I tried a couple of different designs. The first was simply a dish-towel draped into a bucket of water, however, I couldn't get consistent distribution of water across the seedling area which was next to the bucket - I think the breeze dried the cloth faster than the capillary action could replenish the water.
The second design again used a dish-towel, but this time I draped it over a flat piece of plastic and sat it in a tray just above the water level. This worked somewhat better than the first design, particularly when I added a little extra cloth to provide greater thickness to the capillary mat. However, evaporation again made the watering inconsistent, drying the mat out faster than it could be replenished.
Thankfully, it was third time lucky. The latest design works a treat, plus it was simple and cheap to make.
- a 35 litre under-bed storage container with a lid (on special for $8 at the hardware store)
- an old towel (few dollars from a second hand store)
- a Stanley knife (a sharp hobby knife)
- a blow-torch (if needed)
The lid of the storage container proved to be quite brittle and was prone to shattering and/or cracking when I tried to cut it where the towel was to be placed. This is where careful use of the blow-torch came in. I used the torch to heat the area to be cut until it was soft and pliable and then cut the now soft plastic material, making an inch-wide slot at both ends of the lid. Take care not to burn the plastic - you want it just warm enough to cut. Heat the plastic in stages if necessary. The finished result is pictured below (hopefully you can see the slot running the width of the lid):
|Inch-wide slot (highlighted) with towel ready for insertion|
I then fed each end of the towel into the appropriate slot in the lid, put the now towel-covered lid in place, filled the storage container with water (the hose easily fits through the one inch slot) and then placed the newly-filled seed trays on top.
|Finished capillary bed|
The beds have worked marvelously. I made three of them and they've all got little seedlings sprouting up through the propagation mix. I've had no problems with them drying out while I've been away at work.
With hindsight - if I had been able to find them on special I'd have used different storage containers - the much lower 20 litre ones would've worked just as well and have about the same surface area for the seed trays. I'd also have looked for a container with a more pliable lid - it'd have made cutting the slots a lot easier and I'd have been able to avoid using the blow-torch.