Does your houseplant need a bigger pot?
A root at a drainage hole is a reason to look more closely. Check whether roots have filled the pot, then choose a modest size increase only if the plant needs room to grow.
Check the plant before choosing the pot
Use this guide for an established leafy houseplant in ordinary potting mix and a pot with drainage holes. It is a decision aid, not a complete repotting procedure. Orchids in bark, cacti, bonsai and reservoir systems need their own guidance.
Find your plant’s name and check its repotting preferences first. UNH Extension notes that clivia and amaryllis can thrive in crowded pots. A full-looking pot does not mean every species needs more space immediately.
1. Turn a clue into a root check
Roots at the drainage holes, unusually fast drying or slower growth can prompt an inspection. Penn State’s next step is to examine the rootball: the mass of roots and potting mix. A root poking out is a prompt to inspect, not a purchase instruction.
For a small pot you can handle comfortably, support the plant and mix while gently easing the container off. Do not yank the stem or force a stuck plant out. Look at the sides and underside: are roots circling the rootball, or so dense near the bottom that little mix is visible?
Record what you actually see. “Roots cover much of the lower rootball” is more useful than “it seems unhappy”. If substantial mix remains between the roots, a larger pot is not yet justified by crowding alone. Investigate the original symptom instead.
2. Decide whether more space is the goal
If the roots are crowded and you want the plant to grow larger, choose a modest increase. If you want to keep its size, simply buying a larger pot does not meet that goal; look for species-specific advice about maintaining size. This guide does not prescribe root pruning.
For routine repotting, favour the start of active growth. Do not translate a northern-hemisphere spring recommendation into the same calendar months everywhere. Yellowing alone does not prove a pot is too small: RHS lists yellowing among the possible effects of overpotting, too. Persistent wetness or a declining plant calls for investigation, not an automatic size increase.
3. Measure the growing pot, not its decorative cover
RHS gives a general starting point: a new pot about 2.5–5 cm (1–2 in) wider in diameter, and not much deeper. This is guidance, not a requirement to add the maximum. Compare the containers that actually hold the roots, and check their usable depth.
Extra mix can remain wet around a small rootball, reducing air around the roots. A larger pot does not inevitably cause harm, but slow growth and excessive watering increase the risk. Keep drainage holes; a decorative outer cover is not a substitute.
A fictional choice: 14 cm, 17 cm or 22 cm?
Imagine a leafy houseplant in a 14 cm growing pot. Inspection confirms crowded roots, and you want continued growth. The current pot and the proposed pots are round, similarly shaped, of comparable usable depth, and have drainage holes.
The 17 cm pot adds 3 cm to the diameter, within the RHS starting range. That is roughly 1.5 cm extra on each side, not 3 cm on each side. The 22 cm option adds 8 cm: it is too large a jump for this example. If inspection had shown an uncrowded rootball, neither purchase would follow from these clues alone.
Your five-line decision note
- Plant name and repotting guidance: ______.
- Observed rootball: crowded / not crowded / could not inspect.
- Goal: more growth / maintain size / investigate a problem.
- Current and proposed pot diameter: ______ → ______; depth suitable and drainage holes present: ______.
- Next action: pot up / keep the current size / get species-specific advice; reason: ______.