What time of year should I repot houseplants?

March, April or May if you are north of the equator, and September, October or November if you are south of it. GrowSpot reads that window from the latitude of your home area rather than from the date alone, which is why a single month is the wrong shape of answer.

How often should you repot houseplants?

Published cycles run 18 to 24 months, and the anchor our own check starts from is held between 12 and 48 months before any adjustment for the plant and its pot. We do not publish the per-species figure, because those values were machine-filled rather than curated. Either way it is a check-the-roots interval rather than a calendar appointment.

Can I repot in winter?

The app will not suggest it. Outside the spring window the repot hint stays down whatever the roots look like, because the plant has the least capacity to recover then. Nothing stops you doing it if a plant is in trouble; it just is not the moment the app will pick for you.

My plant dries out in a day. Does it need repotting?

Not on that evidence alone. A terracotta pot with a gritty mix in high summer dries about seven times faster than a glazed pot of ordinary mix in midwinter, with the same roots in it. Go and look at the roots instead.

Does GrowSpot tell me when to repot?

It raises a soft hint to go and check the roots, when four things are true at once: the container is one repotting applies to, no extreme-weather alert is running, you are inside your hemisphere's spring window, and enough time has passed since the last repot. It does not tell you to repot on a date.

Why does the app go quiet during a heatwave?

Repotting costs the plant root contact at the moment it needs it most, so a heat or cold alert on an outdoor plant suppresses the hint until the alert clears. Feeding is held back on the same signal.

When to Repot a Houseplant

Ask when to repot and you get a season back. Spring, say most of the results; early spring, says the Penn State Extension page; autumn, says a garden centre on the same first page of results, because growth is slowing and transplant shock is smaller. They cannot all be describing the same plant.

GrowSpot has to answer this without asking you anything, so the answer had to become a test rather than a season. There are four conditions in it. Three of them are never mentioned in the advice above, and the one that is mentioned is the one that moves depending on where you live.

Worked example: Peace lily a metre back from a north window, air 21 °C and 45% humidity, light airflow. Your spot will score differently. Run it for your own spot →

Spring is not a month. It is a hemisphere.

The app reads the spring window from the latitude of your home area, so the same calendar month is inside the window for one reader and outside it for another. Nothing on the first page of that search makes the distinction, which is a quiet problem for anyone reading northern advice in March in Melbourne.

These are the two windows, read from the check itself:

The filled blocks are the months the repot check treats as spring, by hemisphere, read from the latitude of your home area rather than from the date alone: March, April, May in the north, September, October, November in the south. Every result on the first page of this search assumes the top row.

Note what this does to the most common piece of repotting advice in the world. "Repot in spring" is correct for both columns and useful for neither, unless it says which spring. A plant you bought last week sits outside all of this, because the interval it reads starts from your records.

Spring is necessary. It is not sufficient.

Three more conditions sit alongside the calendar, and every one of them can keep the app quiet in the middle of April. Extreme weather is the one people find surprising: if a heat or cold alert is running for a plant standing outside, repotting is held back, on the same reasoning that holds back feeding. Root disturbance is a cost, and you do not want to spend it in the same week as a heatwave.

Here is the whole test, run one condition at a time:

The situation	What GrowSpot does
Spring, and it has been in that pot for years	Raises the hint
Same plant, but it is autumn where you live	Silent: outside the spring window
Spring, but you repotted it last year	Silent: repotted too recently
Spring, and a heat or cold alert is running outdoors	Silent: extreme weather outside
Spring, but it is planted in the ground	Silent: repotting does not apply here
Spring, but it is in semi-hydro	Silent: repotting does not apply here
Autumn, in the ground, repotted last month	Silent: repotting does not apply here

Every row is the same plant, changed one condition at a time, run through the repot check itself. The hint needs all four conditions at once, so any single row that fails is enough to keep the app quiet. The last row fails three of them at once and the app names the container, because that test runs first.

The last row is worth a second look. That plant fails three conditions at once, and the app names the container rather than the season, because the container test runs first. If repotting does not apply to how the plant is growing, nothing after that matters.

The sign everyone gives you is the one that lies

Every source on that first page lists the same tells: roots out of the drainage holes, roots circling the surface, the plant going over because it is top-heavy, and soil that dries out a day or two after a deep watering. The first three are observations of roots. The fourth is not, and it is the one people act on, because it is the one you notice without doing anything.

Drying speed is what our watering maths is built to model, so we can put a number on how far it moves without any roots involved. Pot material, potting mix and the season each scale it, and they multiply:

Same plant, same room	How fast the pot dries	Gap between waterings
A glazed pot with ordinary potting mix, midwinter	×0.5	×2
A glazed pot with ordinary potting mix, average day	×1	×1
A terracotta pot with ordinary potting mix, average day	×1.15	×0.87
A terracotta pot with a gritty cactus mix, average day	×1.44	×0.7
A terracotta pot with a gritty cactus mix, high summer	×3.59	×0.28

Relative to the middle row, computed from the pot factor, the mix factor and the season factor GrowSpot uses. Nothing about the roots changes down this table: the top and bottom rows are 7.2 times apart on drying speed alone. That is why "it dries out in a day now" is not, on its own, a root-bound plant.

The same plant with the same root ball dries seven times faster at the bottom of that table than at the top. Nothing in those rows is a root. If you moved a plant into terracotta with a grittier mix in April and it started drying out in a day by July, you have reproduced the whole effect without the plant doing anything at all. The watering guide works through the same three factors from the other direction.

This is not an argument that your plant is fine. It is an argument that the drying test cannot tell you either way, so it is worth going and looking at the roots rather than inferring them.

Two containers where the question does not apply

Repotting assumes there is a bigger pot to move to. For two of the six ways people grow things indoors, there is not, and GrowSpot never raises the hint for them:

What it is growing in	Does the repot check run?	Does pot width change the threshold?
A plastic or glazed pot	Yes	Yes
A terracotta pot	Yes	Yes
A nursery pot inside a decorative one	Yes	Yes
Mounted on a board or slab	Yes	No, a board has no width to read
Planted straight into the ground	No, there is no bigger pot to move to	Not applicable
Semi-hydro or water culture	No, there is no bigger pot to move to	Not applicable

Read out of the container rules themselves. Two of the six have no repotting step at all, so the app never asks you to check the roots on them. Mounted plants are the odd one: they do get repotted onto a bigger slab, but a slab has no diameter the pot-width rule could read.

Mounted plants are the interesting exception. A staghorn fern on a board does get moved to a bigger board, so the check still runs, but the pot-width rule has nothing to read, because a slab has no diameter. That is one narrow rule declining to apply itself rather than an entire feature switching off.

What to do with your own plant

Wait for your own spring, not the one in the article. Then check the roots rather than the soil, because the soil has three other explanations. If the plant is in the ground or in water, stop reading about repotting. And if there is a heat or cold snap in the forecast, let it pass first, since the plant has nowhere to recover to. That alert is one of five the app watches, and only two of them follow a plant indoors.

Where the plant stands is a separate question, and it is the one that decides whether it grows at all afterwards. You can put a number on that in about a minute with the free spot checker, no download, or work through the light check first if the plant has been sulking.

The thresholds and windows above are read out of the repotting check itself, and the per-species anchor it starts from is held between 12 and 48 months. We do not publish that anchor for individual species, because those values were machine-filled rather than curated. Drying multiples come from our watering model, calibrated against our own plants.

Plant photo credits