Should my plant be in a self-watering pot?

Water sits in a reservoir at the bottom. Above it, separated by a platform, the compost; through the platform, a wick, or a leg of compost that reaches the water. Capillary action pulls water up as the compost above dries, so the compost stays evenly, lightly moist as long as there is water below. You top up the reservoir through a tube or a slot, and an indicator or a float tells you when it is low.

Two consequences. The compost never dries out, which is the point. And there is no drainage — the run-off you would normally throw away is the reservoir, so anything you add to the water (feed, minerals from the tap) accumulates rather than flushing through.

Plants from wet ground that hate drying out: peace lily, ferns (Boston, maidenhair, bird's nest), calathea and maranta, spider plant, pothos and philodendron in a bright spot where they drink, umbrella plant, most herbs on a kitchen sill, and seedlings and cuttings. For these a self-watering pot removes the one thing that kills them — a missed watering — and they visibly do better.

Plants that store water and want to dry out fully: snake plant, ZZ, succulents and cacti, jade, aloe, ponytail palm, yucca, string of pearls and hearts. In a self-watering pot these rot at the roots within a season, however careful you are, because the design is the overwatering. The same is true of any plant in a dim room: it drinks little, the wick supplies anyway, and the compost stays sodden.

The middle — monstera, rubber plant, dracaena, ficus — can go either way and depends on the light: a monstera drinking hard in a bright room is fine; the same plant in a corner is not.

Fill the reservoir, then let it run dry before you refill.

This is the rule that makes the pot safe: a few days empty lets air back into the compost and the roots breathe. A reservoir kept permanently full is a bog.

Water from the top occasionally

— once a month, enough to run through into the reservoir — to flush the minerals and feed salts that otherwise accumulate.

Feed at a quarter strength,

if at all, because nothing flushes out.

In winter, let it stay empty longer.

The plant drinks a fraction of its summer need; a reservoir that lasted a week in July lasts a month in December, and topping it up on the July schedule is how a peace lily rots in January.

Lift the inner pot now and then

and look at the compost at the bottom and the roots. Sour smell, dark and slimy: it has been too wet. White, firm roots reaching for the water: right.

For an ordinary pot, “water every eight days” means eight days between drinks. For a self-watering pot the question is how often the reservoir needs filling, and that is not the plant's interval but the reservoir's capacity divided by the plant's thirst — days, then weeks, as the seasons turn. Sabz handles this as its own case: a plant marked as self-watering gets a reservoir schedule rather than a watering one, and its Check-up weighs the reservoir when something goes wrong, because overwatering in a reservoir and fungus gnats in a reservoir have their own fixes — let it run dry, then dry the surface — which the ordinary advice gets wrong.

Yellowing lower leaves, a sour smell, a soft base — the roots are sitting in water. Empty the reservoir, lift the inner pot, and let the compost dry a good way down before refilling; if the roots are brown and soft, it is root rot and the plant needs fresh compost and, honestly, a different pot.

Small flies around the pot — fungus gnats, which breed in compost that never dries. Let the reservoir run dry, let the surface dry fully, and put a layer of grit on top. The fungus gnats guide has the rest.

Crust on the compost, brown leaf tips — minerals accumulating because nothing flushes. Water through from the top monthly, use rainwater or filtered water, feed less. See brown leaf tips.

Thrives in one: peace lily, Boston fern, calathea, spider plant. Never in one: snake plant, ZZ plant, jade plant, aloe.

Are self-watering pots good for houseplants?

For the ones that want constant moisture — peace lily, ferns, calathea, spider plant, herbs — yes: they remove the missed watering that kills them. For the ones that store water and want to dry out — snake plant, ZZ, succulents, jade, aloe — no: the pot itself is overwatering, and they rot within a season. Match the pot to the plant, not the other way round.

How often do you fill a self-watering pot?

When the reservoir is empty, and not before — a few days empty lets air back into the compost. In summer that may be weekly; in winter a month or more. Do not top it up on a schedule; let the indicator, or a look down the tube, decide.

Can a plant get root rot in a self-watering pot?

Yes, easily, if it is a plant that wants to dry out or the reservoir is kept permanently full. The signs are the same as any overwatering: yellow lower leaves, a sour smell, a soft base. Empty the reservoir, let the compost dry, and move the plant to an ordinary pot if it is one of the dry-loving kinds.

Why does my self-watering pot have fungus gnats?

Because the compost surface never dries, and that is where gnats lay. Let the reservoir run dry until the top few centimetres are dry, keep it that way by filling less often, and put a layer of grit or sand on the surface. Sticky traps catch the adults while it dries.

Do you still need to water from the top?

Once a month, enough to run through into the reservoir. It flushes the minerals from tap water and any feed that would otherwise build up in compost that never drains. Use rainwater or filtered water if you are in a hard-water area.

The RHS's page on grey mould is not about pots, but it is the reference for what happens to plant tissue kept wet and still, which is the self-watering failure in one sentence. Sabz's Check-up asks whether the plant is in a self-watering pot before it reads the history, because the same three waterings mean something different with a reservoir underneath — and it gives the reservoir version of the fix.