Companion planting

The idea of “companion planting” has been around for thousands of years, but many gardeners aren’t sure what it means. The current definition goes something like this:

“Companion planting is the establishment of two or more species in close proximity so that some cultural benefit, such as pest control or increased yield, may be achieved.”

Historically, gardeners have used the information provided by published charts, which were mostly derived from chemistry experiments using plant extracts in the 1930s. But it turns out many of the plant partnerships listed in these “traditional” companion-planting charts don’t actually work well.

In North America, Native Americans developed highly specialized intercropping techniques to grow the “three sisters” — corn, pole beans and squash. The three sisters’ technique works because the crops cooperate rather than compete with each other for light and root space. The corn supports the bean vines, the squash shades out weeds, and the roots of the different plants get along nicely below ground.

Now you probably wonder why I’m going into all this information about growing vegetables…well, it turns out that Using Plants to Manage Pests and Weeds is something you can do in flower gardening.

Some gardeners use companion planting to deter all sorts of pests in their vegetable gardens, but in a recent survey by the University of Illinois, the gardeners who reported the most success with companion planting to discourage pests used a single technique: “growing tons of flowers.”  The most frequently mentioned plants were borage, calendula, dill, sweet alyssum, and herbs such as basil, garlic chives and oregano.

Several scientific studies have confirmed that these and other flowering plants help reduce pest problems, particularly if your garden is troubled by early-season aphids or other small sucking insects, which are primary food sources for hoverfly larvae.

This is an example of how a ‘good bug’ can work for you in your garden:  We’ve all heard that lady bugs (lady beetles) are great to have in your garden because they devour aphids.  But many of us have overlooked their “partner in crime”:  the hoverfly.  Hoverflies are active, early-season aphid predators (before ladybeetles take over later in the season). Scientists have found that hovering in midair requires so much energy that hoverflies tend to stick close to nectar sources, so if you lure them in with the right plants, they’re likely to stay all summer. Cilantro (coriander) and fennel flowers are strong hoverfly attractants, as are Greek oregano, sweet alyssum, and many other herbs and flowers.

You can also use companion planting to draw the attention of birds, which eat a wide variety of garden insects. In a recent study conducted at four organic farms in Florida, sunflowers inter-planted with vegetable crops doubled the number of insect-eating birds that visited the garden plots. The birds used the sunflowers as hunting perches, then hopped down to feed on cabbageworms, grasshoppers and other small insects, including flea beetles.

So within the same garden, by planting different flowers you can attract good bugs or birds to eat pests at all stages of their life cycle!! 

Could there be an easier, more beautiful way to reduce pest problems before they start?

Finally, another benefit of successful plant combinations, is using them to keep weeds under control.

Have you ever heard of a TRAP CROP?  It is defined as “a plant that attracts agricultural pests, usually insects, away from nearby crops”.  This form of companion planting can save the main crop from decimation by pests without the use of pesticides.  This is often use in organic crop farming, but you can apply this to your landscape and flowerbeds–….maybe planting certain plants on the outskirts of our property to stop the pests from going any further (or at least slowing them down!).

In a perennial bed, we can use this same concept—a low ground cover can smother weeds among taller perennials.  We also use either annuals or strategically placed perennials with our bulbs so that when the flower is gone we can hide the fading foliage with a plant that is in front of it—  because remember –we don’t want to cut back the foliage of these bulbs (because that’s how  the bulb absorbs energy for next year’s flowers.)

Another way you can companion plant is put vegetables or herbs among your flowers.

Eggplant, Okra—these are examples of attractive plants that produce for you among the perennials.  Lettuce, red or green leaf, can be used in container plantings, and low growing thyme can creep around other herbs or flowers in your garden.  These not only look pretty together but have the benefits of keeping pests under control.

Of course, you cannot keep good bugs if you apply pesticides – you have to put away that spray bottle and let them do their job!  By the way, Jonker’s Garden Center is a good place to pick up Lady Beetles or Praying Mantis eggs, and of course the plants we have mentioned to attract these good bugs.

Planting things that flower at different times will provide enough nectar for your ‘good bugs’ all season long, and hopefully you will have less weeds, less bugs AND a beautiful garden of flowers!