The Level 1 Wicking (wicking cup) instructable introduces the the basic principles of efficient and easy watering from below the soil profile. Now we apply these principals to make self-watering pots that make for faster growing and more productive fruit and veg, with minimal effort.
Step 1: Be Creative and Choose Your Weapon
You will need a fully sealed pot, bucket, bathtub, IBC or any sealed container - be creative! The introductory image shows a pot plant that I sealed (drainage holes at the bottom) using some silicone to allow them to be re-purposed into wicking pots. Its even easier with a 60 cent bucket pictured above. Next you will need some some river rock, an old pillowcase and some planting soil.
Step 2: Build Your 3 Key Zones
Zone 1 (filter media) - I have filled the bottom 150mm of each bucket with 20mm rock from my garden, you could use scoria rock, golf balls, crushed bricks....basically anything that will hold plenty of water in between it and support the soil on top of it. This will be your water reservoir so the thirstier the plant your want to grow, the larger you should make this zone.
Zone 2 (transition layer) - I used some old bed sheet cut up. I have also used pillow cases, old clothing and if you want to be really fancy you could try geofabric from your local hardware store. This layer separates your soil layer from your filter media (zone 1) layer and it needs to be able to absorb water. You will see I pushed the bed sheet into the filter media zone a little - this is to allow the water to make contact with the sheet even when the reservoir is low.
Zone 3 (soil/growing zone) - I just made my own soil mix here and then simply added it to zone 2. I have found 150mm to 300mm works nicely. Note - water will typically only 'wick' up a maximum of 300mm so don't get too excited about the depth of zone 3.
You will see I have added a short length of 40mm wide conduit (pipe) to each wicking pot. This is critical and ensures you can fill your water reservoir from the top - make sure the conduit goes all the way to the bottom of your filter media zone.
Step 3: Overflow, Mulch and Watch
Its important that you create an overflow for excess water to exit your new wicking pot. I have simply drilled three small holes as you can see in the picture attached - drill these just below your zone 2 (sheet, pillow case etc) so that soil does not block the holes.
I always mulch the wicking pots to reduce water loss from the top and keep a healthy microbial layer at the top of the soil profile (zone 3).
Depending on the time of year, the size of your reservoir and what you are growing, I would comfortably say that this methods halves the time needed to water and also greatly increases the yield of my fruit and veggies.
Be creative - above is a large passionfruit vine growing from a cheap silicone bucket.