There is no rule that states vegetables and flowers can't mix. In fact, a vegetable garden benefits greatly from the addition of flowers and herbs. But it's not just aesthetics that make flowering plants welcome in the vegetable garden.
Companion planting flowers and herbs with vegetables offers several beneficial features that can protect your vegetables from insect pests and may even make them more productive.
They Act as Trap Crops
If you can't repel a pest, plant a sacrificial plant to attract them. This is often accomplished with another vegetable crop, such as surrounding cabbage with a trap crop (or catch crop) of collards to attract the diamondback moth.
The pest insect will congregate on the trap crop, which you can then hand pick and destroy. The most famous flower trap crop is probably nasturtiums, which attract aphids. Nicotiana is also a viable trap crop. Chervil keeps slugs away from your leafy greens, and mustard attracts lygus bugs (tarnish bugs) to keep them away from your apples and strawberries.
Before you plant trap crops, weigh the risk of attracting more of the pest to your garden than before. The trap crop technique is generally used the year after a pest has done significant damage to your plants. If you can, time it so that the trap crop is more mature than the plant it's protecting.
They Attract Pollinators
Vegetables don't always have the showiest flowers. To make sure bees and other pollinators can find your vegetable plants, companion plant flowers with high nectar concentrations or in shades of blue, yellow, or white. And, don't overlook flowering herbs.
Herbs in the mint family, such as oregano and thyme, are particular favorites of bees. Of course, you will have to stop harvesting a few plants to give them time to set buds and flower. Some additional choices include cosmos, larkspur, mints (watch for invasiveness or plant in a container), sunflowers, sweet peas, and zinnias.
They Attract Beneficial Insects
Most insects are not garden pests, and some insects prey on the actual pests. These beneficial include insects such as ladybugs, lacewings, parasitic wasps, and ground beetles.
As with every other insect, beneficial insects have certain preferences in plants. Companion-plant their favorites, and you'll eventually have beneficial insects patrolling to consume your bad insects. Parsley, dill, coriander, and flowers from the aster family are especially good for attracting beneficial insects.
They Repel Garden Pests
It is still questionable whether some plants actually repel garden pests or just make for a healthier ecosystem. But the topic is worth further study, and it sure can't hurt to try some of these companion pairings if you have a problem in your garden:
- Anise hyssop to repel cabbage moths
- Borage to repel tomato hornworm
- Catmint to repel aphids, Colorado potato beetles, and squash bugs (verify if it is invasive in your area; it's a fast-grower)
- Geraniums (Pelargonium) to repel Japanese beetles
- Pot marigolds to repel asparagus beetles
- Sage to repel cabbage moths and carrot rust flies
They Promote Biodiversity
What all this companion planting is leading to is the concept of biodiversity, or planting a wide variety of plants rather than a single monocrop. Diversity helps to confuse insect pests by planting things they love with things they won't touch as well as to attract beneficial insects that can keep pests in check. Whether there is also a symbiotic relationship between different plant species is still being studied.
You Can Hide the Cutting Garden
One final bonus of companion planting flowers in the vegetable garden is the ability to place your cutting garden where it won't be judged for its design or appearance. If you want to plant black-eyed Susan, celosia, salvia, and zinnias in straight rows that will always be halfway cut down, plant them among the vegetables where looks don't count as much as function. Let them do dual duty as cut flowers and pollinator lures.
Companion planting vegetables, herbs, and flowers is how the original cottage garden style evolved. Sectioning off gardens for specific types of plants was a luxury of the rich.
Besides all of the benefits outlined above, if you are short on space or time, companion planting could be the answer to some gardening dilemmas.