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Gardening glossary

Self-watering pot

A self-watering pot does not actually water the plant for you. It buffers the plant from your watering mistakes. A reservoir in the base of the pot holds water; a wicking platform or central capillary column draws water up into the soil whenever the substrate dries enough to pull it. When the substrate is moist, no water moves. When the substrate dries out, capillary action restarts the flow. The plant effectively waters itself from the bottom up.

The components:

1. **Reservoir** — a sealed chamber at the bottom of the pot, usually 1–5 litres for typical houseplant sizes. 2. **Wicking platform or column** — a perforated plate or central tube that connects soil to reservoir. 3. **Soil chamber** — sits above the reservoir, filled with a free-draining peat-free or coir-based potting mix. 4. **Overflow drain** — a hole partway up the reservoir to prevent overfilling. 5. **Fill port** — a separate inlet to top up the reservoir without removing the plant.

Where self-watering pots shine:

- **Holiday-friendly houseplants.** A topped-up reservoir keeps tropicals like peace lily, monstera, calathea, and ferns moist for 1–3 weeks. - **Office and busy-lifestyle plants.** Less frequent watering, fewer over-watering disasters. - **Container vegetables** — tomatoes, peppers, basil, and salad leaves all do well in self-watering tubs because they want consistent moisture without being soaked. - **Patio container herbs** in hot summers, where conventional pots dry out twice a day.

Where they do not work:

- **Succulents, cacti, snake plants, ZZ plants** — they want dry-out cycles. Sitting in a reservoir keeps roots damp continuously and rot is almost inevitable. - **Orchids and other epiphytes** with airy root systems. - **Plants in very low light** — even moisture in a dim corner is a recipe for fungus gnats and rot.

How to use one well:

1. **Fill the reservoir from the top** the first few times to establish capillary contact in the soil. Once contact is made, top up via the fill port. 2. **Let the reservoir run dry occasionally** — every 4–6 weeks, leave it empty for a few days. This rinses accumulated salts and ensures roots get a dry phase, which prevents anaerobic conditions. 3. **Flush from the top** every 2–3 months to leach fertiliser salts that would otherwise accumulate. Pour water in through the soil until it runs out the overflow. 4. **Top-feed with diluted liquid fertiliser** rather than adding fertiliser to the reservoir.

Done right, a self-watering pot is one of the few honest "set it and (mostly) forget it" gardening products on the market.

Where this comes up in our guides

Related terms

Capillary action

Capillary action is the upward movement of water against gravity through narrow spaces in a porous material — soil pores, paper towels, or plant xylem. It is the physical principle behind bottom watering, self-watering pots, and the rise of water from roots to leaves.

Wicking

Wicking is the use of a porous strip — usually cotton or synthetic cord — to move water from a reservoir into a pot via capillary action. The plant draws what it needs and stops, eliminating the over- and under-watering swings of conventional watering.

Bottom watering

Bottom watering is the practice of setting a potted plant in a tray of water so the roots draw moisture upward through the drainage holes, hydrating the soil evenly without wetting the foliage or crown.

Soak and drain

Soak and drain is a top-watering technique where you water thoroughly until liquid runs freely from the drainage holes, then let the substrate dry to the appropriate depth before watering again — never on a fixed schedule.

Drainage

Drainage is how quickly water moves through soil after irrigation or rain. Good drainage keeps roots from sitting in saturated soil, which is the leading cause of root rot in pots and beds.