You probably thought nothing of it when you planted beans beside your tomatoes last year. But you broke “no-no” rule of gardening: Beans and tomatoes is in opposing biological families. And one has very different requirements from the other.
Sunlight and moisture dominate most gardeners’ minds because that’s what dictates whether or not something will survive right now. But if you don’t heed the plant’s DNA, chances are you won’t make it past mid-summer. Knowing plants’ ancestry alter everything from seed saving to pest management and crop rotation. Twelve of the big plant families common to home gardens is shown on a chart.
Why Plant Families Matter for Your Garden
Why does this matter? Nature has patterns. If a pest gets good at devouring your tomatoes (the nightshade family), then it will have no problem digesting their cousins: potatoes, peppers and other nightshades. They are all signaling to insects what chemical defenses they have so once you let a Colorado potato beetle chomp on a potato, the rest won’t stand a chance.
Planting relatives in the same place over and again is asking for trouble, but it sure makes harvest convenient. You can avoid it through crop rotation, which is based off family classification rather than a vegetable’s name. Moving a crop into a different bed doesn’t work if, say, you have some corn adjacent to a piece of wheat; they’re both grasses and will use up the same nutrient.
Brassicas needs calcium, and legumes help to fix nitrogen, as shown in the chart. Rotation of heavy feeders such as corn with nitrogen-fixing beans lets soil replenish itself. Maybe your grandmother made you rotate crops every three or four years because of that? She was thinking about more than just visible plants… The microbial life in the dirt, too.
Looking beyond leaves helps ID things: structural clues is harder to hide. Carrots and grasses tends to have hollow joints; mints typically have square stems. What’s a flower good for? If it is attracting butterflies or bees (or both), we know what kind of pollinator relationships is taking place in our garden.
Composite heads (the daisy family) are common in many landscapes as they’re a magnet for butterflies and bees, which increases those plants’ rate of pollination, including nearby crop species. Not just pretty; this is functional ecology at work.
That’s how aware we need to be about seed saving, too. Two varieties of zucchini planted side by side don’t make hybrids, unless one is a different species then the other. But when you plant more than one variety in the same family, you must isolate them quite a bit. Otherwise, they’ll cross-pollinate. Your seed won’t match the parents’ variety, though it might yield healthy-looking plants. That kind of messes up an heirloom collection, which is why knowing your families can helps prevent that.
I mean, it makes gardening more like a strategy with less guesswork. Knowing how things relate means you’re no longer working on one plant at a time as if it were a lone issue. Instead, you are thinking about the whole garden as a connected system. What happens here affects other beds; what we do to the soil has consequences.
The next time you get out your trowel, remember that what grows together also grows apart. It’ll make all the difference in your harvest (and your soil). You should of known this earlier. Actually it makes gardening more naturaly fun.