Now onto the questions -- I think I might like to add wicks to the pots, especially early on in the season when the plants are small. But, my understanding is that the wicks need to actually dangle downwards from the bottoms of the pots. Is this correct? It really wouldn't be practical to elevate these large pots and they wouldn't be as stable if I did so.

Can I just just drill a hole in the side of the pots a couple of inches from the bottom and insert the wick there? Or could it just be inserted in one of the multiple drain holes at the very bottom of the pot and just allowed to lay on the ground?

The wick works via a process known as capilary action. Vertical orientation is not required for capilary action. Capilary action is based upon the principle that where one molecule goes, others will follow. So, if one water molecule travels along the wick, other water molecules will be pulled, via capilary action, along with it. Up, down or horizontal makes no difference.

Now, with a single wick in a very large pot this may or may not work well for you as a watering device. The trouble is that capilary action may not wet the soil as quickly as it is used up by the plant and evaporation. You might consider rather thick wicks and using more than one for a 20-30 gal pot. Also, try to minimize the amount of wick that is exposed to the air as this also results in rapid evaporation.

As far as placement, I would not suggest allowing the wick to touch the ground, otherwise the water will leave the wick at that point. The idea is we don't want anything removing water from the wick other than the potting soil.

If your issue is providing enough water to your plants I recommend you think about a small scale automated drip irrigation system such as can be purchased from The Drip Store

All you really need is a timer, a hose from your outdoor faucet to the general area of your pots and some thin soaker hose to wrap around the inside of your pots. Spend around $75 one time and never water a pot again.

As far as placement, I would not suggest allowing the wick to touch the ground, otherwise the water will leave the wick at that point. The idea is we don't want anything removing water from the wick other than the potting soil.

Ah, but that's exactly what I -do- want.

I see I need to clarify -- the wick is not to be used for watering at all, but to enhance and give me more control over drainage (especially when the plants are little), i.e. extend the PWT (perched water table) as Tapla has referred to it.

Now, in the thread "Container soils and water in containers (long post)" where this is discussed, I'm not completely clear on whether Al is saying that the container -must- be elevated somewhat in order to get the effect of effectively wicking -outward-. Hoping that this is not the case, looking for clarification...

Here is a link that might be useful: that thread about wicking

To take best advantage of wicking, your container should be somewhere where the water will be moved away from the bottom surface of the container. What fits the bill best is elevating the containers and leaving a portion of the wick to dangle, or setting the container on soil that will drain water away. Since wicking makes water react as if the container is deeper than it really is, most of the water in the perched water table moves downward and out of the pot.

Capillary action is not so simple as one molecule following another. That is part of it and represents the cohesion part of the formula. Cohesion is waters tendency to want to stick to itself. The other two primary consideration is adhesion, which is waters tendency to stick to other objects (soil particles) and the effects of gravity.

The statement "Vertical orientation is not required for capilary (sic) action" is true, but for the purpose of wicking, vertical orientation of the wick allows us to enlist the aid of gravity, where horizontal orientation does not. You can wick effectively if all you have is holes at the bottom sides of the container by allowing the ends of the wicks to dangle or contact soil under container. The wick will be more effective if it contacts soil rather than grass or other vegetative tissues because the capillary pull of soil is stronger.

Did that resolve your question, Suze?

Al

Several years ago I got tired of having to water my potted tomato plants twice a day and began developing self-watering pots.

What I used this last summer worked well up to the point a heat wave occurred in the Pacific Northwest with a month of tenpertures in the upper eighties, and over ninety at times. Found I had to hand water every day to keep things alive. I only grow small bushy plants these days. Used grow such plants as Early Girl but don't like tomato plants that stretch out with a tomsto here and there anymore. Glacer is now my favorite tomato and in every way. It provides many clusters of up a half dozen medium small tomatoes that are strong in tomato flavor and sweet.

The set-up I used this summer was made with inexpensive food-grade five gallon buckets from Walmart for the reservoir and much smaller mop buckets also from Walmart for the soil. These fit into the larger buckets perfectly, and extended halfway down inside the five gallon buckets A two inch or a little lsrger hole was bored into the side of the larger reservoir buckets to serve as both filler holes as well as overflow holes. These holes were positioned just below the bottom of the inside buckets. In the button of the smaller inside buckets four one inch holes were drilled toward the sides of the inner buckets for the purpose of running wicks through them. For the wicks I used torn kitchen fabric toweling ripped into four by twelve inch sizes. These I rolled up and positioned them extending up through the holes as to reach about four inches through thr potting soil when it would be added to the pot. The lower ends of the wicks were wrapped in black trash bag plastic so the wicks would not be drying out as the water in the reservoir lowered. The bottom of the wicks reached sll the way down to the bottom of the big bucket. The reservoir bucket.

For potting soil I used Miacle Grow as I had found it pulls the water from the wicks really well and draws it all the way to the top of the pot. Had found that various other potting mixtures I tried did not work at all. I started the wicking process by well watering the soil from the top. I used finely powdered water soluble plant food made for for tomatoes, adding it in through the filler hole. Though I also spread some on the soil's surface before I watered the pot from the top. I was concerned that the plant food might not get wicked, but it did.

For next year I am going to switch out the wick materisl I used for purely synthetic stuff, and add more wicks. Tomatoes are thirsty things. Oh, I also added wireframe tomato towers to the pots (ultra necessary) and I plan to incorporate heavy duty clear plastic tents next year too. Those I have yet to make.

It is a lot of work to grow tomatoes but I do it because they are my favorite vegetable and the ones they have in the supermarkets here in the Pacific Northwest are shipped from California and are grown for best shipping making them flavorless and rock hard.

Late to this thread, but around the time this thread was created, I bought Blumat ceramic wicks from Amazon since I couldn't keep up with the daily or bi-daily watering requirements during the summer heat. They work really great and life has been much easier.