How to repot a plant UK — the 7-step British method

How to repot a plant UK — the 7-step British method

Repotting is one of those tasks that looks intimidating but is genuinely simple once you've done it once. The key principles for UK plant owners: don't go too big, don't damage roots unnecessarily, and don't repot a stressed plant. This guide is the universal method that works for around 95% of UK houseplants, with British-specific notes on compost brands, pot sizing conventions and timing.

Know when to repot: Add your plants to Growli — the app tracks how long each plant has been in its pot and suggests repotting season based on growth signals.

When to repot (and when NOT to)

Repot when:

• Roots circle the bottom of the pot (slide the plant out and look)
• Roots grow out of the drainage hole
• Water runs straight through the compost without absorbing
• Plant has been in the same pot for 2-3 years
• Compost has visibly compacted or smells off
• Plant has outgrown its container visually (top-heavy, falling over)

Don't repot when:

• Plant is actively flowering
• Plant is recently purchased or recently moved (let it acclimatise to your UK home for 2-4 weeks first)
• Plant is sick — diagnose and treat the underlying problem first (see why is my plant dying UK)
• It's UK autumn or winter (October-February — most plants are dormant; repotting stress is harder to recover from in cool British conditions)

Best time: Early UK spring (March-April), just as new growth starts. For tropical houseplants in temperate conditions, that's slightly later in the north (Scotland, northern England) than in the south.

UK pot sizing — don't go too big

The biggest beginner mistake. Go up just 2-3 cm in diameter from the current pot (about 1 inch). Larger pots hold too much compost for the existing root mass and cause root rot — a particular hazard in cool damp UK rooms where compost stays wet for longer than in American homes.

Example: a plant in a 12 cm pot goes into a 14 or 15 cm pot, not a 25 cm pot.

For mature plants whose root mass is sized to the pot: same size or only 1 cm up.

UK pot conventions

Pot sizing in the UK differs from US conventions:

• Indoor / houseplant pots: Measured by diameter at the top in centimetres. Common UK sizes: 9 cm (small starter), 12 cm, 14 cm, 17 cm, 20 cm, 24 cm, 30 cm.
• Outdoor / garden pots and shrubs: Measured by volume in litres. Common UK sizes: 1 L, 2 L, 3 L, 5 L, 7.5 L, 10 L, 15 L, 25 L, 50 L.
• Conversion rule of thumb: A 12 cm round plastic pot holds roughly 1 litre of compost. A 17 cm holds roughly 2.5 litres. A 24 cm holds roughly 7-8 litres.
• The "P9" or "9 cm pot" is the standard small UK starter pot — most houseplants ship in this size from nurseries.

UK retailers (B&Q, Wickes, Homebase, Dobbies, Notcutts, Crocus, RHS Plants, IKEA UK) all use the centimetre convention for houseplant pots and the litre convention for outdoor/garden pots.

Choose the right pot

Three considerations:

1. Drainage hole — non-negotiable. Decorative cachepots without drainage cause overwatering, particularly in cool UK rooms.
2. Material — terracotta absorbs excess moisture (good for UK overwaterers and damp British rooms); plastic retains more (good for forgetful waterers); glazed ceramic is between.
3. Shape — round and tall for trailing/tall plants; round and wide for surface-rooting plants (succulents).

UK terracotta pots from local potteries (Whichford Pottery, Yorkshire Flowerpots) wick moisture exceptionally well and suit overwaterers; cheap imported terracotta and plastic pots from B&Q or The Range are perfectly adequate for most houseplants. Glazed ceramic is the most decorative and the slowest-drying — best for plants that like consistent moisture (peace lily, prayer plant).

Compost — match to plant (UK brands)

Standard peat-free houseplant compost works for 80% of UK houseplants. The exceptions:

• Cacti and succulents — gritty mineral mix (50% perlite or horticultural grit added to standard mix). Westland Cacti & Succulent Compost is widely stocked.
• Orchids — bark-based orchid mix, NOT regular potting compost. Westland Orchid Compost or similar.
• Aroids (monstera, pothos, philodendron) — chunky aroid mix: orchid bark + perlite + coco coir + worm castings. Mix your own from Westland Orchid Compost + perlite + Sylvagrow Houseplant.
• African violets — light peat-free African violet mix or Sylvagrow Houseplant with extra perlite.
• Ferns — moisture-retentive mix with extra coco coir.

