How and when do I repot a houseplant?
The signs a plant needs repotting, choosing the right pot size, and the aftercare that prevents transplant shock.
- Difficulty
- beginner
- Time
- 30 min
- Read
- 2 min
Short answer
Repot when roots come out of the drainage holes or water runs straight through, going up just one pot size. A pot much larger than the rootball holds wet compost the roots cannot reach, which causes rot.
Repotting into too large a pot is the most common mistake, and it kills plants by keeping the compost wet. Going up one size at a time keeps the root-to-compost ratio right and the plant grows into it.
What you'll need
- A pot one size larger
- Fresh compost
- Newspaper or a sheet (optional)
- Watering can (optional)
Step by step
- Check whether it actually needs repotting.Roots emerging from drainage holes, water running straight through, or growth slowing despite feeding. Repotting a plant that does not need it causes unnecessary stress.
- Go up only one pot size.About 2-5cm wider in diameter. A much larger pot holds wet compost beyond the roots' reach, which stays saturated and causes root rot.
- Repot in spring where possible.At the start of active growth, so the plant establishes quickly. Repotting a dormant plant in winter is more stressful and slower to recover from.
- Water the plant the day before.It makes removal easier and reduces the shock. A bone-dry rootball breaks apart when handled.
- Ease the plant out rather than pulling the stem.Squeeze the pot, tip it and support the base of the plant. Pulling by the stem damages it and can separate it from the roots.
- Loosen circling roots.Gently tease out any that have wound round the rootball. Left circling, they continue to do so and eventually strangle the plant.
- Plant at the same depth in fresh compost.Not deeper. Burying the stem causes rot. Firm gently and leave a gap below the rim for watering.
- Water in and then leave it alone.Water thoroughly once, then hold off feeding for six weeks — fresh compost contains nutrients and the roots need time to recover.
Tips
- Some plants flower better when slightly pot-bound and should be left. Check the species rather than repotting everything on a schedule.
- Top-dressing — replacing the top few centimetres of compost — is a good alternative for large plants that cannot be repotted easily.
- Terracotta pots dry out much faster than plastic. That suits plants prone to overwatering and is a problem for thirsty ones.
Common mistakes
- Repotting into a much larger pot — The compost beyond the roots stays saturated, which causes root rot. One size up at a time is the rule.
- Planting deeper than before — Burying the stem causes rot at the base. The plant should sit at exactly the same depth as it was.
- Feeding immediately after repotting — Fresh compost already contains nutrients and damaged roots are easily burnt. Wait about six weeks.
Questions people ask
How do I know when a plant needs repotting?
Roots growing out of the drainage holes, water running straight through without being absorbed, or growth slowing despite adequate light and feeding.
How much bigger should the new pot be?
Only one size — about 2-5cm wider in diameter. A much larger pot holds wet compost the roots cannot reach, which stays saturated and rots them.