Regional Gardening Reports :: National Gardening Association

In the Garden:
Northern & Central Midwest
May, 2009
Regional Report

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Chinese cabbage blossoms are a direct draw for beneficial wasps.

Bring in the Beneficials

With all the talk these days about being "easier" on the earth, many of us are re-thinking our use of pesticides and synthetic fertilizers. The key to growing a successful garden without too much intervention is to help the garden reach an ecological balance.

One of the critical parts of this balance is to have a garden filled with beneficial insects. These insects prey on the pests that cause problems, and a good balance of predator to prey keeps your garden healthy.

So, how do you get these great bugs into your garden? The answer is not purchasing and releasing them into your garden, but rather planting things that attract them. They are out there, but may just need a little prompting to spend time in your garden.

Plant for Nectar and Pollen
First of all, beneficial insects need nectar (carbohydrates) and pollen (protein) from flowering plants in order to have enough energy to search for prey and to reproduce. The more variety, the better a situation for them.

There is actually research showing that some flowers are much better sources of nectar and pollen to sustain beneficial insects than others. An added benefit is that any insects that are attracted to flower pollen will also pollinate fruit and vegetable crops and increase yields.

Here is a rundown of some ornamental plants that are easy to grow and will bring in those garden helpers.

Cornflower. Cornflowers supposedly release nectar from the leaves even when not blooming. The nectar has a very high sugar content that is attractive to flower flies, ladybugs, lacewings and beneficial wasps.

Sweet alyssum. Sweet alyssum, the fragrant edging for flower beds, is fast-growing and weed-smothering, and is highly attractive to aphid-eating flower flies. Commercial growers even used it as a cover crop between rows of vegetables because it brings in so many tiny beneficial wasps that prey on many vegetable pests.

Mustard-family flowers. Any plant in the mustard family is a draw for beneficial wasps. You can tell a member of this family because the flowers have four petals. Let your radishes and Chinese cabbage go to flower and you'll help out your garden. Arugula, mustard, and many of the Chinese greens are also in this family.

Borage. Borage, with its bright blue clusters of edible, cucumber-flavored flowers, is a favorite for green lacewings to lay their eggs. Lacewing larvae make short work of aphids, scale, and other small pests.

Cup plant. Cup plant (Silphium perfoliatum) is a tall native of the prairie whose leaves wrap around stems, forming a deep cup that collects dew and rainwater for beneficial insects and small birds.

Golden marguerite. Golden marguerite is a long-blooming perennial with bright yellow daisies that attract a host of beneficial such as ladybugs, lacewings, flower flies, tachinid flies, and wasps.

Fennel, parsley. Fennel and parsley flowers are attractive to nectar-feeding beneficials, and they are also host plants for the caterpillars of butterflies.

Ornamental grasses. Lastly, ornamental grasses are favorites not only for nectar and pollen, but also for summer shelter and overwintering sites. Research has shown that one square yard of ornamental grass crown can hold more than 1,500 predators such as ground beetles, ladybugs and other predators. Who knew?

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