Make your own wicking planter box
© Kat Lavers
Pots are great for renters, apartments, balconies, courtyards and keeping plants like herbs or salad close to the back door mean you can harvest at a moment's notice, even in bad weather. But keeping plants alive in pots over summer can be hard work. Soil in a small black pot can heat up fast and bake fragile plant roots - especially when positioned in a sunny concrete courtyard. In hot weather water evaporates quickly and pot plants may need to be watered more than once a day.
Enter the wicking box! These clever systems use the power of capillary action to keep soil at the root zone constantly moist by drawing water up from a reservoir at the base of the pot. The surface stays dry preventing evaporative losses and germination of weed seeds. It's like giving your plants a glass of water so they can drink whenever they're thirsty! Wicking boxes are easy to make at home from salvaged materials.
To build your wicking box, you will need:
- Polystyrene box / plastic container, with no holes in the base
- Potting mix / sandy soil mix
- Electric drill
Step 1: Drill two holes about one third of the way up from the base of the box. These are overflow holes that prevent the box from flooding in heavy rain or if too much water is added. It's a good idea to move your box to its final location at this stage as it will become very heavy once filled.
Step 2: Fill the polystyrene box with gravel or sand up to the level of the overflow holes.
Step 3: Drill several holes around the base of the pipe below the overflow level to allow water to flow quickly into the reservoir.
Step 4: Trace the outline of the pipe towards one end of your hessian or shade cloth that has been cut a little larger than the size of the base of your box. Make a few cuts across this circle. Insert the pipe into the wicking box, fit hessian over pipe and arrange hessian to cover gravel. Hessian acts as a permeable barrier between the gravel and soil.
Step 5: Fill box with potting mix, plant and water to settle in seedlings. Mulch with a thick layer of dried leaves, shredded paper or straw to reduce water loss by evaporation.
Step 6: Pour water into the pipe until it starts to run out the over flow hole to fill reservoir. It may take 2-3 days for the soil to become fully moist from the reservoir and you will need to top up the reservoir regularly during this period. Alternatively, you can speed up the process by watering the soil once to get started and allow the wicking effect to maintain moisture levels thereafter. Check the water level in the pipe regularly and top up as needed.