by Phil Nauta, The Smiling Gardener
Increasing biodiversity is one of the most important goals in the garden. The benefits are a really big deal, including:
- Decreased disease and insect predators
- Increased beneficial insects and other organisms
- Decreased weeds
- Improved soil fertility
- Healthier plants
- Higher overall yields from the vegetable garden
To get there, we need to encourage more species of plants, animals and beneficial microorganisms all hanging out together.
The microorganisms (bacteria, fungi and protists) and animals (insects, worms, spiders, etc.) can be introduced with quality compost and leaf mulch, two of the most important inputs in most gardens. Compost tea and other microbial inoculants are also increasingly popular to increase microbial diversity.
Then we introduce seeds, seedlings, and plants from the garden center. Since the focus today is on increasing biodiversity, that means companion planting.
While companion planting has its share of mythology - check out my companion planting chart - the general concept is incredibly important.
Some plants create substances that attract or repel certain plant predators. Others create substances that enhance or hinder the growth of other plants.
For example, while I was eating rice for breakfast this morning I was reminded of a huge study 10 years ago on many thousands of acres in China. They increased rice yield by 89% and decreased rice blast disease by 94%, simply by planting more than one species of rice together in the fields.
And that's probably about the simplest form of companion planting there is, using 2 cultivars from the same species. In the garden, we have an opportunity to promote much more biodiversity than that.
Two Easy Ways to Use Companion Planting in Your Garden
There are many books out there that outline which plants should and shouldn't be planted together. I'll just list 2 of the simple guidelines I tend to follow without really even thinking about it:
1. Herbs. Many herbs - including basil, parsley, oregano, thyme, sage and dill - provide many pest control services, so I use them all over the place. Basil is very beneficial, especially when planted with tomatoes and peppers. You do need to do a little research before planting, though. For example, it's generally agreed that you shouldn't plant dill beside tomatoes.
2. Alliums. Onions and many other alliums such as chives and shallots are great all over the place. Onions can help decrease disease on strawberries, but aren't great companions of legumes. Garlic is a member of the same family, and is another one that should be used liberally.
Then there are polycultures, which in its simplest form just means planting a bunch of plants in close proximity in order to allow them to benefit each other and make efficient use of space. Most of my organic garden beds have 10+ plants in close proximity.
Companion planting can get very technical, but it doesn't need to be difficult. A few guidelines can help ensure success, and the bottom line is that planting many complimentary plants close together is an important way to increase biodiversity in your garden, which creates a healthy, more resilient ecosystem.
Phil Nauta is a SOUL Certified Organic Land Care Professional. He's the author of the book 'Building Soils Naturally,' published by Acres U.S.A. He has taught for Gaia College and been a director for The Society For Organic Urban Land Care. He was an organic landscaper and ran an organic fertilizer business before starting www.SmilingGardener.com to teach practical organic gardening tips to home gardeners.