Sydney NSW, Australia
For your information
26 hours ago
Companion planting can help keep pests away, deter weeds
For many years, Penn State Master Gardeners were cautioned about giving advice about “companion planting,” since most of the information on this topic was based on traditional garden folklore or anecdotal observations. Fortunately, a recent book by Pennsylvania horticulturist Jessica Walliser, “Plant Partners: Science-Based Companion Planting Strategies for the Vegetable Garden,” uses current research studies on companion planting, or “interplanting,” to provide the modern gardener with many practical applications.
Here are a few examples from Walliser of plants in the vegetable garden that can benefit each other.
Natural weed deterrents
Some plants contain substances that inhibit the growth of other plants, a phenomenon known as allelopathy. Most people know this to be true of black walnuts. Cucumbers are also an allelopathic plant. Cucumbers can inhibit growth of weeds and act as a beneficial ground cover under taller vegetables, such as corn, tomatoes and okra. Start the desired vegetables among cucumbers as transplants, not as seeds. Winter rye is another example of a beneficial allelopathic plant. When used as an off-season cover crop, winter rye inhibits the growth of weeds that would otherwise take hold on bare ground during the winter months.
Crops for and against insects
Planting in tandem can also attract beneficial insects and deter pests. Sweet alyssum (Lobularia maritima), an annual with small, white/rose/lavender flowers, helps control aphids by attracting small aphid-eating parasitic wasps and syrphid flies. Sweet alyssum makes an attractive ground cover or border for the vegetable garden (though it declines in very hot weather). And good news for broccoli and cabbage lovers: Interplanting with thyme has been found to discourage cabbage worms and cabbage loopers, which can quickly devour these cole crops.
Companions to repel disease
Powdery mildew, leaf blights and leaf spots are among the most pervasive and dreaded diseases of the vegetable garden. Choosing shorter vegetable plants, such as carrots, beets and bush beans, as companions for taller vegetable plants, such as tomatoes and peppers increases air circulation, which has been found to help keep these diseases at bay. The presence of shorter vegetable plants among taller is better than bare ground, since they prevent infected water from splashing up onto foliage.
Plants supporting plants
Walliser cites a bit of her own research in suggesting plants that can serve as living trellises. As the indigenous people of our area knew, corn is an excellent support for beans. Walliser suggests giving the corn a head start and planting pole beans, which grow vertically. Okra as a support for very petite currant tomatoes is another winning combination.
Walliser’s overall message is to “mix it up,” since growing a diversity of garden plants will ultimately help avoid serious plant and pest issues. “Plant Partners” contains many more researched examples of beneficial companion planting and is available from online booksellers in paperback and Kindle versions.
As the gardening season heats up, remember that Master Gardeners of Lancaster County are available to help answer your gardening questions. Contact us at LancasterMG@psu.edu or 717-394-6851.
Lois Miklas is a Penn State Master Gardener for Lancaster County, and a former area Master Gardener coordinator.
[Master Gardener column] LOIS MIKLAS | FOR LNP | LANCASTERONLINE
Companion_gardening
Global Plant Protection News 
Leave a Reply