Repotting a houseplant: when and which pot size to choose?

Repot a houseplant in spring, as soon as roots grow out of the drainage hole or the plant no longer sits well in its pot. Choose a new pot that is 2 to 4 cm wider in diameter than the old one.

When should you repot a houseplant?

The best moment is spring, at the start of the growing season. The plant recovers quickly and fills the new pot with roots. You do not need to repot every year. Many houseplants do fine in the same pot for three or four years, as long as you top up the soil now and then. Watch for these signs:

• Roots grow out of the drainage hole or on top of the soil.
• Water runs straight through the pot and the soil is dry again within a day.
• The plant tips over or looks top-heavy compared to its pot.
• Growth has stalled even though you water and feed it.
• The potting soil has become compacted, pulls away from the rim or smells musty.

If you notice one of these signs in winter, wait for the light to return if you can. Only repot straight away for rotting roots or a pot that is falling apart.

How much bigger should the new pot be?

Go for a pot that is 2 to 4 cm wider in diameter. If your plant sits in a 21 cm pot, 24 or 25 cm is the next step. For a plant in a 40 cm pot, choose 44 cm. Bigger jumps seem handy, but they cause trouble: a lot of wet soil stays around a small root system, and that is exactly where root rot starts.

Always measure the inside diameter at the top of the pot, not the outside, because the rim and wall thickness add up. In our guide on choosing the right plant pot size you can read how to measure precisely. Nursery pots with a code such as C3 or C5 refer to volume, which we explain in pot size C2, C3 and C5.

How do you repot a houseplant step by step?

You need a clean pot, fresh potting soil and a surface that can get dirty. Choose peat-free potting soil if you can, see the advice from Milieu Centraal on sustainable gardening (in Dutch).

• Water the plant a day beforehand, so the root ball comes loose more easily.
• Turn the pot over, support the stem and gently work the root ball out. Do not pull on the stems.
• Loosen the roots at the bottom and cut away black, mushy or rotting roots.
• Put a layer of fresh soil in the new pot, so the root ball ends up at the same height as before. Leave 2 cm below the rim for watering.
• Fill the sides with soil and press lightly, without packing it down.
• Water the plant and let it drain well before it goes back to its spot.

Can you repot a houseplant into a decorative pot without a hole?

Yes, and it is often the neatest solution. Leave the plant in a regular grow pot with a drainage hole and place that inside the decorative pot. Allow about 1 to 2 cm of play all around, so you can always lift the inner pot out. Water over the sink, let it drain and then put the plant back. That way the roots never stand in water.

How to do this exactly is covered in using an inner pot in a decorative pot without a hole. When you repot, the inner pot simply goes up a size, so the decorative pot needs to be roomy enough too. Check that before you start.

Which pot size suits a large houseplant?

With large plants it is about stability and weight. A plant of 1.5 metres in a 40 cm pot can usually move up to 44 or 45 cm. A 50 cm pot full of wet potting soil easily weighs tens of kilos. Think about the spot before you fill it, and move the pot empty if needed, or put it on a plant stand with wheels.

If the pot stands on a wooden floor, use a saucer or a felt pad. You will find more on diameters of 30, 40 and 50 cm and floor protection in choosing a large indoor plant pot.

How do you help the plant settle in after repotting?

Put the plant back in a bright spot without harsh sun. Water sparingly for the first weeks, so the new soil can dry out slightly between waterings. You do not need to feed in the first four to six weeks, because fresh potting soil already contains enough nutrients. A few yellow leaves in the first week are normal and no reason to worry.