Gadenin日本語Get the appSite it for the thorns before you site it for the sun
Every other citrus is planted for light and shelter first. Yuzu has one extra constraint that overrides both, and people who ignore it spend the next twenty years regretting the position. The thorns are up to three inches (7 cm) long, needle straight, woody and set at the base of almost every leaf on young wood. They will go through a jacket sleeve, and they point in every direction including outward over a path.
Give it a clear yard (90 cm) of dead space on every side that a person, a hose or a wheelbarrow has to pass. Never plant it beside a doorway, a washing line, a garden tap, a compost bin or anywhere a child cuts a corner. If you are planting more than one, set them far enough apart that you can still get a wheelbarrow between the canopies at full size.
After that, treat it like any citrus: full sun, at least six hours, and shelter from the prevailing winter wind. A wall or fence facing the midday sun is ideal because the stored heat lifts the night minimum by several degrees, and in a cold garden those few degrees are the whole margin.
| Neighbor | Minimum clearance | Reason |
|---|---|---|
| Path or lawn edge | 3 ft (90 cm) | Branches sag under a fruit load and reach further than you expect |
| Wall or fence | 3 ft (90 cm) | You need to get behind it to prune and to row cover it |
| Another yuzu | 12 ft (3.6 m) | Access with a barrow between mature canopies |
| Doorway, tap, washing line | Do not plant there | Anywhere used in the dark or in a hurry is the wrong place |
| Overhead cable or eaves | 12 ft (3.6 m) headroom | It reaches 10-12 ft (3-3.6 m) and is unpleasant to reduce later |
Grafted or seedling: the difference is a decade
A grafted tree carries wood taken from an adult plant, so it is already past its juvenile phase and flowers within about three years of planting, sometimes in its second. A tree raised from a seed has to grow through juvenility itself, and that takes ten to eighteen years before the first flower. It is not a small difference and it is not something feeding or pruning can shorten.
Seedlings are also thornier and often larger, because juvenile wood carries the longest thorns. If someone offers you a yuzu grown from a pip, take it only as a curiosity or as future rootstock, never as your fruiting tree.
The rootstock matters as much as the top. Yuzu on a hardy rootstock with three-leaflet leaves is the combination that survives cold gardens; the same variety on a tender rootstock is not the hardy plant you were promised. Look at the swollen graft union near the base and remember the leaf shape below it, because you will need to recognize suckers from it for the rest of the tree's life.
| Type of plant | First flowers | Use it for |
|---|---|---|
| Grafted, 2-3 ft (60-90 cm) tall | 3rd year after planting | Your fruiting tree |
| Grafted, older and larger | 1st or 2nd year | A quicker crop, harder to establish |
| Seedling from a pip | 10-18 years | Rootstock or curiosity only |
| Rooted cutting | 4-6 years | Workable, usually less hardy at the root |
Plant high, plant into the native soil
The commonest way to kill a young yuzu in a cold garden is to plant it in a hole full of rich imported compost. The hole holds water like a bucket, the roots stay wet and cold through winter, and a plant that would have survived the air temperature dies at the root instead.
- Dig wide and shallow Make the hole three times the width of the rootball and no deeper than it. Loosen the sides with a fork so roots can leave. On heavy clay, mound the whole planting position six to eight inches (15-20 cm) above the surrounding grade before you start.
- Do not enrich the backfill Backfill with the soil you dug out, mixed with no more than about a fifth grit or coarse bark if the ground is heavy. Rich compost in the hole encourages roots to circle inside it rather than push out into the garden.
- Set the top of the rootball proud The surface of the rootball should sit one to two inches (3-5 cm) above the finished soil level. It will settle. A yuzu planted an inch too deep is slow for years and prone to collar rot.
- Keep the graft union well clear The swollen union must end up at least four inches (10 cm) above soil and above the eventual mulch line. Buried, it roots from the scion and you lose the hardiness the rootstock was giving you.
- Water in and mulch, leaving a collar Firm gently, water with about four gallons (15 liters), then mulch two to three inches (5-8 cm) deep over the root zone but pull it back to leave a hand's width of bare soil around the trunk.
Plant in early spring rather than autumn wherever winters are cold. A spring planting gets a full growing season to root out before its first hard frost, and that single season is often the difference between a tree that shrugs off winter and one that dies back to the graft.
The first three winters are not the same as the rest
An established yuzu with a mature trunk and a woody root system is by a wide margin the most cold hardy citrus worth growing for fruit, and takes temperatures well below freezing without protection. A newly planted one is not that plant yet. Hardiness in citrus is earned through wood maturity and root mass, and a two-foot whip in its first winter can be damaged at temperatures its parent would ignore.
For the first three winters, wrap the trunk and the lower framework in row cover before the first hard frost and pile eight inches (20 cm) of loose mulch over the root zone, again keeping it off the bark. Take the row cover off on mild days so the leaves get light, and remove it entirely once nights are reliably above freezing. From the fourth winter you can usually stop, and the tree will look after itself.
Stop feeding by late summer in all of those years. Nitrogen late in the season pushes a soft flush that does not harden before cold arrives, and that soft wood is what gets killed.
What to write down at planting
Record the planting date, whether the tree is grafted or a seedling, the rootstock if you know it, and the height at planting. Sketch or photograph the position of the graft union so you can tell a sucker from a real branch in three years when the base has thickened.
Then add one line each winter: the lowest temperature the tree saw, whether you fleeced it, and how much leaf or shoot damage showed the following spring. Three winters of that gives you your own hardiness figure for your own garden, which is worth far more than any published number, and tells you exactly when it is safe to stop wrapping.