Wicking boxes can be used either as part of an intensive water-wise growing system, or just a good way to keep those herbs alive that you usually forget to water. And you can make one yourself out of junk for next to nothing!
A wicking box functions the same way as a wicking bed (see how to make a wicking bed for the full rundown).
Any wicking system of this kind relies on a couple of things: a contained bottom reserviour filled with gravel, a watering pipe, and a container to hold the soil and plants above. In a wicking box, this system is all in the one vessel.
A wicking bed works by filling the gravel reservoir with water via the watering pipe, which then ‘wicks’ up into the soil above, watering the plant roots within that soil. Because the plants are watered from below (and heavily mulched on top of the soil), a wicking system is very water efficient and reduces heat and water stress in the plants, as there is always water available at their root zone.
At our last PDC at Milkwood Farm, Adam Kennedy rocked up to do some workshops with the class. As one of the workshops, he made some wicking boxes for some herbs. Three months later, those herbs are still going strong. I wouldn’t say we forget to water them, it’s more that we know they’re in good hands…
Here’s what we used. You could substitute any of these materials for something that would do a similar job:
3 months later, both these wicking boxes are growing strong and full of herbs (they’re not bouncing out of their boxes, but that’s the growth cycle at this time of year at our farm – it’s slowdown time).
We’ve also sowed a bunch of small seedlings into the third wicking box, and they are growing well also. So I would say that wicking boxes are a little winner of a DIY project, all said and done!
I should add that here are many variations on this idea, both in what you could use for a vessel, and the exact ratios of gravel to soil, permeable membranes, etc etc etc. But the idea is solid, and it works.
Many thanks to Adam Kennedy for his experimenting and helpful instruction on how to make wicking boxes.