A Brief History of Gardening in Containers:
Do you like gardening but digging in the dirt is too painful, messy, or time consuming? Container gardening is your answer. For many years now, container gardeners have been using pots, tubs, and boxes of all sizes to garden in. While raised bed gardens have also gained in popularity, so have "bucket gardens" or tubs become an economical way to garden with more control over your soil and more success with hard to grow vegetables.
Recently, the advent of so-called "self watering" containers have helped gardeners to grow flowers, vegetables, and herbs with even more success. Many companies, such as Earth Box, The Grow Box, and models from Gardeners Supply and others have developed easy to assemble boxes with water reservoirs in the bottom. However, these are often pricey. All over gardening websites and forums, do it yourself versions of these boxes have popped up to provide more economical ways of yielding the same results with significantly reduced costs. There is even a book on gardening vegetables in Self-watering containers by Ed Smith, which you can find here.
At the University of Maryland Extension, Jon Traunfeld designed a Salad Table which is essentially a shallow wooden frame with a large surface area and a mesh bottom that allows water to drain. This is a design of great benefit, as you can plant seeds and cut vegetables comfortably at waist level and avoid problems with pests on the ground. If you would like to know more about Jon's original table (and find many more uses, ideas, and advice about Salad Tables), please visit his page here.
I loved the idea of a salad table as a way to maximize the space I have to grow salad greens to feed myself and my rabbits. Having made my own self-watering tubs for lettuces and other greens the previous summer, I saw how well they flourished with this method even under the hot humid summers of Washington DC. So I decided to combine both the ideas of self-watering containers and the salad table into one. The result is this instructable. This table is deeper than a 2X4, so you can grow much more than just salad greens in it, as you have more space for roots.
What is Self-Watering?
Essentially, this is a system where by you allow water at the bottom of the container to be drawn up, or wicked, to the roots as they need it. There is an overflow hole in the side of the container, near the top of the water reservoir that overflows when the water reaches the top. For me, the term self-watering is a bit tricky as you still have to water the vegetables, you're just doing it from the bottom of the container. This allows the plant to draw water as it needs it, thus reducing the possibility of overwatering or underwatering. The holes in a wicking basket or chamber allow the soil to touch the water for wicking. For tricky or picky vegetables, this also allows you to maintain an even level of moisture in the plant which is what many of them need to grow well.