How to repot a houseplant, step by step

Why repot?

In a pot, roots have only a small volume of potting mix to work with. Over time they fill it completely, while the mix settles, breaks down, and drains less well. Repotting gives the roots a little more room and a fresh medium, better drained and better aerated, where they can start growing again.

That doesn’t make it a yearly chore to do on principle: repotting too often or into a pot that is too big does more harm than good. The right approach is to look at the plant and its root ball, then decide.

Signs that a plant is root-bound

Roots are growing out of the drainage holes or showing at the surface of the mix.
The mix dries out very quickly, to the point that the plant needs frequent watering or wilts soon after being watered. Water runs through the pot too fast and the center of the root ball stays dry; leaf tips or edges may then turn brown.
Growth slows or stops in spring and summer, even though the plant is fertilized regularly.
The root ball is packed with roots: once the plant is out of its pot, roots circle around the root ball so densely that you can barely see any mix in the bottom third.
The plant becomes unstable: top-heavy, it is at risk of tipping over.
The mix has broken down: compacted and decomposed, it no longer lets water through properly.

To check, slide the root ball out of the pot carefully. If you can barely see any roots, simply put it back.

When to repot

The best time is spring, when the plant starts growing again. You can repot at another time of year if you must, but the plant recovers faster during its growing season. Fast-growing species may need repotting every year, slower ones only every two or three years.

Avoid repotting a plant that is sick, dormant, or starting to bloom. Some species even prefer to stay snug: the snake plant can wait about five years, the wax plant blooms better when slightly pot-bound, and the bush lily, which dislikes being disturbed, is repotted only after flowering, once its roots lift the plant or distort the pot. Check each plant’s profile before stepping in.

Choosing the pot

Size: a pot only 1–2 in wider. A container that is too big keeps the mix wet for too long.
Drainage: a hole in the bottom is essential. If you want a decorative cachepot, slip a pot with holes inside it.
Material: porous terra-cotta lets water evaporate through its wall and dries out faster; it suits succulents well. Plastic and glazed pots are watertight and hold moisture longer.
Weight: for a tall or top-heavy plant, such as an old jade plant, a heavy pot keeps it from tipping over.

Why not go big right away? In an oversized pot, the volume of fresh mix stays wet around the root ball for a long time and root aeration drops. Instead of growing into the new mix, the roots rot. The risk is highest with a slow-growing plant, in winter, or when you have a heavy hand with the watering can.

No gravel in the bottom

A layer of gravel, stones, or broken pot shards in the bottom of a pot does not improve drainage, despite a stubborn belief. Instead, it raises the zone where water collects, closer to the roots, and can waterlog the mix to the point of killing the plant. A single shard over the drainage hole is all you need to keep the mix from washing out.

Choosing the potting mix

Use a potting mix made for containers, never garden soil: it carries too many microorganisms and can also bring in diseases and pests. Most commercial mixes are soilless: lightweight and clean, based on peat or coconut coir, lightened with perlite or vermiculite, sometimes with pine bark or coarse sand.

Match the mix to the plant: cacti and succulents, for instance, need a very fast-draining mix. Each Verdepedia profile gives the recommended potting mix. Moisten the mix before use so that it absorbs water evenly afterward.

Step by step

Prepare the new pot: clean, washed if it has been used before. Add a layer of mix to the bottom and firm it lightly, so that the top of the root ball will sit about 1 in below the rim: that space holds water when you water.
Remove the plant: hold the pot down and pull the plant up by its main stems, or turn the pot upside down with the root ball between your fingers and knock the rim against a hard surface. Lay a large pot on its side to slide the root ball out. Slightly dry mix that has shrunk a little comes away more easily.
Inspect the roots: tease out those circling the root ball and trim them lightly if needed. If the root ball is a tight mass, loosen it by hand or score it lightly with a knife so the roots can spread. Remove dead, brown, mushy roots.
Set the plant at the same depth as before, without burying the stems or the crown. Fill in around the sides with fresh mix, pressing it with your fingertips to remove air pockets, but without packing it so hard that it restricts water and air movement.
Water thoroughly until water runs out of the drainage hole, let it drain, then empty the saucer. Peat-rich mix wets poorly on the first pass: repeat several times to soak it well.

Special cases

Very large plants: when repotting is no longer practical, replace the top 2–3 in of mix with fresh potting mix about every two years. This is called top-dressing.
Keeping the same size: if you don’t want the plant to get bigger, trim the outer part of the root ball, put the plant back in the same pot with fresh mix, and cut back some of the foliage to rebalance roots and stems.
Cacti: handle them with heavy gloves or wrap them in several layers of newspaper. Choose a pot only slightly larger and a very fast-draining mix, and wait a few days before the first watering.
Plants overrun by gnats: repotting into fresh mix and throwing out the old one is one of the solutions covered in Fungus gnats.

After repotting

Keep the plant out of direct sun for a few weeks and don’t fertilize it while the roots grow into the new mix; for a jade plant, allow about four months. After that, water cautiously, only when the mix starts to dry, especially during the first few weeks: that is when fresh mix is most likely to stay too wet. To know when to water, follow the guidance in Water by observation, not by the calendar.

Slight drooping during the first few days is normal. Persistent yellowing of many leaves points instead to a pot that is too big and a mix that is too wet. But the same symptom can come from a spot that is too dark, a temperature that is too low, a sudden temperature drop, or cold air currents: check these before drawing conclusions.

At a glance

Stage	What to remember
Deciding	Roots coming out or circling, mix drying too fast, growth stalled
Timing	In spring, during active growth; never on a sick plant or one in bloom
Pot	1–2 in wider, with a drainage hole, no gravel layer
Potting mix	Container mix suited to the species, never garden soil
Planting	Same depth, roots teased out, air pockets filled without packing
Recovery	Careful watering, no direct sun or fertilizer for a few weeks

To sum up: a successful repotting starts by looking at the roots, happens in spring into a pot only slightly larger, and ends with a few weeks of gentle care. Done well, it only needs repeating every one to three years for most houseplants.