Polytunnel growers can use all sorts of techniques in order to maximise yield in the space available to them. One of the key techniques that can be used is that of companion planting. The three sisters planting scheme is one of the best-known examples of companion planting. Native Americans often planted three different vegetables together, and called them the ‘three sisters’. These three plants were sweetcorn, green beans and squash, or pumpkins. Like sisters, each of these plants has different characteristics, and those characteristics can aid the other two.
Sweetcorn grows tall and strong, creating a support up which the green beans can climb. Green beans fix nitrogen from the air with bacteria on root rhisomes, ‘feeding’ her sisters. Squash or pumpkins cover the ground around, creating shade and helping to conserve soil moisture. As Native Americans knew, planting these three crops together can make all three thrive
Why Choose Companion Planting?
Though, obviously, the climate in the UK is very different to that in most of the United States, a polytunnel can allow UK gardeners to emulate our American cousins. While it may be difficult to grow sweetcorn outside in more northerly parts of the UK, in a polytunnel, growing sweetcorn is easy. Especially when you plant it with its ‘sisters’.
Companion planting is sometimes an inexact science and the many interactions between different plants can sometimes be difficult to explain. The ‘three sisters’ companion planting scheme, however, is very much tried and tested. These sisters have been planted together for generations, and many gardeners have discovered the benefits of growing polycultures of this type. Our companion planting guide covers the basics of these techniques to help out beginners.
Three Sisters Planting Tips
When establishing a growing area for a three sisters companion planting scheme, it is important to remember that sweetcorn will do best when planted in blocks rather than thin rows. Aim to plant at least nine sweetcorn plants in a grid, so they can be wind pollinated more effectively by one another. Remember to allow good ventilation in the polytunnel during the summer months.
Sow two green beans at the base of each sweetcorn plant, close enough to allow them to climb up the sweetcorn as it grows. Next, sow some squash or a couple of pumpkins in the same bed as the other plants, making sure each has space to expand to cover the ground around the sweetcorn and green beans. Don’t forget how large these vining plants can become.
The three sisters will take up rather a lot of space in a polytunnel, but these crops could be a good use of this space, and when you plant all three in the same bed, you will enjoy three yields, effectively for the price of one. Have you tried the three sister companion planting before? Let us know how it went.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.