Benefits of Companion Planting
Host Finding Disruption
This type of companion planting seeks to confuse or ‘disrupt’ the insects from locating the host or your vegetable plants. Scientists studied the pattern that insects use to find the host on which they wish to feed.
They are attracted to the scent of the host plant. If you have ever stepped into a greenhouse with thriving tomato plants you have experienced the sensation that these insects do. The insect avoids landing on bare soil, there are predators there that can kill them. So they land on the first ‘green’ thing they can locate.
From there, the insect begins hopping from leaf to leaf searching for the perfect perch on which to feast. According to studies done, if the insect cannot find a suitable location on something ‘green’ they will give up and fly away. What the scientists did was add clover to the equation, giving multiple ‘green’ targets for the insect to land on.
Clover as ground cover around cabbage gives the cabbage root fly more ‘green’ to plant eggs near. The emerging larvae crawl around to find only clover. The study showed that thirty six percent of the insects laid eggs next to the cabbage when bare soil was used, versus seven percent when clover was planted next to the cabbages.
The scientists also made decoys of green cardboard that also disrupted the insects patterns of landing and discouraged them from staying and feasting.
Pest Suppression
Some plants give off a natural pesticide that repels insects, some repel weeds, while others repel nematodes and fungi. These natural solutions to pest suppression can help keep the man made chemicals from touching your garden while still keeping them healthy. You just have to know which plants to place where.
Pollinator Recruitment
Without bees, it is said that the Earth would begin to slowly die out. Bees pollinate the fruit and vegetables we eat, without fruit and vegetables, large animal populations would die off. Without large animal populations, herds of cattle and pigs would starve. Eventually that would work into the food chain leading to humans.
Since bees, as well as other beneficial pollinators are so essential to the survival of the Earth itself, think of the impact they will have in your garden.
The chemical means to keep the tomato beetle and aphids from your harvest will kill those insects that are helping your garden thrive! Chemical pesticides do not discriminate. There are plants, though sometimes these plants are not vegetables or fruits that will attract these busy garden workers to your garden. Planting a few of these nearby will allow them to do their work.
Predator Recruitment
While some insects help your garden through pollination, others will help by preying on the pests that wreck your garden. Some of these ‘predatory insects’ eat pests, others lay eggs on the bodies of pests, while still others lay eggs near the plant where their larvae will hatch and feast on the nasty bugs. We will discuss a few of these so you can plan your garden in detail before ever planting a seed or turning the soil.
Aphids are the bane of the rose garden. But they can also do substantial damage to vegetable plants and fruits as well. Planting marigolds near the plants that may attract aphids will help keep them away for two reasons.
Companion planting can also help with obtaining at least a part of a crop despite catastrophic damage to a crop nearby. If the borer worms destroy your lettuce, corn or cabbage plants, the other veggies in the same location may escape total destruction and still provide some fruit for you. The more plants in the same space there are, the greater the odds of harvesting at least one of those crops.
While some insects prefer one type of vegetation over another, some are voracious enough to devour whatever they find. So while the hedged investment gives you maximum use per square foot of garden space, other methods are needed to keep these pests at bay.
Ladybug beetle hunting aphids.
Increased Level Interaction
Also called protective shelter, this is an example of the seven layer forest garden discussed earlier with large trees providing shade and wind buffering for the smaller more susceptible plants. Or the larger plants or trees act as a trellis for vine plants to grow on keeping the fruit or vegetable high off of the ground where it remains vulnerable to many pests.
Nitrogen Fixation
Just as some plants thrive by using the nitrogen in the soil around them, others thrive by giving off nitrogen in the soil around them. When you know which veggie is which, you can pair them together and anticipate a rich harvest of both. The effects of plants on other plants and the effects of plants on weeds is a study called Allelopathy.
Some walnut trees, like the Black Walnut produces an allelochemical known as juglone. There are many crops that are affected detrimentally by this particular naturally occurring chemical. This observation was made thousands of years ago and farmers were urged to avoid planting in fields where large walnut trees grew. See section on Allelopathy for more information.
Positive Hosting
Positive hosting involves planting specific plants that attract the beneficial insects so that they can spread to your garden plants and eliminate the problem pests. These plants serve as a “host” that will eventually be consumed by the beneficial insects. If you have a colony of beneficial insects growing near your garden, you won’t have a need for the chemicals. We will look at a few of these positive hosting plants.
Trap Cropping
Trap cropping involves planting a decoy plant near susceptible vegetables to draw away the destructive insects. These ‘decoy plants’ are then netted and removed when they become infested and are discarded. More decoy plants will be used to replace the ones discarded. One example of this is the use of Nasturtium. These are smaller flowering plants sometimes referred to as ‘watercress’.
Nasturtium attract caterpillars that will also attack lettuce and cabbage plants. The nasturtium plants are located near the patches of lettuces and cabbages thereby reducing the pest damage to the desired plants.
Pattern Disruption
Once one tomato plant has been infested, the monoculture planting method leaves an entire row of plants vulnerable to the infestation of the same bugs. Pattern disruption spaces out the similar plants from each other making a total loss of vegetables or fruits less likely. The key is in what plants to use to disrupt the predator insects typical pattern of infestation.