I have shared this paragraph in the course notes citing your good work: Keith Mikkelson
1-5 Ref- Companions
Companion planting is also called inter cropping. These crops are used for insect control, to make wind blocks, and they promote soil conservation. When harvested, they are used for compost and feed for livestock. Companion plants also create a desirable mulch and green fertilizer. Under sowing is a very popular means of companion planting also.
Some plants give benefits that help others grow. Tomatoes do well with carrots because the carrots stimulate the growth of tomatoes. Others, like marigold, ward off certain insects. Onions prevent the carrot fly from infesting the root with eggs. Papaya wards off corn pests like the stem borer.
S.A.L.T. hedges [Sloping Agricultural Land Technology] prevent high winds from damaging crops that are planted between rows and filter the wind while preventing erosion. The hedges that make good companions in our system are usually legumes, but any plant can work. Plant rows following the contour of the land and make every other row a different crop. Use the hedge trimmings as mulch, animal feed, compost or green fertilizer.
There is a huge range of opinions on which plants help or hurt each other. Some of the results are not always worth the effort, but I included some combinations that work for us. Sharp eyes and good notes help you learn what is going to work on your soil and climate with the crops you decide to grow.
According to Advanced Home Gardening by Miranda Smith, dill attracts small beneficials, but inhibits carrot. Mexican bean beetles won’t be a pest when you plant petunia with beans. Bush beans inhibit onions but are good with carrots, cauliflower, beets, cucumbers, and cabbage. Some work remarkably well, while others are only seasonal solutions.
Broccoli and cabbage are commonly planted with celery, chamomile, sage, beets, onions, and potatoes. Onions repel the carrot fly, so onions and carrots grow well together. Fennel inhibits many species of plants and has no companions. Plant it alone. Garlic repels aphids. Nematodes won’t wreak havoc when there are lots of marigolds. Marigolds are our favorite weeds now.
Small Beneficials are attracted to parsley; Miranda recommends that you interplant with carrot or rose. Some companions hinder other plants. Sunflowers inhibit nitrogen-fixing bacteria. All the intercrop guides boast that Stinging Nettle will attract small beneficials. They claim almost all plants benefit from it. We don’t have it here in the Philippines but it is a North American weed.
Here are a few suggestions from the Philippines. In Practical Guide To Organic Gardening by Pedro D. Sangatanan & Rone L. Sangatanan, they recommend celery with cabbage to protect from the cabbage butterfly. Garlic among your tomatoes and potatoes will prevent blight. Marigolds with beans repel the bean beetle. Radishes with cucumber minimize damage from the cucumber beetle.
At Aloha House we have stumbled on some of the most effective companions by mistake. One time we planted broccoli among some sweet basil seedlings just to use up the space (that alone is a good reason to inter crop), and found total protection from the caterpillar (cabbage moth) that would usually destroy broccoli when un-netted.
Papaya wards off some of the borers in sweet corn so we started planting lots of them. Papaya trees are all over the place. We have enough for all the babies in the orphanage and we never tire of this great fruit! We now under sow it with a legume like mongo bean or perennial peanuts and it really benefits from the free fertilizer these powerful legumes produce in the root zone.