There's a habit worth breaking: buying a plant, getting it home, and repotting it that same afternoon. It feels like a kindness. Usually it's a setback. A plant that's just been through a shop, a van and your hallway is already coping with new light and new humidity. Disturbing its roots on top of all that is one stress too many.
Repotting is a genuinely useful thing to do at the right moment. It's also one of the easiest ways to waste compost, spend money you didn't need to, and quietly kill a plant with kindness. Here's how to tell the difference.
01The real signs a plant needs repotting
Not sure? Slide the plant out and look at the root ball — that's the honest test. These are the signs that actually mean "time for a bigger pot":
- Roots are growing out through the drainage holes, or circling round on the surface of the compost.
- The root ball is a solid mass of roots with barely any compost left to see.
- Water runs straight through and out the bottom without soaking in.
- It dries out within a day of watering, however much you give it.
- The plant is top-heavy and keeps toppling, or is badly slumped and rootbound.
If you're seeing several of these, repot. If you're seeing none of them, don't.
02When to leave well alone
A plant that's happy doesn't need a bigger pot. Growth, healthy leaves and roots that haven't run out of room are all reasons to stay put for another year.
Plenty of houseplants actively prefer being snug. Snake plants are the classic example — they do better slightly pot-bound and are more likely to flower when their roots are cosy. Repotting one "to be kind" often just gives you a bigger pot of wet compost.
And leave stressed plants alone: anything sick, recently bought, or sulking after a move needs to settle first. Let it find its feet for a few weeks, then reassess.
03The mistake almost everyone makes: potting up too big
When people do repot, they nearly always go too large — a little plant lands in an enormous pot "so it won't need doing again." This is the fastest route to root rot.
A small root ball can only drink from the compost it's actually touching. The rest sits soaking wet, with no roots to use it, and stays that way for days. Roots sitting in cold, airless, sodden compost rot. So go just one size up — roughly 2–3cm wider than the current pot. The RHS puts the ceiling at no more than a third larger. Small step, every time.
04How to do it properly
- Do it in spring or early summer, as growth resumes — not in autumn or winter.
- Water the plant an hour or two beforehand; a moist root ball slides out cleanly.
- Ease the plant out and gently tease a few circling roots loose so they grow outward.
- Use fresh peat-free houseplant compost.
- Sit the plant at the same depth — don't bury the crown or stem deeper than it was.
- Backfill and firm lightly. Don't compact it hard; roots need air.
- Water in well, then hold off feeding for a few weeks — fresh compost has enough to be going on with.
How we checked this
Every care and safety claim on this page is verified against horticultural and veterinary sources.
Sources: RHS — How to repot a plant · The Garden Professors — container planting: intuition vs. reality
Checked 29 July 2026. If our advice ever conflicts with the RHS, believe them and tell us.