I've read about "nurse crops" intended to provide shade for slower-germinating crops, and then provide a "scaffold" for the other crop to cling to so it can reach the sun. Oats will sprout quickly, then legumes can sprout in their shade, and crawl up their stemss.
Also, a guardian plant (“trap plant") may lure pests away from more valuable plants: like planting lettuce near Delphiniums in the hope that slugs will prefer the lettuce. Eggplants may lure whiteflies away from poinsettias.
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http://www.ballpublishing.com/...
Using Plants to Fight Pests
| by Deborah O'Connell
The above is a "beefy", detailed article with reference links and case studies.
(quote)
“We call plants that help manage pests in the greenhouse ‘guardian plants’ because they help to guard the grower’s crops against pest damage,”
...
Some guardian plants attract pests away from the crop and are called ‘indicator’ or ‘trap’ plants.
Other guardian plants attract natural enemies by offering food such as pollen or nectar and are referred to as ‘habitat’ plants.
Still other plants support insects that serve as food for natural enemies. These are called ‘banker’ plants.”
(end quote)
The thread "Companion success stories" in
Companion Planting forum
In the above thread, Stephanietx listed some links about "companion planting", where planting one plant near another helps one of them out, for example the "Three Sisters" combo of corn, beans and squash.
(quote)
Here are some helpful companion planting sites I've found.
http://www.ghorganics.com/page...
http://www.gardenguides.com/41......
http://www.reneesgarden.com/ar...
http://luv2garden.com/
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