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Ivy is vigorous below ground and a plant that looks unchanged above can be solidly root bound. The usual sign is not a dramatic one: the pot simply starts drying out within a day or two of watering, and the leaves get smaller each season.
Most plants want moving up every second spring. A young plant growing hard may need it every year, and an old one in a big pot may go three or four years with nothing more than a top dressing.
| What you notice | Meaning | Action |
|---|---|---|
| Dries out within a day or two | Roots have filled the pot | Repot in spring, one size up |
| Roots circling out of the drainage holes | Well past due | Repot now, teasing out the circling roots |
| New leaves smaller than old ones | Root bound, or short of light | Check the roots before you move the plant |
| White crust on the compost surface | Salt build up from feeding and hard water | Scrape it off and replace the top two inches |
| Water sits on top and drains slowly | The compost has collapsed | Repot into fresh mix, same size pot is fine |
Timing and pot size
Repot in spring, as growth restarts and the plant can put roots into the new compost straight away. Autumn is a workable second choice in a mild climate; midwinter is not, because the roots sit in wet unused compost for months.
Go up one size only, about an inch (2 to 3 cm) more diameter. The temptation with a vigorous plant is to jump two or three sizes and save yourself a job, but the unused compost around the rootball stays wet and that is where rot starts. Ivy also looks better slightly tight than swimming in a large pot.
Any free draining mix suits it. A standard peat free potting mix with a third by volume of perlite, grit or bark is right. Ivy is not fussy about the mix, but it will not tolerate one that stays saturated.
A wide, shallow pot suits trailing ivy better than a deep one. The roots are not deep, and a deep pot holds a reservoir of wet compost below them that never gets used.
Doing it
The whole job takes ten minutes. The two steps people skip are teasing out the roots and cutting the top back, and those are the two that decide how the plant looks a season later.
- Water the day before A moist rootball holds together and slides out cleanly. Repotting bone dry compost tears roots and the plant sulks for weeks afterwards.
- Ease the plant out and look at the roots Healthy ivy roots are pale and firm. Anything black, soft or smelling sour is rot: cut it away completely and use fresh compost, not the old mix.
- Tease out the base Loosen the bottom third of the rootball and pull the circling roots free. Left wound around, they carry on circling in the new pot and the plant never establishes properly.
- Set it at the same depth The old compost surface should sit at the same level in the new pot, half an inch below the rim. Burying stems deeper invites rot at the base.
- Fill, firm and water through Work fresh mix down the sides with your fingers rather than packing it hard, then water until it runs from the drainage holes and empty the saucer.
- Cut the top back Shorten the longest trails by a third at the same time. It balances the disturbed roots against the foliage, and the plant responds by branching from lower down instead of getting leggier.
The first month afterwards
Keep the plant out of direct sun and slightly cooler than usual for two or three weeks, and water only when the surface has dried. Fresh compost holds more water than the old rootball did, and the commonest post repotting failure is keeping it too wet while the roots are damaged.
Do not feed for six to eight weeks. New compost carries enough nutrient for that long, and feeding damaged roots does nothing useful. Some leaf drop in the first fortnight is normal; new growth at the tips is the signal that the plant has taken hold.
Note the date and the pot size each time you repot, along with what the roots looked like. Two entries is enough to tell you whether this plant is on a one year or a three year cycle, and you stop guessing.
When not to repot at all
A large established ivy in a heavy pot does not need moving simply because time has passed. Instead, scrape off and replace the top two inches (5 cm) of compost each spring, which removes accumulated salts and gives fresh nutrient without disturbing anything.
Equally, do not repot a plant that is struggling with spider mites or root rot as a way of fixing it. Deal with the actual problem first. A sick plant that is also recovering from root disturbance has two things to survive instead of one.