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More plants, better gardens |

More plants, better gardens

Jessica Walliser
Incorporating flowering herbs like dill and oregano into the vegetable garden is one way to boost plant diversity in your landscape.

Increasing the amount of plant diversity in your landscape is a giant step toward creating a more self-sustaining, less-chemical-dependent garden. Plus, a greater variety of plants leads to an increase in the number of birds, amphibians, pollinators and beneficial insects your garden is able to support.

Because of this increase in “good” creatures, a decrease in pest numbers often follows. Not to mention all the beauty found in a garden filled with a broad diversity of plants. Here are a few simple ways to pump up the plant diversity in your backyard.

Interplanting: Long rows or blocks of the same kind of plant are easily discovered by pests, especially in the vegetable garden. But when you mix it up and intermingle a broad assortment of plants, pest densities are reduced. Interplanting involves growing several different plant species together to increase diversity, build corridors for wildlife, and create favorable habitat. It also adds different nectar and pollen sources to the garden. Interplanting can involve simply alternating crop rows in the vegetable garden or, better still, mixing flowers into shrub beds and foundation plantings.

Under-planting: Another way to build garden diversity, under-planting is done by planting a low-growing plant underneath a higher-growing one. For example, under-plant your tomatoes with a mixture of lettuce and sweet alyssum. The tomatoes shade the lettuce from the summer sun, while the alyssum lures in the parasitic wasps that control the aphids on the lettuce and tomatoes.

In my own garden, I get higher yields because I am making good use of all the available space, and I have fewer weeds because the alyssum and lettuce form a living mulch beneath the tomatoes. Or, interplant rows of peppers and eggplants with rows of dill and coriander to deter pests and introduce beneficial insects. Mix lots of flowers into the vegetable garden as well as into shrub areas and tree islands.

Plant sunflowers: Sunflowers are as useful as they are pretty, and including them in your garden is a great idea. Sunflowers produce extra-floral nectar in addition to floral nectar. This extra-floral nectar is produced from the leaf undersides and serves as a carbohydrate source for ladybugs, parasitic wasps and other pest-eating beneficial insects. Researchers have noted an increase in the population levels of various predaceous beneficial insects when sunflowers reach a mere 6 inches in height. Planting sunflowers within rows of vegetables is an effective way to help battle pests and increase diversity in the garden.

Herbs in the vegetable garden: An integrated vegetable garden — one that incorporates an array of flowering plants with the vegetables themselves — is another excellent way to diversify the garden. It’s also quite beautiful. Not only can the herbs be readily harvested for kitchen use, but also, later in the season, when they are left to flower, they’ll provide beneficials and pollinators with nectar and pollen.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is

Send your gardening or landscaping questions to [email protected] or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.

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