Insectary Plants in the Garden: More Than Meets the Eye

Flowering plants don’t just look pretty – they can also do some serious garden work. Beautiful, aromatic blossoms attract beneficial insects – such as pollinators – to the garden. And in vegetable gardens, you can enlist flowering plants to help with pest control, either attracting predators that keep populations of damaging insects down, or repelling pesky insects themselves.

Plants that attract or support friendly insects are called “insectary” plants. And when you plant an area specifically for attracting, feeding, and sheltering insects – such as a pollinator garden – it’s called an insectary planting. By some reports, insectary plantings can increase beneficial insect populations tenfold.

Consider the following plants to beautify your space – and to welcome the beneficial insects that serve as essential workers in the yard and garden.

Bachelor’s button (cornflower) attracts ladybugs, lacewings, and wasps – all effective predators of aphids. These predator insects also consume caterpillars, mealybugs, and mites. Many other members of the Asteracaea family are just as effective, inviting beneficial insets by producing plenty of pollen and beautiful, attractive flowers. Aster, cosmos, sunflowers, and blanket flowers (gaillardia) all make gorgeous, useful additions to a garden.

Lavender can be a workhorse in the garden – and a beautiful one to boot. Its tiny, aromatic blossoms feed beneficial insects, attracting honeybees, bumblebees, and other beneficial insects – as well as having many culinary, medicinal, and household uses. Lavender doesn’t do well in regular garden soil, so you often see it in drier beds or borders, often among other Mediterranean herbs.

Or consider lavender’s siblings in the mint family (Lamiacaea), such as basil, lemon balm, catnip, oregano, peppermint, or sage. If you allow them to flower rather than cutting them back, they’ll produce spikes of blue or purple flowers that invite beneficials to your yard.

Speaking of plants that you may already have in your garden – such as carrot, parsley, cilantro, and dill – these members of the Apicaea or Umbelliferae family can also serve as very effective insectary plants. Their umbels of miniature flowers produce attractive aromas and lots of pollen and nectar for small beneficial insects. These tall, stalky plants – once they bolt – also offer perfect habitats for helpful predator insects.

Sweet alyssum, with its low masses of tiny white blossoms, grows quickly in areas of part shade, making it ideal for planting among vegetables. Alyssum is highly attractive for predator insects – including lacewings, which feed on alyssum nectar and pollen and then lay their eggs on the plant. The lacewing larvae go on to eat aphids – each of them can consume up to 100 aphids per day. Alyssum makes an especially good companion for onions, as it also helps control onion thrips.

These flowering plants are insect magnets (much like me). But there are also attractive plants that repel unwanted insects, by producing essential oils that act as natural insect repellents. They won’t completely rid your garden or yard of pests, but they can make a difference.

Calendula, also called pot marigold, might be the most well known of the insect-repelling flowering plants. Calendula both attracts beneficial insects and repels unwanted ones – including asparagus beetles, aphids, whiteflies, and mosquitoes. It’s even said to deter rabbits. Normally, pot marigolds are kept as an annual, but if allowed to grow a second year, their roots will begin to repel nematodes.

Alliums – from low-growing chives to leeks and shallots, all the way to the huge Allium giganteum – will drive away slugs, aphids, Japanese beetles, carrot flies, and cabbage worms. Plant them throughout the garden, especially near tomatoes, peppers, cabbage, broccoli, and carrots.

All kinds of cole crops will benefit from the presence of lovely hyssop. Its fragrant purple spikes are said to repel cabbage moths, white butterflies, flea beetles, and slugs – while attracting lots of helpful bees.

Nasturtiums have long been well loved as companion plants, especially as an edging for vegetable gardens. They will protect tomatoes, cucumbers, radishes, kale, collards, broccoli, and cabbage from whiteflies, squash bugs, aphids, cabbage loopers, and many kind of beetle.

Chrysanthemums are the natural source for pyrethrum, a common ingredient in commercial bug sprays and pet shampoos. Plant chrysanthemums for use as a cut flower and to control roaches, ants, Japanese beetles, harlequin bugs, root-knot nematodes, and even ticks, lice, and fleas. But please don’t attempt concoct your own insecticidal spray from chrysanthemums – or be very careful if you do! Concentrated pyrethrum is toxic to humans as well as insects, and can cause problems ranging from skin irritation to nausea and unconsciousness. The small amounts found naturally in the flowers won’t hurt you – in fact, the flower petals make a pretty garnish for a salad, and can be used as a substitute for saffron.

Borage’s small, vibrant blue, nodding flowers accent a sprawling plant with soft, fuzzy leaves. Borage repels tomato hornworms, while attracting pollinator bees. Planted near tomatoes, borage will not only help protect the tomatoes but even improve their flavor.

Insectary plants are most helpful when you plant a variety – the different shapes and sizes of flowers will attract and feed different types of insects, and varying blossoming times will ensure nectar, pollen – and color – throughout the season. So don’t hold back when you add these beautiful plants to your garden – the insects will thank you. And you’ll be rewarded with a colorful, healthier garden.