Check out this chart on Companion Planting. Click the image for the full version.
Here’s when I started believing in companion planting: in 2005, I planted an oregano plant. It started to have problems right away, drooping and looking sad. I watered it and waited, but the plant got worse.
Then I read that chives are a good companion plant for oregano, so I put some in the same planter as the sad oregano plant. Within 24 hours, the oregano perked up and began to flourish. It even grew into the space that the chives took up, as if to hug it.
I still have both plants now, 8 years later. They are remarkably healthy. The oregano has spread under my lemon bushes and the chives–which is very old for a chive plant–is amazingly sweet and tasty. I think their health has something to do with planting the two together when I first got them.
Companion planting makes sense when you think of how plants work in nature. In a forest, you see a mix of many types of plants, not a row of just one type. In a video on companion planting, a gardener explains:
Plants can’t get up and walk away. If they don’t like their environment, many plants do the next best thing and alter their environment chemically, physically, and biologically. When a plant does this, there are other species that benefit from the environmental alteration or are discouraged by it.
Watch the rest of the video here:
The bottom line is that it matters which plants you put together. Sometimes this has to do with chemical alterations in the soil. Sometimes it has to do with root depth of the different plants. And sometimes it has to do with a common pest.
For example, I made a huge mistake this year planting beets and spinach together. Turns out there’s a special leafminer that loves to eat these two vegetables, so putting them together insured I would be dealing with that pest all spring.
That’s how you learn, I guess.
For more on Companion Planting, here’s a post on The Three Sisters: Corn, Squash, and Beans.