Gadenin日本語Get the appWhere the fruit actually comes from
Satsuma mandarins flower on growth made the previous season, mostly on short shoots near the outer surface of the canopy where light reaches. This one fact governs every pruning decision you will make. If you go over the tree shortening every shoot tip the way you might shear a hedge, you are cutting off precisely the wood that was going to flower, and the tree responds with a dense skirt of leafy regrowth that shades the interior and flowers even less the following year.
The productive alternative is to take out whole branches at their origin and leave the remaining branches full length. A satsuma left unpruned does not stop fruiting, it simply becomes a shell: a green outer layer two feet (60 cm) thick with a dark, twiggy, unproductive interior. Your job is to keep light and air moving into that interior so fruiting wood survives further in, and to keep the tree at a height you can actually harvest from.
Satsumas are naturally spreading and often droop under a heavy crop, so they need less structural intervention than an upright citrus. Most years, a mature tree needs nothing more than the removal of dead wood, crossing branches, low skirts and any shoot that has grown straight up through the middle.
When to cut
The window is after the coldest part of winter has passed and before the spring flush of new growth begins. Cutting earlier leaves fresh wounds exposed through the cold spells that are most likely to damage the tree; cutting later removes flower buds that have already formed and wastes energy the tree has already spent. In practice, prune once the risk of a hard freeze has gone and the buds are just beginning to swell.
You can remove obviously dead or broken wood at any time of year, and a single misplaced water shoot can come off whenever you notice it. What should not happen outside the window is general shaping, because summer and autumn cuts push soft new growth that has no time to harden before cold weather.
Keep the total taken in one year modest. Removing more than about a fifth of the living canopy triggers a strong vegetative response, and the tree spends the next season making leaves instead of fruit. If a neglected tree needs more than that, spread the work over two or three winters.
| Growth to remove | How to identify it | Cut it back to |
|---|---|---|
| Dead and broken wood | Gray, brittle, no green under the bark | Live wood or the branch collar |
| Rootstock suckers | Below the graft, often thorny, different leaf | Flush with the trunk, as soon as seen |
| Water shoots | Vertical, thick, unbranched, shoots through the top | Their point of origin, not shortened |
| Crossing branches | Two branches rubbing, bark worn shiny | Remove the weaker of the pair entirely |
| Low skirt | Branches that touch the ground under fruit load | Raise to about a foot (30 cm) of clearance |
| Dense interior twigs | Thin shaded wood that never bears | Thin selectively; do not strip the inside bare |
Removing suckers is the one job that cannot wait
Rootstock suckers come from below the graft union and belong to a different plant. They are usually more vigorous than the mandarin above, often carry thorns, and have a leaf that looks subtly wrong in shape or gloss once you know to compare. Left alone, a sucker draws away the vigor that should be going into the fruiting canopy, and a large one can eventually dominate the tree and leave you with a vigorous thorny thing that never produces edible fruit.
Check the base of the trunk every few weeks through the growing season, not just at pruning time. Rub a sucker off with your thumb while it is soft and green and there is nothing left behind; let it become woody and you have to cut it, and a cut stub often produces two or three replacements. Cut flush with the trunk, without leaving a stump.
The same walk is a good moment to look for growth on the trunk between the graft and the first scaffold branch. Those shoots are mandarin wood and not suckers, but they still take light and energy from the canopy and grow into badly placed branches. Remove them while they are small.
- Start with the dead wood Walk the tree and remove everything dead, broken or diseased first. Clearing that out changes what you can see and often reveals that half the crossing and rubbing problems you were worried about have solved themselves.
- Open the top for light Take out vertical water shoots at their base and thin any place where three branches leave the same point. Aim for a canopy that lets patchy sunlight reach the interior, not one you can see straight through.
- Raise the skirt Remove branches that will sit on the soil once they are loaded with fruit. Fruit touching the ground rots and invites soil-dwelling pests up into the canopy, and a clear skirt makes mulching, feeding and inspection possible.
- Bring the height down over years If the tree has grown taller than you can pick from, lower it by removing whole tall branches back to a lower side branch rather than by cutting the top off level. A flat-topped cut produces a thicket of vertical regrowth.
- Cut at the collar, and leave it alone Cut just outside the raised ring where a branch meets its parent, without slicing into the ring itself and without leaving a stub. Do not paint or seal the wound; citrus compartmentalises clean cuts perfectly well on its own.
Newly exposed bark sunburns. If you have opened the canopy enough to leave large limbs in full sun, paint those limbs with white water-based paint diluted about half with water. It looks odd for a season and prevents the bark splitting that follows a hot summer.
Record what you took and what it did
Write down the date you pruned, roughly how much of the canopy you removed, and which branches went. The following season, note whether the tree responded with fruit or with a surge of leafy growth. Two or three years of that record tell you far more about how much your particular tree tolerates than any general rule can, because vigor depends on the rootstock, the soil and how much nitrogen you feed.
It is also worth noting where suckers keep appearing. A trunk that produces suckers from the same point year after year usually has a wound or a buried section at that spot, and the note points you at the cause instead of leaving you dealing with the symptom every spring.