Companion Gardening

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By the Mount Lehman Garden Club

Long before the use of chemical fertilizers, farmers and gardeners found that by planting certain plants close to each other  damage from certain insect pests was lessened. Marigolds (not the ornamental French marigolds, but Calendula Officionalis the old fashioned pot marigold) are wonderful companions in the vegetable garden. They repel Asparagus beetle, cabbage moth, corn borer, cucumber beetle, various nematodes, potato beetle and whitefly. Nasturtiums are another great companion plant. They repel aphids, cabbage moth, cucmber beetle, potato beetle and whitefly. Even if they are not totally effective they will certainly help, and have pretty flowers all summer.

The allium family (onions, leeks, garlic and chives) are also very useful, and if we can cut down on insect predation by changing which plants are grown close to each other, why not? They are said to be good against cutworms, mites, potato beetle, whitefly and slugs and snails. Chives are sometimes planted in rose gardens to repel aphids.

The mechanism by which they work is not fully understood, but it is probably no accident that most of the companion plants have aromatic foliage. Perhaps the strong scents confuse the insects looking for their host plant.

Some plants do not do well planted close to each other. The roots may give off substances the are toxic to certain plants.  The classic example is the Black Walnut. The roots give off Juglin, which is toxic to almost every other plant. Other plants will sort of grow within the drip line of the tree, but they do not do well. 

The following is a brief list of planting combinations that work and ones to avoid:

• Beans are good with celery and cucumbers. Avoid onions and fennel
• Beets like bush beans, lettuce, onions and most members of the cabbage family. Avoid pole beans
• Cabbage, celery, dill, onions and tomatoes like each other, but dislike strawberries, tomatoes and pole beans
• Carrots, lettuce, radish, onions and tomatoes are friends, but keep away from dill
• Corn plants prefer to be near pumpkins, peas, beans, cucumbers and potatoes, but keep tomatoes away
• Cucumbers like corn, peas, radishes, beans and sunflowers, but keep aromatic herbs and potatoes at a distance
• Lettuce grows well with onions, but also likes strawberries, carrots, radishes and cucumbers
• Onions can be planted near lettuce, beetroot strawberries, carrots, radishes and cucumbers
• Tomatoes, carrots, onions and parsley are good companions. Basil is said to improve the flavour, but keep cabbage and cauliflower away from them

Another way to use plants to improve the health of what you are growing is to make up a spray. Shred some plant leaves and steep them in hot water for an hour. Strain into a jar and add a few drops of detergent as a wetting agent. Use it as a spray twice, two days apart. Used in this way garlic is a good all around spray against insect and fungal problems. We may have found a use for the dreaded horsetail – used like this it is supposed to be good against slugs. Two for the price of one! Another useful spray is coriander for aphids and spider mites. Rhubarb is thought to be useful against black spot, but be careful, as the leaves contain oxalic acid, a poison.

For more information on these and many other subjects, join a garden club. The Mount Lehman Garden Club usually meets @ 7pm on the 3rd Thursday of the month at the Mount Lehman Community Hall, 6418 Mount Lehman Road.  

For more information call Yvonne at 604-856-0313.

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