What is Companion Planting?

Companion planting is the establishment of two or more cultivars in close enough proximity to encourage a beneficial relationship. This can be many things to many people, but they all have the same goals in mind. These goals can include any or all of the following: attract beneficial insects; deter, confuse or target pests; avoid nutrient depletion; prevent pest and disease from overwintering in the soil; or, increasing yield and biodiversity. For an extensive list of plant friends and foes, check out http://www.ghorganics.com/page2.html?=hobby1

Trap Cropping

The first type of companion planting we are going to take a peek at is called trap cropping. In trap cropping, the “trap crop” becomes a lure that is sacrificed for the good of the more desired crop. The most important factors to consider when planning a trap crop are the pest you are trying to trap, the layout of the trap crop in conjunction with the main crop, and timing. Obviously, the pest you are trying to catch is going to determine the crop you plant to act as the trap, so it is vital to research this and chose correctly. The trap crop can be either a more preferred plant species, or can be the same plant species but timed so that it is at the preferred stage of development when the target pest typically emerges. Additionally, you want to make sure the trap crop is approximately 10-20% of the main crop to ensure efficient protection. Examples include, beans planted to attract any worm from tomatoes; radishes planted near carrots to attract wire-worms and root maggots; and, nettles planted to attract early season aphids. Below are a few other pest/ trap crop combinations.

 

Pest Trap Crop
Aphids Nettles (early season)/ Nasturtium
Blackfly Nasturtium
Greenfly Nasturtium
Whitefly Nasturtium
Slugs Chervil/ French Marigold
Thrips French Marigold/ Basil
Flea Beetle Radish
Root Maggot/Fly Radish
Leafhopper Beans/Legumes
Tomato Hornworm Dill/ Lovage/ Beans
Nematodes African Marigolds Tagetes erecta
Cucumber beetle Nasturtium/ Blue Hubbard Squash
Squash vine borer Nasturtium/ Blue Hubbard Squash

 

Although the trap crop is usually worthless after having done its job, higher yields in the desired crop should make up for the loss of the trap crop. If you have had persistent problems with pests on a crop in the past, this is a great organic IPM stratagem. Another concern when using trap crops as a part of your organic IPM is creating breeding grounds for the pests. However, if you have incorporated companion plants there is usually hungry population of beneficial insects ready to chow down on the pest “nursery” and keep it under control. If the trap crop becomes overrun and the beneficial insects cannot keep up you can always remove it and get rid of the pests along with it.

Nurse Cropping

Nurse Cropping is another form of companion planting when you sow one plant directly in a row or in such close proximity that they are “growing up” together, and one is directly benefiting the other. For instance, it is usually beneficial to plant fast germinators with slow germinators. While the slow germinators take their time to break through, the soil may form a crust further preventing the weak germinators from cracking their way into the sunlight. The fix is planting them directly with fast germinators that will crack through the soil and prevent a crust from being formed. Parsnips and carrots being infamously slow to germinate are greatly aided by nurse cropping with the fast and furious radish.

Another nurse cropping technique is where you intermingle tall, full sun loving plants with smaller shade tolerant plants. One such nurse crop is when pole beans, corn and squash vines are planted together. The pole beans climb the corn stalk to reach more sunlight and mature early. As the beans die off and decay, they free up soil nitrogen for the nitrogen hungry corn to utilize through the rest of its growing season. While the beans and corn are doing their thing, the squash vines are suppressing weed growth and their prickly stems are deterring raccoons from feasting on the corn crop.

Intercropping

Intercropping is planting crops in rotating rows or in close enough proximity where they can mutually benefit from each other in an effort to increase yields and promote biodiversity. Biodiversity in your garden is important because crops that occupy different niches are more likely to complement each other because they carry out different functions and use different resources. In other words, they are not in completion. Additionally, a biodiverse garden encourages healthy populations of pollinators and pest predators. The polyculture also confuses and weakens any attempted pest onslaught. When intercropping it is important to keep in mind the following: spatial arrangement, plant density, plant growth pattern and days to maturity. Planting short and long term vegetables together is one popular way to practice intercropping. This could mean planting short season crops such as radish, kohlrabi or lettuce with long season cabbage or tomatoes. The short season crops will be ready for harvest before the long season crops have filled out.

Square Foot Gardening

Square foot gardening can be beneficial to those trying to maximize plant growth in a small area. It begins by dividing the growing area into small square sections. The aim with square foot gardening design is to assist in the planning and creation of small but tightly planted gardens plots. This method is particularly well suited for beginners as it encourages a bit of experimentation with different plants within a single bed. The basics of this method is to start by dividing your garden in to square foot sections. Each section will be used to grow a different kind of plant. The number of plants grown per square depends on the size of the plant. For example, a single tomato may take an entire square section. While strawberry plants could be planted up to four per square, and up to sixteen per square for plants such as radishes. The logic behind using smaller beds is that they are easily adapted, and the gardener can reach the entire grow area without stepping on plants, or soil. Teaming this with companion planting can prevent weeds from establishing, and even reduce the need for pesticides.