Btw, I tried to resolve this mystery in one of my other posts on "Container Soils - Water Movement and Retention" and seeking comments from the experienced ones. ----Quote---- Moving on I am thinking of trying out Self watering containers. I was just wondering as to why it works and why the water is not being wicked up infinitely and result in root rot. The reason that I came up with and I would need the the experts confirmation / comments over here is this 1/ A self watering container is constantly sitting above water and after all the soil in the container has just enough moisture, the water keeps on wicked up until PWT levels are reached (an a portion of it may well be inside the pot itself). Now since the soil at the bottom is constantly in water, the roots do not grow into that PWT area and remain above that level for entire life cycle of the annuals (veggies) and they keep on getting the moisture and the air at the precise time that they need. 2/ On the other hand if we were to keep a container already having roots reaching the very bottom of it (the container) in a saucer full of water, because of the PWT the water will get wicked in through the drainage holes and getting the plant over watered since the roots in the PWT area will rot. 3/ Now that would mean that to make a very easy self watering container would be to let the container sit in the water saucer (perhaps an inch deep) and the potting soil will wick water up and also maintain that PWT. In order for roots to not reach the PWT area, we must ensure that the saucer is always full of water. (Ofcourse the container should be deep enough to allow for both PWT space and the enough free soil space for the roots) Am I reasoning it correctly? ----Unquote--- I did get a reply but I am still trying to understand it :) You know a newbie can have trouble understanding everything the experts say....

A typical commercial potting mix would be mostly peat (70-80%), 10% vermiculite, 10% perlite (in the states anyway, not sure about your side of the pond). These work very well in SWCs in terms of wicking water to the surface while not compacting too badly over the season, largely because they aren't top watered. There seem to be a lot of people using SWCs on this forum and they can tell you what ingredients they have used and whether it wicked to the surface enough to keep the fertilizer strip slightly damp, whether it retained excessive amounts of water etc. When I first started with SWCs I just used a commercial, peat based mix and then switched to not using the fertilizer strip at all and then switched to using bark based mixes. I really don't think 80% peat, 20% perlite would steer you too far wrong though I haven't tried it myself. I see you are in the UK, so may I ask what you mean by the term 'compost'? In the states compost means decomposed organic matter, but I have heard folks on your side of the pond use the term more loosely so I want to make sure I am not telling you to avoid something due to a confusion of the material being discussed.

Does your container have any kind of wick to move water from the reservoir to soil? What I have done that seems to work well is water the non-wick containers from the top until it flows from the bottom. In my wicked containers, I fill the reservoir directly via a port. On occassion, I will water from the top on the wicked containers when I have top dressed the soil. Good luck on your self-waterers. You will love them ...and so will your veggies.

Sorry. Didn't make myself clear. What kind and how much fertlizer would be recommended for growing pumpkins in an E-box? The 6-6-6 or 10-10-10 generally recommended for tomatos? Some other kind/amount? Thanks!