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Growing Vegetables in Containers

If you fall into one of those categories, you may wish to read Ed Smith's new book, "Incredible Vegetables from Self-Watering Containers". You may wish to plan a small garden on the deck this summer, or along the driveway - in pots.

For the past three years Ed Smith, and his wife, Sylvia, have been growing vegetables in self-watering planters, and they have got the art of growing ORGANIC (italics) vegetables in pots down to a science. That's right, organic vegetables, not plants pumped up on liquid chemical fertilizers. You can easily grow plants that produce tomatoes you'll want to eat. The Smiths have tested out everything from artichokes to zucchini and found you can grow just about anything you want in a pot - including sweet corn.

Self watering planters are relatively new on the market - they look like regular pots except that they have hidden water reservoirs in the bottom, and a wicking system. Watering from below provides consistent moisture for plants without leaching out soluble nutrients - the way watering from above does. The water reservoir also makes it much easier to keep big plants from drying out on hot August days when you're at the beach.

Here's what the Smiths do: First, they make plant-friendly organic potting soil. The roots of plants in pots need a porous medium in which to grow, a medium that allows water and air to circulate freely. Standard potting mixes are made of peat moss and fluffy, inert ingredients like vermiculite or perlite. In Ed's system those same ingredients make up about 50 percent of the mix, but good bagged compost makes up the other half. The compost provides nutrients that a chemical fertilizer just doesn't offer, and encourages beneficial microorganisms to nurture the plants as they would in your garden.

In each 40-quart batch of planting mix the Smiths add 1/3 cup of each of the following ingredients: dried blood meal for nitrogen, greens for potassium and trace minerals, and colloidal phosphate for phosphorus. They also add a tablespoon of Azomite, a commercially available mixture of raw trace minerals, though that is not essential. All the ingredients are approved for use by organic gardeners.

Ed and Sylvia live in Marshfield, Vermont, but came to visit me in Cornish Flat recently to talk about gardens - and to eat some of my squash and peanut butter soup. Ed explained that a tomato plant requires about a gallon of water per day in August for optimal growth. For most planters, that would be impossible to give all at once - the water would just run through the pot. The reservoir of a large self-watering planter, however, can hold 2-4 gallons of water, which gives busy gardeners some leeway.

Growth stops each time the soil dries out completely. Plants have no heart to pump water and nutrients from the ground to supply stems and leaves. Instead, transpirational pull caused by evaporation of water from leaves moves the essentials around the plant. But if there is no moisture to replace water lost to evaporation, everything stops. It's as if the heart has stopped. "By the time a plant starts to wilt, there has been a serious growth interruption - one from which the plant may not recover fully," according to Ed.

Ed and Sylvia explained that there is essentially no weeding required for plants in pots. Properly made compost should have no viable weed seeds, nor does peat moss. Although a few blow seeds could, in theory, get blown in, the Smiths say weeds have never been an issue for them.

What about pests? Most plant scientists agree that stressed out plants send out signals that are like welcome mats for insects. Since their never dry out and have an adequate supply of slow-release organic nutrients, they aren't stressed. Ed also pointed out that, "Much of your container garden may be in places where insect pests wouldn't think to look for a meal."

Soil borne diseases are rare, too. Some of those diseases (such as fusarium wilt that causes the premature blackening of leaves on tomatoes) can live in the soil for up to 10 years, causing problems year after year. But since there is no actual soil in the planters, and peat moss and cured compost should have no disease organisms, potted plants may do better than their in-ground brothers.

Self watering containers can cost $25 or more, so I asked Sylvia what she would grow if she could only afford three. In one 40-quart planter she would squeeze in two tomato plants. Next she buy a large hanging self-watering planter and plant 6 herbs in it -some erect (such as basil), some, like prostrate rosemary or thyme, hanging over the edges. Lastly she would choose a self-watering window box for cut-and-come-again lettuces of all sorts, planted close together. That sounds like a pretty nice garden to me.

Henry Homeyer is the VT/NH associate editor of People, Places and Plants magazine. His website is www.gardening-guy.com.