Last week, as my students in ecology studied the diversity of plant species in a local ecosystem, it occurred to me that biodiversity is also an important consideration in planning the vegetable garden, that the wise gardener will avoid monoculture (the planting of large expanses of a single crop) in favor of mixed plantings. Instead of “setting the table” for insects and diseases by planting entire beds or rows to a single crop, growing a diverse mix of compatible species within each bed or row should minimize these problems in the garden.

I mentioned this to Marjorie, an expert on such matters, and she placed in my hands a well-used copy of “High-Yield Gardening” (M.B. Hunt and B. Bortz, 1986, Rodale Press). In it I found validation for this thinking in the chapter on interplanting, in which they state that interplanting schemes, through their diversity, “create complex ecosystems that imitate the rich mosaic of nature and therefore encourage spiders, toads, and other valuable insect predators and discourage the spread of crop-specific pests and diseases.”

The vegetable garden as ecosystem – what a grand idea! It brought to mind the family of spiders we found last summer among the snow peas, a web filled with a hundred tiny babies swarming around their mother.

In interplanting, two or more crops are grown at the same time in one bed. While each planting yields less than it would if grown alone, the total yield is greater than would be achieved with monoculture, but only if compatible crops are chosen.

Interplanting combinations should focus on both aboveground and below-ground compatibility. Plants that complement one another in the shape of their top growth will fill the available garden space, leaving no room for weeds to grow. Corn and beans, for example, when grown together, intercept 90 percent of the available sunlight. They are also an ideal couple as far as underground compatibility, since corn is a shallow rooting crop while beans have deeper root systems.

Interplanting schemes also should take nutrient sharing into account, mixing heavy feeders with light feeders. Fortunately, most interplanting schemes designed for sharing of aboveground and underground space also result in efficient nutrient sharing.

Imagine the mosaic of green in garden space shared by interplanted brussels sprouts, parsley and spinach; a bed with plants of peppers, basil and tomato arranged in an alternating pattern; a mixture of radishes, lettuce and peppers filling a bed from edge to edge; or a mixed bed of lettuce and cabbage bordered by trellised peas. Some gardeners go so far as to transplant cabbage seedlings among the strawberries after the berry harvest is done.

Many gardeners are drawn to interplanting as a technique for maximizing the use of garden space, and indeed this is one of the benefits. More important, I think, is the integration of this method of vegetable gardening into the ecological landscape. I keep thinking about those spiders in the snow peas.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to reesermanley@shead.org. Include name, address and telephone number.

Vegetable Combinations for Interplanting

Beans – corn

Corn – squash, melons, cucumbers

Beans – corn – squash, melons, cucumbers

Leeks – carrots

Beans – radishes

Leeks – parsley

Cabbage – chives

Lettuce – carrots – onions

Cabbage – peppers

Lettuce – onions

Cabbage – squash, melons, cucumbers

Lettuce -radishes

Cabbage – tomatoes

Melons – radishes

Cole crops – tomatoes

Onions – cabbage

Corn – cabbage

Onions – peppers

Corn – lettuce

Onions – spinach

Peas on trellis – cole crops, turnips, lettuce, carrots, spinach