Free tool
The right pot, for your plant and your habits
Five questions, four of them about you. Free, no signup — and if your plant does not need repotting yet, this will say so.
Why a pot deserves its own tool
A leaf is a report on the roots
By the time the leaves say something is wrong, it went wrong underground, weeks earlier. You never get to watch the roots. You only get to choose the four things that decide what happens to them.
- Pot
- How much water they sit in
- Mix
- How much air is left between them
- Light
- How fast the plant drinks it
- Watering
- How often you fill it back up
Four parts of one system — which is why this asks about you, not only about the plant. And the pot gets its own tool because it is the one you cannot walk back: mix can be amended, a plant can be moved to a brighter wall, watering can change this week. The pot is bought once, and everything else has to work inside it.
So — what are you growing?
Three things worth knowing before you buy anything
A pot that is too big is the harder mistake to undo
Roots do not fill a pot evenly and instantly. Soil they have not reached yet holds water with nothing drinking it, and roots sitting next to permanently wet soil run out of oxygen. That is what people are usually describing when they say a plant was overwatered — the pot was doing as much of it as the watering can. One size up at a time is not caution, it is the whole method.
The gravel layer at the bottom does not help
Water does not cross from fine soil into coarse gravel until the soil above is fully saturated. Adding a gravel layer raises the wet zone instead of draining it, and costs you root space. What actually drains a pot is a hole in it and a mix with enough coarse material through the whole volume.
A decorative pot with no drainage hole is a vase
You can still use one — keep the plant in a plain nursery pot and set that inside the decorative one, then lift it out to water and let it finish dripping before it goes back. That is what a cachepot is. What does not work is planting directly into a sealed pot of ordinary potting mix and watering carefully — no amount of care substitutes for an exit. (Semi-hydro setups in LECA or pumice do work in a sealed reservoir, but that is a different growing method, not a careful version of this one.)
Reference
Root systems and the pot shape each one wants
Shape comes from the roots alone — it is the one part of the answer your habits do not change.
| Diagram | Root system | Pot shape | Why |
|---|---|---|---|
| Shallow fibrous Fine roots that stay near the surface | Azalea pot — three-quarter depth | Fine, dense roots that work through the top of the pot rather than diving. A pot much deeper than it is wide leaves soil underneath them that stays wet longer than the roots ever reach. | |
| Spreading rhizome Creeps sideways on a thick underground stem | Wide and low — well under azalea depth | Grows outward from a horizontal rhizome. It runs out of width long before it runs out of depth, and can split a pot doing it. | |
| Epiphytic / coarse-rooted Thick roots that grew on bark or rock, not in soil | Just under standard depth — prioritise airflow over volume | Thick, ropey roots that evolved to grip bark or rock, not to sit in soil. Air around them matters more than how much soil they get. Climbing aroids, epiphytic anthuriums and bird's-nest ferns all want the same thing from a pot. | |
| Tuberous / water-storing Keeps its own water in a tuber underground | Standard depth — but snug across | Carries its own water reserve in a tuber or thick fleshy roots. It can shrug off a dry pot. It cannot survive a permanently wet one. | |
| Deep anchoring Few thick roots heading straight down | Full depth, and heavy | Thick anchoring roots that use the whole depth of a pot rather than the top few inches. What keeps one of these upright is the weight of the pot and the width of its base, not how tall the pot is — a tall narrow pot actually tips more easily. | |
| Shallow succulent Shallow roots that drink fast, then dry right out | Low and wide — two-thirds depth | Fine surface roots built to catch a brief rain and then dry out completely within a day or two. |
Every plant in the tool
37 plants so far. Starter size is what to use for a rooted cutting or a bare-root plant, before any of the questions above apply.
