the surface dry before the next soak. Check by pushing a probe or a finger down four inches (10 cm); if it is damp there, wait.
Feed nitrogen in two or three light applications spread across the first half of the growing season rather than one large one. The last feed should go on early enough that no soft growth is being pushed into late season, because that growth attracts leafminer and will not harden before cold weather. Citrus is also prone to iron, zinc and magnesium shortages on alkaline soils, which show as pale leaves with green veins; those respond to a foliar micronutrient feed on the new flush, not to more nitrogen. And check soil moisture before reaching for the feed at all: yellow leaves on a satsuma are more often waterlogged roots than hunger, and feeding a tree whose roots are drowning only accelerates the decline.
Cold weather: the satsuma advantage and its limits
A satsuma is the hardiest sweet citrus in ordinary cultivation. A mature, unstressed tree comes through brief dips into the low twenties Fahrenheit (around minus 5C) with only leaf bronzing, well beyond what a lemon or lime tolerates. That is why satsumas are grown outdoors where no other sweet citrus survives.
The margin has conditions attached. It applies to mature trees, not to one in its first two winters; to trees hardened off rather than pushing soft late growth; and to short overnight dips rather than a cold spell lasting days. Hanging fruit is more tender than the wood and damages several degrees above the point at which the tree is hurt, so a freeze during ripening can cost the crop while leaving the tree untouched.
Preparation starts in late summer, not on the night of the frost. Stop nitrogen early so growth hardens off, keep the tree watered going into cold weather because moist soil holds and releases heat better than dry soil, and wrap the trunk of a young tree from the ground up past the graft union; even if the top is killed, a protected graft regrows as itself rather than as rootstock. On a forecast freeze night, water the ground thoroughly during the day, then drape the whole canopy with frost cloth taken all the way to the ground so that soil heat is trapped underneath. Do not use plastic sheeting directly on the foliage; wherever it touches, it conducts cold straight to the leaf. Remove the covering during the day so the tree gets light and does not cook under a sunny sky.
Do not prune out cold-damaged wood in winter. Wait until growth has restarted in spring and you can see clearly where live tissue begins, then cut back to it. Cutting early almost always means removing wood that would have recovered, and it exposes fresh wounds to the rest of the cold season.
A short seasonal checklist
The list below is the whole year condensed to the actions that matter. Read it as a set of triggers rather than dates, and note against each one what the tree was actually doing when you did it.
- Late winter, before bud break Prune dead wood, crossing branches and water shoots. Scrape the soil back and confirm the graft union is still clear. Refresh mulch out to the canopy edge, keeping a bare ring around the trunk.
- Early spring, at first flush Apply the first light nitrogen feed as new shoots appear. Start regular watering as the weather warms, and check the base of the trunk for rootstock suckers, rubbing off any you find.
- Through bloom Keep water even; a dry spell during flowering drops flowers outright. Do not spray anything while the tree is in bloom. No pollination partner is needed, so there is nothing to do except leave it alone.
- Early summer, after natural fruit drop Thin the crop hard, removing half to two-thirds of the fruit on a heavy set. Break up clusters, remove the scarred and the shaded, and give a second light feed once the thinning is done.
- Midsummer to late summer Hold moisture steady through fruit sizing, which is when uneven watering causes later splitting. Stop nitrogen so no soft flush is pushed into the leafminer season and into autumn.
- Autumn, as color comes Taste one fruit from the sunniest part of the tree each week. Ignore skin color as a ripeness guide. Keep watering steady, because a dry-to-wet swing at this stage splits fruit.
- Harvest, in two or three passes Clip fruit with snips, trimming the stem flush to the button, and take the sunniest fruit first. Clear the tree completely, including small interior fruit, to avoid suppressing next year's flowers.
- Early winter Water the ground before a forecast freeze, have frost cloth ready to reach the ground, and wrap the trunk of any tree under three years old to protect the graft union.
The record that pays for itself
Keep one page per year with six lines on it: the date you pruned and how much you took, the date the flowers fell, the date natural fruit drop finished, the date and severity of thinning, the date of the first sweet taste test, and the date you cleared the tree. Add the rough fruit count and a note on the coldest night and any damage it caused.
Two years of that turns satsuma growing from guesswork into scheduling. The dates repeat within a week or two in a given garden, so you catch the two windows that actually matter, thinning and harvest, at the right moment. The fruit count in particular tells you the following spring whether you are heading into a heavy year and need to be ready to thin hard.