How to Grow Sweet Potatoes in Tires
Sweet Potatoes in the Round
My favorite way of planting sweet potatoes is to plant them in tires around the edges of the garden. I do not believe that an easier way to grow sweet potatoes exists. Planted in tires two high, sweet potatoes grow like crazy. The heat that the tires produce, along with plenty of water, gives this plant the tropical conditions in which it thrives. By growing sweet potatoes in tires, they can be grown even further north than they could otherwise.
Although not related to the white potato, sweet potatoes are a tuber and are grown and eaten as though they were warm weather potatoes. Each tuber contains large amounts of vitamins A and C, as well as protein, calcium, magnesium, iron, and carotene. A tradition at Thanksgiving, they can be eaten raw, boiled, fried, or baked as well as in soups, casserole, desserts, breads, and in stir-fries.
At a Glance: Planting Sweet Potatoes
Sweet potatoes start from slips, not seeds. Start your own slips by sprouting sweet potatoes in a sunny window. Plant slips outdoors after all danger of frost has passed.
- Planting Depth: 6 inches deep
- Planting Distance Apart: 1 foot apart
- Time Until Harvest: 90–170 days
Just be sure to harvest your sweet potatoes before the first frost of autumn.
Concerns About Toxins
Some people worry about using tires to grow sweet potatoes, because they are afraid that the gas coming off the tires can be harmful. From my own research, I believe the gas and chemicals leaching from the heated rubber is a minimal problem at worst.
From my research, I believe that planting in tires over the short term is OK. Tires tend to get hotter than most plants like, however, that is not a problem with sweet potatoes. As long as sweet potatoes are kept well watered, and the soil in the tires is changed out every year, you should have no problems.
Over the long term, however, the tire's rubber will slowly release zinc, carcinogenic PAHs (polycyclic aromatic hydrocarbons), and other toxic compounds into the soil. The process required to break down tires takes many years, thereby making the hazards from a single season of sweet potato growing minimal.
How to Produce Slips
Sweet potatoes are not grown from seed, nor are they grown from the potato like regular potatoes. Instead, sweet potatoes are grown from slips.
To grow slips, save a few of the tuberous roots from your last crop, or buy untreated sweet potatoes from your local farmer's market. Six weeks or longer before planting outdoors, place them in a box of moist sand, chopped leaves, or sawdust and keep at 75–80°F.
When shoots are 6–9 inches long, cut them off the root. Put the root end into rooting compound and plant it into soil. Continue to root slips until planting time.
Planting Sweet Potatoes in Tires
Sweet potatoes will grow in poor soil, but they will become deformed if planted in heavy clay or long and stringy if planted in sandy soil.
I plant my sweet potatoes in aged sawdust mixed with small amounts of clay soil. I place tires two high in a sunny location around the garden's edge. To create the perfect environment, I fill tires with sawdust and clay mix in the tires and mix in plenty of compost. I do not add any extra fertilizers.
I plant two or three slips up to the top leaves into each tire and press gently, but firmly, into the soil. I then generously water the contents of the tires.
How to Care for Sweet Potatoes During the Growing Season
Allow your sweet potatoes to grow in the sunny location from the time you plant until the day frost kills the leaves. Water generously throughout the season. Be sure that plants get at least 1 inch of water each week throughout the season.
In the south, sweet potato weevils are a problem and can puncture stems and tubers to lay their eggs. They attack the leaves and stems and can also spread foot rot, which creates enlarged brown or black areas on the stems.
Fungal diseases include "black rot." Black rot produces circular, dark depressions on the tuber. Throw away infected potatoes. Small round dark spots on the tubers, however, are not black rot, but are scurf. Scurf does not affect eating quality.
"Stem rot" is another enemy that can be controlled by using certified disease-free slips and by rotating the crop. White hellebore planted nearby controls a number of leaf eating insects. If rabbits are eating the plant leaves, spray with either fish emulsion or a liquid kelp solution.
Harvest and Storage
Harvesting sweet potatoes grown in tires is so easy. Simply kick over the top tire and pick up the sweet potatoes. Dry sweet potatoes for several hours in the sun, then move them to a well-ventilated area and keep at 85–90°F for 10–15 days.
After cured, store at about 55°F at 75–80% humidity. They will store for several months.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2013 Cygnet Brown