Is there a good reason for growing marigolds in a vegetable garden?
Companion planting has long been practiced by organic gardeners looking for natural ways to control insect populations without resorting to pesticides. Marigolds are often grown in vegetable gardens because they enjoy a reputation for repelling a wide variety of bugs as well as acting as a trap crop for harmful nematodes.
There are several different approaches to companion planting. One is to introduce plants into your vegetable garden for the purpose of either distracting or repelling insects that would normally feed on desirable plants. Bok choy is often used to attract flea beetles away from more valuable members of the cabbage family, such as broccoli, cauliflower, and Brussels sprouts. Because flea beetles prefer bok choy to broccoli, they will devour the trap crop and ignore (or at least launch fewer attacks against) the more valuable broccoli plant.
A second approach is to grow two plants with complementary growth patterns and nutritional needs cheek-by-jowl so that they share the space without either crop diminishing the other. Corn and lettuce are a good example of this. As the corn grows, it shields the lettuce from the summer heat, keeping it from bolting. Meanwhile, the lettuce gives you something to harvest while you are waiting for your corn to mature. In effect, you are getting two crops in the amount of space it normally takes to grow one without sacrificing any yields.
Companion planting can also include incorporating plants into your garden that attract “good” insects. Some plants are magnets for beneficial insects and once attracted to the garden, these insects tend to stick around, pollinating flowers and zapping the “bad” bugs. All members of the Umbelliferae family – the family of plants whose flowers look like miniature umbrellas - attract large numbers of beneficial insects including parasitic wasps and predatory flies. This family includes parsley, carrots, dill, parsnips and coriander/cilantro. In order to attract these beneficial insects, the plants need to flower, which for biennials such as carrots and parsnips means leaving them in the garden for a second year – well worth it once you see the effect it has.
Keep in mind that many so-called “weeds” are actually useful plants in disguise. It's worth taking the time to learn which ones are having a positive effect on your garden and which ones are simply draining resources.
If you have any questions or comments, please send them to me at vanessa@gardenmuse.ca.
