Gadenin日本語Get the appDecide the winter plan before you decide the hole
A lime is damaged at temperatures a lemon shrugs off. Leaves burn in the low 30sF (around 0C) and wood is killed in the high 20sF (about minus 2C), where a mature lemon will sit through the same night and only drop a few leaves. That single fact should drive the planting decision rather than any question of soil or spacing.
If your winter lows stay above the mid 30sF (about 2C) you can plant in open ground. If they touch freezing at all, plant into a large pot from the start and accept that the tree lives outdoors from spring to autumn and under cover for the cold months. Planting in the ground and hoping to row cover it every year is the route most people regret, because the night that catches you out is always the one you were away for.
| Winter low | Where to plant | What to expect |
|---|---|---|
| Above 40F (4C) | Open ground | Growth and fruiting almost year round |
| 35-40F (2-4C) | Open ground, sheltered wall | Slower winter, occasional leaf marking |
| 30-35F (minus 1 to 2C) | Large pot, moved under cover | Fine if the move happens before the first cold snap |
| Below 30F (minus 1C) | Pot only, indoors for winter | Unprotected wood is killed outright |
Pot size, and why bigger is not better
Size the pot by what you can move on your own, not by the tree. A pot you cannot shift alone is a pot that stays out through a frost. A young lime with a rootball around eight inches (20 cm) across goes into a 12 to 14 inch (30-35 cm) pot. Step up two to four inches (5-10 cm) of diameter every second or third year until you reach a working ceiling of about 20 inches (50 cm), then hold it there and root prune instead of going larger.
Put the empty pot on a wheeled caddy before you fill it. A 20 inch pot with wet mix and a tree in it runs past 90 pounds (40 kg), and you will not slide a caddy under it afterwards without a second person. Plastic and glazed pots hold water longer than terracotta, which helps through summer heat and works against you in a cool winter room.
Do not over-pot a small tree in the hope of skipping a step. A large volume of mix around a small root system stays wet for days, and a lime with cold wet roots sheds leaves within two weeks.
A gritty mix that drains in seconds
Limes tolerate poor soil far better than they tolerate airless roots. A standard all-purpose potting mix, watered by a careful person, becomes a wet sponge by midwinter. Cut it hard with grit so that water runs straight through.
Aim for roughly two parts good potting mix, one part composted bark or coir, and one part coarse grit or perlite around a quarter of an inch (5 mm). Add a slow release citrus feed at the label rate. Skip the old advice about crocks in the base, which raises the saturated layer rather than lowering it. A single square of mesh over the drainage hole is all you need.
In open ground, do not dig a deep pit and backfill with rich compost. That makes a sump. Loosen a wide shallow area, about three times the rootball across and no deeper than the rootball itself, and plant into the native soil with grit worked into the top few inches.
Setting the tree in
Almost every lime you buy is grafted, and the swollen union sits two to six inches (5-15 cm) above the roots. Keep it clearly in the air. Buried, it rots, and the scion roots over the top of the rootstock, which throws away the rootstock's vigor and whatever cold tolerance it brought.
- Part fill and sight the height Add mix until the rootball shoulder will finish about an inch (2.5 cm) below the pot rim, and about half an inch (1 cm) proud of the finished compost level. Sit the tree in and check by eye across the rim before any backfilling.
- Deal with circling roots Do not tease the rootball apart out of habit. If roots circle the outside, make three vertical cuts an inch (2.5 cm) deep down the sides with a clean knife and leave the rest intact.
- Backfill in thirds Add mix a third at a time and tap the pot on the ground between each addition. Do not press with your thumbs. Compacting a gritty mix undoes the drainage you just built.
- Water twice Water slowly until it runs from the base, wait ten minutes, then water again. The second watering wets the dry pockets the first one ran straight past.
- Stake only if it rocks A trunk that rocks in wind tears its new roots. Use one short cane tied low and remove it after a season. A tall rigid stake produces a weak trunk that cannot stand alone.
- Hold off feeding for a month The slow release in the mix is enough. Liquid feed on a freshly potted tree pushes soft growth before the roots can carry it, and soft growth is exactly what leafminer and scale go for.
Where it stands, and what to write down
Give the sunniest position you have with at least six hours of direct sun, and shelter from wind. Wind is the underrated problem with a potted lime: it dries the mix faster than sun does, and it scrapes young fruit against the thorns until the skin is scarred for good. A wall that holds warmth into the evening buys real degrees on a cold night.
Write down the planting date, the pot diameter, and the compass direction the tree faces. Add the date of the first cold night that made you move it under cover. Two seasons of those notes tell you your own move date far better than any general rule, and they also tell you when the pot is due to step up.