October 18, 2011 by Kevin
Sweet Potato Harvest from Polyculture
We experimented with a few different polyculture combinations this season. Some seemed to produce and work well, others not so much (more on polycultures and our experience with them in a later post). One polyculture that did seem to be promising was the sweet potato/bush bean/beneficial weeds polyculture. This year’s sweet potato harvest resulted in yields that seemed to be comparable to a single bed or rows of sweet potatoes.
[Sweet potato and bush bean polyculture with some volunteer flowering plants popping up here and there]
What is a Polyculture?
A polyculture can be thought of as the opposite of a monoculture crop. A monoculture is a planting of one single species like in a large field of corn or garden beds of single species. Polyculture combines different plant species together in the same space, similar to what one would find in a natural ecosystem. The idea is that a more bio-diverse system will decrease the chance of widespread loss to disease, provides more habitat for beneficial insects, and provide mutual benefits between each plant species. Inter-cropping and companion planting are a less complex form of polyculture, but the ideal polyculture will have many different layers of complexity with a high species diversity. I recommend Gaia’s Garden by Toby Hemenway for a detail understanding of polyculture and its benefits.
Sweet Potato Bush Bean Polyculture
We planted this polyculture in a 10′x3′ ground raised bed. The sweet potato transplants and bush bean seeds were planted in a somewhat hexagonal spacing technique similar to what is describe in the Biointensive gardening method. Our garden beds are no-till. A top layer of compost was added to the bed a week before planting. Both sweet potato and bush bean seeds were planted at the same on May 8th. We started harvesting beans in early summer through fall, though as the sweet potato vines began to take over towards the end of the summer chocking out some of the bush beans.
In late spring a layer of grassing clipping were added to the bed for mulch which lasted most of the growing season. All of the flowering plants in the polyculture came up as volunteers.
“What if we could blend the best qualities of interplanting and companion planting? Interplanting combines crops that minimize competition for sun and nutrients. Companion planting blends varieties that enhance each other. Natural plant communities, tuned by billions of years of evolution, do both. Why not emulate these plant communities in our gardens?” – Toby Hemenway, Gaia’s Garden
While not as complex as some polycultures, the sweet potato/bush bean/wildflowers (in my opinion) go beyond companion planting and interplanting. The sweet potato vines provide a living mulch that suppresses weeds and protects the soil from erosion and the sun (conserves moisture). The bush beans are legumes and are able to provide nitrogen to the soil. The wildflowers found in this bed are cleome (spider flower), garden balsam, and rose moss. All of these come up as volunteers all throughout our gardens. All three are excellent at attracting beneficial insects that will act as pollinators and predators to help balance pest problems. Rose moss also can be an excellent ground cover, though the sweet potato vines already do an excellent job in this bed. Garden balsam is also edible and has medicinal value.
Sweet Potato Harvest
One should harvest sweet potatoes after the first frost has killed the plants or when day time temperatures have dropped into the 50s F. Dig the tubers with a pitch fork and if any get bruised, use those first because they will not store as well. Cure tubers by laying them out in the sun for a day followed by a warm (80 F) humid location out of direct sun for a couple of weeks. Finally store them in a dry, cool spot. They should store up to 5 -6 months.
If anyone has any experiences they would like to share concerning their sweet potato harvest, sweet potatoes in a polyculture, or anything related please leave a comment.
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