How to Repot a Houseplant: When, What Size, and the Right Mix

Repotting is routine maintenance that is easy to get wrong in one specific way: choosing a pot that is far too big. That single decision causes more plant deaths than almost any other well-intentioned intervention.

When a plant actually needs it

Signs that it is time:

• Roots growing out of the drainage holes or circling visibly on the soil surface
• Water runs straight through the pot within seconds without soaking in
• The plant needs watering every day or two — there is barely any soil left
• Growth has stalled despite good light and feeding
• The soil has broken down into dense, compacted material that no longer drains
• The pot is deforming or the plant keeps toppling over

Signs that it does not need it:

• It has been in the same pot for a while but is growing well
• You bought a nicer pot
• The plant has a problem you have not diagnosed yet

That last one matters. Repotting a struggling plant without knowing why it is struggling adds transplant shock to whatever was already wrong. Diagnose first — if the issue is overwatering or light, repotting will not help.

Pot size: the critical decision

Go up one size only — 1 to 2 inches wider in diameter.

The reasoning is straightforward. Roots absorb water from the soil around them. Soil with no roots in it has nothing drawing moisture out, so it stays saturated for weeks after watering. A small plant in a large pot is surrounded by a permanently wet reservoir, and root rot follows.

A slightly snug pot is genuinely healthier. Several plants — spider plants, peace lilies, orchids and snake plants among them — flower better when a little root-bound.

Choosing a pot

Drainage holes are non-negotiable. No technique compensates for their absence. A layer of gravel at the bottom does not create drainage; it just raises the waterlogged zone.

If you want a decorative pot with no hole, keep the plant in a plastic nursery pot that sits inside it, and lift it out to water and drain.

Material:

Material	Behaviour	Best for
Terracotta	Porous, dries fast	Succulents, cacti, snake plants, anything rot-prone
Glazed ceramic	Holds moisture, heavy and stable	Tropicals, thirsty plants, tall top-heavy plants
Plastic	Holds moisture, light, cheap	Nursery pots inside cachepots

Choosing the mix

Bagged potting soil straight from the bag is too dense for most houseplants. Adjust it:

Aroids (monstera, pothos, philodendron): 40% potting mix, 30% orchid bark, 20% perlite, 10% coco coir.

Succulents and cacti: cactus mix with 30–50% extra pumice, perlite or coarse grit. It should crumble apart when squeezed damp.

Ferns, calatheas, peace lilies: potting mix with 20% perlite. These want moisture retention with some aeration.

Orchids: coarse bark only, never soil. They are epiphytes and soil suffocates them.

Most other houseplants: potting mix with 20–30% perlite.

The method

A day or two before: water thoroughly. A hydrated root ball comes out intact; a dry one shatters.

1. Prepare the new pot. Add enough fresh mix to the bottom that the plant will sit at the same depth it did before — the soil line should end up in the same place on the stem.

2. Remove the plant. Tip the pot sideways, support the stem base between your fingers, and slide it out. If it resists, squeeze a plastic pot to loosen it or run a knife around the inside edge. Never pull by the stem.

3. Inspect the roots. Healthy roots are firm and pale. Trim any brown, soft or mushy ones with clean scissors, and remove dead material.

4. Loosen circling roots. If roots have wound around the outside of the root ball, tease them apart with your fingers, or make three or four shallow vertical cuts down the sides. Left alone, they keep growing in a spiral and eventually strangle the plant.

5. Position and fill. Set the plant centrally and add mix around the sides, tapping the pot to settle it. Firm lightly with your fingers — do not compact it hard, since air pockets in the soil are a feature, not a fault.

6. Leave headroom. Stop about half an inch below the rim so water does not overflow.

7. Water lightly. Enough to settle the soil around the roots. For succulents and cacti, repot dry and wait a week before watering at all.

The sulk afterwards

Most plants pause for two to four weeks after repotting. Some droop, some drop a leaf or two. This is transplant shock — repotting inevitably breaks fine root hairs, and the plant needs time to regrow them.

What helps:

• Keep it out of direct sun for a couple of weeks
• Hold conditions steady — no moving it around
• Water lightly and let the mix dry more than usual
• Do not fertilise for 4–6 weeks. Fresh mix already contains nutrients, and damaged roots cannot handle added salts

What does not help: repotting again, moving it repeatedly, or watering more because it looks unhappy. Leave it alone.

When not to repot

In autumn and winter, unless it is an emergency. A dormant plant cannot regrow damaged roots and will sit in fresh wet soil for months.

When the plant is already sick, unless the illness is root rot — in which case repotting is the treatment.

Immediately after buying, in most cases. Give a new plant two to four weeks to acclimatise to your home before adding the stress of repotting, unless it is clearly rotting or severely root-bound.

The alternative: top-dressing

In years when a plant does not need a bigger pot, refresh it instead. Scrape off the top two inches of old soil and replace it with fresh mix. This restores nutrients and improves the surface structure with none of the shock, and for large floor plants that are impractical to repot it is the standard approach.