UK compost brands (verified live 2026)

• Westland Peat-Free Houseplant Potting Mix — widely stocked at B&Q, British Garden Centres, Wickes. £6-12 for 10 L. Enriched with Seramis granules and perlite.
• Sylvagrow Houseplant (Melcourt) — RHS-approved peat-free houseplant compost. Premium quality, blend of bark, wood fibre and coir. £8-15 for 15 L. Stocked at Mr Fothergill's, Dobbies, RHS Plants.
• Miracle-Gro Premium Indoor Plant Compost — supermarket and B&Q availability.
• Westland Cacti & Succulent Compost — for jade, aloe, echeveria, haworthia.

The RHS has officially recommended peat-free compost since the UK peat ban for retail sale (which came into force progressively from 2024-2026). Don't reuse old compost — it's depleted, may carry pathogens, and is often compacted.

The 7-step UK method

Step 1 — Water the day before

Water the plant the day before repotting. Moist compost releases from the pot easily and roots are less brittle. Dry compost makes the root ball crumble.

Step 2 — Prepare the new pot

Place a small piece of mesh or a coffee filter over the drainage hole to prevent compost falling out (optional — bigger drainage holes don't need it). Fill the pot 1/4 to 1/3 full with fresh peat-free compost. No "drainage layer" of pebbles needed — that's a myth that actually impedes drainage, confirmed by RHS guidance.

Step 3 — Remove the plant from the old pot

Squeeze the sides of plastic pots to loosen, or gently tap a terracotta pot's rim. Turn upside down with one hand supporting the compost surface around the stem. Wiggle and pull gently.

If stuck, slide a butter knife around the inside edge of the pot, then try again.

Step 4 — Inspect the roots

A healthy root ball is white or pale tan, with roots filling the compost mass. Three problems to fix:

• Circling roots: Gently loosen the outer roots with your fingers. Severe root-binding may need vertical cuts down the side of the root ball with clean scissors.
• Dead black roots: Cut off with clean scissors. RHS guidance: "Prune away all decayed roots until only firm, white healthy tissue remains."
• Old compacted compost: Loosen and remove some, but don't disturb a healthy root ball more than necessary.

Step 5 — Position the plant

Place the plant in the new pot so the top of the root ball sits 2-3 cm below the pot rim (to leave space for watering). Adjust the compost base depth up or down as needed.

Step 6 — Fill in with fresh compost

Add peat-free compost around the root ball. Tap the pot gently on the work surface to settle the compost into gaps. Don't pack it tight — you want air pockets for roots to breathe.

Leave the top of the root ball just below the compost line. Don't bury the stem deeper than it was before (except for tomatoes, which actively grow new roots from the stem).

Step 7 — Water lightly

Water lightly to settle the compost. Don't soak — the disturbed roots need a few days to heal before facing wet conditions. Resume normal watering schedule after 5-7 days.

Post-repotting care (first 2 weeks)

• No fertiliser for 4-6 weeks. Fresh peat-free compost has nutrients sufficient for the first 4-6 weeks; feeding now stresses roots. RHS guidance aligns.
• No direct sun for 1 week. Move to bright indirect light to reduce transpiration stress. Particularly important during a UK summer heatwave.
• Some leaf drop is normal — the plant is acclimatising. Don't panic at 1-3 leaves.
• Check compost moisture daily for the first week — repotted plants can dry out faster initially.

If multiple leaves drop in week 1, the plant is in transplant shock. Keep humidity slightly higher (cluster pots together or run a small humidifier), water lightly and wait. Recovery is usually within 2-3 weeks.

UK seasonal repotting calendar

Related articles

• Snake plant care UK — the bulletproof British houseplant — snake-plant-specific repotting
• Monstera care UK — Swiss cheese plant complete guide — aroid mix repotting
• Calathea care UK — fix the humidity or skip the plant — fussy repot timing
• How often to water succulents UK — the watering and compost basics
• Why are my plant leaves turning yellow? UK guide — if repotting stresses your plant
• Indoor plants for beginners UK — broader houseplant context for first-timers
• Best house plants UK — for British homes 2026 — when you're ready for plant #2

Reviewed and updated by the Growli editorial team. For questions about anything here, open Growli and ask — or email hello@getgrowli.app.