The Seasons of the Garden: Soil Blocks and Vegetable Gardening Tips

We offer suggestions for growing seedlings and a review of the latest gardening research.

| January/February 1986

Greg and Pat Williams, expert gardeners, share tips and ways to utilize new gardening research.

Our Favorite Method for Growing Seedlings: Soil Blocks

Peat pots, plastic flats, foam cups - we've tried most of the traditional systems for starting seedlings. But last year we experimented with soil blocks, and now you won't find us using any other method! The blocks are easy to make, very inexpensive and they work wonderfully. There are several mail-order sources for the little machines that produce these cubes; a four-blocks-at-a-time model costs under $20 and should last a lifetime. And we've had excellent results using commercial potting soil with our block maker instead of the costly mixes that are "specially formulated" for soil blocks.

We have run into one problem, though: Top watering causes erosion damage to the blocks, no matter what medium we use. You can get around this by using misters, but then you have to water quite frequently.

We think bottom watering is the way to go. Put absorbent cloth under the soil blocks and stick one end of the cloth into a container of water. The material will act as a wick, absorbing moisture and bringing it to the bottom of the blocks.

Our particular arrangement (which, admittedly, is difficult to move) consists of two-inch soil blocks on an old cookie sheet. One end of a thin cloth diaper runs under the blocks, while the other end rests in a waterfilled bread pan that sits just below the cookie sheet. No doubt you could easily make a more attractive and portable unit from scrap wood and plastic cookware. The important point is that a diaper — or similar absorbent cloth — works just as well as the expensive capillary matting sold by horticultural supply houses.

When using cloths for bottom watering, make sure they're wet before you add the soil blocks. And don't let the water containers go dry! You'll probably need to add liquid only once every few days — no more daily watering or hourly misting!

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