I remember my grandma's garden being covered in marigolds. Every where you looked it was marigolds, marigolds, marigolds! From her, I found out that the pretty sunny-coloured flowers would attract insect predators to combat the aphids and that the marigold's pungent smell kept other pests away.
You, like me, might have heard from your green-thumbed grandma that you should plant marigold flowers next to your tomatoes, but did you know that almost any vegetable you could think of has a best friend to make it grow better?
Benefits to companion planting including:
Crop Protection – plant tougher plants that can handle direct sun and winds at the edges of beds to protect more delicate plants that cannot take the harsher conditions.
Positive Hosting – Its hard to blame insect pests for wanting to sample your buffet of vegetable laid out for them but if you include plants that produce a surplus of nectar and pollen, you will attract beneficial insects that can help manage harmful pests.
Trap Cropping/Decoy Plants – By planting distasteful plants, with either pungent smells, prickly leaves or bitter leaves, next to and surrounding tasty plants, you can avoid many pest attacks; there are also plants that aid in masking the odours of insect-desirable veggies.
Shade regulation – (also called Nurse Cropping) plant taller plants around more delicate plants that prefer shady conditions. I started my peas in March and as they grew, I planted cool-loving lettuce seeds under them.
Natural supports – Tall, sturdy plants can provide physical support for lower-growing sprawling or vine crops. The Iroquois call this planting system the Three Sisters, which includes a stalk of corn acts as a pole for the bean vine that uses the corn for support and binds together the threesome, and a sprawling squash plant with large leaves, providing shade to keep weeds at bay and soil moist.
Enriching soil – Legumes (peas, beans, clover, etc) are useful to plant next to, or prior to, nitrogen-greedy plants as they are nitrogen-fixers. Nodules on the legumes have nodules that become infected with bacteria called Rhizobium which converts nitrogen gas and then stores it in the roots of the plant.
Weed suppression – Weeds will take advantage of any bare soil, so plant dense-leaf spreading plants such as broccoli around smaller plants such as arugula and parsley.
Common examples of companion planting:
* Brassicas (mustard family, includes cauliflowers, broccoli and cabbages) grow well when planted with beans, beets, onions, potatoes and of course marigolds. Studies have shown that broccoli as a main crop intercropped with lettuce was shown to be more profitable than either crop alone
* Basil is said to enhance the flavour of tomatoes, while also repelling insects and disease, however this has not been studied fully. However studies have shown that growing basil around 10" apart from tomatoes can increase the yield of tomatoes by 20%
* Beans and peas will improve the growth of many plants, including brassicas, carrots, corn, cucumbers, eggplants, lettuce, radishes and strawberries
* Calendula flower stems exude a sticky substance that attract aphids and acts as a crop trap. Planted next to brassicas, especially broccoli, keeps the aphids off the broccoli
* Plant garlic near your lettuce, as the pungent garlic odour will repel aphids. Lettuce grows well with beans, beets, carrots, cucumbers, onions, strawberries and radishes; if slugs are eating your lettuce, mint will dissuade them. Garlic is also shown to be more effective than fungicides on late potato blight
* Beets are good for adding minerals to the soil once their leaves decay, which have up to 25% magnesium
* Carrots are best planted near beans, lettuce, onions and peas
* Cucumbers grow well with beans, peas, corn, lettuce, onions, sunflowers and nasturtiums; if you plant radishes near the cucumber, it is said they will repel cucumber beetles
* To repel cabbage moths, plant nasturtiums around cabbages
* To improve the growth of cauliflowers, plant beans to nitrogen-fix the soil as cauliflowers are heavy feeders