| Plant | Root system | Pot shape | Rot risk | Starter size |
|---|---|---|---|---|
| African mask plant Alocasia × amazonica 'Polly' | Tuberous / water-storing | Standard depth — but snug across | High | 4 in · 10 cm |
| Aloe Aloe vera | Shallow succulent | Low and wide — two-thirds depth | High | 5 in · 13 cm |
| Angel wings Caladium bicolor | Tuberous / water-storing | Standard depth — but snug across | High | 5 in · 13 cm |
| Arrowhead vine Syngonium podophyllum | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Low | 4 in · 10 cm |
| Baby rubber plant Peperomia obtusifolia | Shallow fibrous | Azalea pot — three-quarter depth | High | 3 in · 8 cm |
| Bird's nest fern Asplenium nidus | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Medium | 5 in · 13 cm |
| Birkin Philodendron 'Birkin' | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Medium | 4 in · 10 cm |
| Boston fern Nephrolepis exaltata | Spreading rhizome | Wide and low — well under azalea depth | Low | 6 in · 15 cm |
| Calathea orbifolia Goeppertia orbifolia | Shallow fibrous | Azalea pot — three-quarter depth | Medium | 5 in · 13 cm |
| Chinese money plant Pilea peperomioides | Shallow fibrous | Azalea pot — three-quarter depth | Medium | 4 in · 10 cm |
| Dragon tree Dracaena marginata | Deep anchoring | Full depth, and heavy | Medium | 6 in · 15 cm |
| Echeveria Echeveria spp. | Shallow succulent | Low and wide — two-thirds depth | High | 3 in · 8 cm |
| Fiddle leaf fig Ficus lyrata | Deep anchoring | Full depth, and heavy | Medium | 6 in · 15 cm |
| Flamingo flower Anthurium andraeanum | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | High | 5 in · 13 cm |
| Giant bird of paradise Strelitzia nicolai | Deep anchoring | Full depth, and heavy | Medium | 8 in · 20 cm |
| Heartleaf philodendron Philodendron hederaceum | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Low | 4 in · 10 cm |
| Jade plant Crassula ovata | Shallow succulent | Low and wide — two-thirds depth | High | 4 in · 10 cm |
| Mini monstera Rhaphidophora tetrasperma | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Medium | 5 in · 13 cm |
| Money tree Pachira aquatica | Deep anchoring | Full depth, and heavy | Medium | 6 in · 15 cm |
| Nerve plant Fittonia albivenis | Shallow fibrous | Azalea pot — three-quarter depth | Low | 3 in · 8 cm |
| Peace lily Spathiphyllum wallisii | Shallow fibrous | Azalea pot — three-quarter depth | Low | 5 in · 13 cm |
| Pink Princess Philodendron 'Pink Princess' | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Medium | 4 in · 10 cm |
| Polka dot begonia Begonia maculata | Shallow fibrous | Azalea pot — three-quarter depth | Medium | 4 in · 10 cm |
| Pothos Epipremnum aureum | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Low | 4 in · 10 cm |
| Prayer plant Maranta leuconeura | Shallow fibrous | Azalea pot — three-quarter depth | Low | 4 in · 10 cm |
| Rubber plant Ficus elastica | Deep anchoring | Full depth, and heavy | Medium | 6 in · 15 cm |
| Silver satin pothos Scindapsus pictus | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Medium | 4 in · 10 cm |
| Snake plant Dracaena trifasciata | Spreading rhizome | Wide and low — well under azalea depth | High | 4 in · 10 cm |
| Spider plant Chlorophytum comosum | Shallow fibrous | Azalea pot — three-quarter depth | Low | 4 in · 10 cm |
| Swiss cheese plant Monstera deliciosa | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Medium | 6 in · 15 cm |
| Swiss cheese vine Monstera adansonii | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Medium | 5 in · 13 cm |
| Thai Constellation Monstera deliciosa 'Thai Constellation' | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | Medium | 5 in · 13 cm |
| Velvet cardboard anthurium Anthurium clarinervium | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | High | 4 in · 10 cm |
| Wax plant Hoya carnosa | Epiphytic / coarse-rooted | Just under standard depth — prioritise airflow over volume | High | 4 in · 10 cm |
| Zebra alocasia Alocasia zebrina | Tuberous / water-storing | Standard depth — but snug across | High | 5 in · 13 cm |
| Zebra haworthia Haworthiopsis attenuata | Shallow succulent | Low and wide — two-thirds depth | High | 3 in · 8 cm |
| ZZ plant Zamioculcas zamiifolia | Tuberous / water-storing | Standard depth — but snug across | High | 5 in · 13 cm |
We grow the plants we drew this for
This tool came out of potting our own collection, and the reasoning it shows you is the reasoning we use on our own shelf. The journal reports what those plants actually do every two weeks, mistakes included. Nothing is for sale.
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