Gardening glossary
Wicking
Wicking is the simplest possible self-watering system. A single length of absorbent cord runs from the soil of a potted plant down into a reservoir of water below the pot. Capillary action pulls water along the cord and into the soil whenever the soil dries out enough to need it. The system regulates itself — the drier the soil, the steeper the moisture gradient, and the faster water moves up the wick.
How to set up a wick:
1. **Choose the wick material.** Cotton clothesline, acrylic mop rope, microfibre boot laces, or strips of an old t-shirt all work. Avoid waxed or coated cord — water cannot move through it. 2. **Thread one end through a drainage hole** of the pot from outside to inside, leaving 10–15 cm exposed inside the pot. 3. **Bury the inside end in the soil.** Run it up through the root ball if possible, so the wick contacts moist soil throughout the pot. 4. **Set the pot above a reservoir** — a tray, a small tub, or a glass jar — with the outside end of the wick submerged in water. 5. **Top up the reservoir** as it drains. A 1-litre reservoir typically lasts a small houseplant 5–10 days; a holiday-watering setup can use a 5-litre bucket.
Where wicking shines:
- **Holiday plant care.** A wick system lets a houseplant go 1–3 weeks without attention. - **Tropicals that hate drying out** — calatheas, prayer plants, ferns, peace lily. - **Office plants** where consistent watering is hard. - **Seedling trays** — a wick or capillary mat under the tray keeps cells evenly moist without flooding.
Where wicking does not suit:
- **Succulents, cacti, snake plants, and most plants that want full dry-out cycles.** A wick keeps soil too consistently moist for them. - **Plants prone to root rot under the best of conditions** — wicks can over-deliver if the wick is too thick or the soil too dense. - **Very large pots** — capillary action only carries water so far up; a 50 cm deep pot is too tall to wick from the bottom.
For greenhouse and nursery use, capillary matting is a flat felt version of the same idea — pots sit on a moist mat and draw water through their drainage holes by capillary action.