How to Grow Onions in Tires

Set a tire with one of its flat sides down on a flat, even surface. Placing it on the ground is fine, but you may use a sturdy picnic table or work bench if it is more comfortable than working on the ground.

Insert a heavy-duty utility knife blade into the tire's sidewall, which is now facing up on your work surface. Cut around the circumference of the sidewall, working in small increments and rotating the tire between cuts to achieve the best leverage. Lift the cut-away sidewall and discard it, leaving the tread section of the tire to serve as the container's sides.

Place the modified tires, uncut-side-down, in an area that receives sun for the majority of the day. You do not need to turn over the ground, but do remove debris, mow and rake away any weeds.

Fold a black plastic trash bag into a square just large enough to cover most of the open area in the bottom of your tire planter, but small enough that about 2 inches of bare ground remain exposed on all four sides when you set the folded bag in the tire. These open spaces serve as the drainage holes for your onion planter. Set a stone on each corner of the bag to hold it in place as you fill the tire container.

Fill the bottom half of each tire with topsoil. Fill the remaining half with alternating 1-inch layers of compost, builders sand and top soil. Stir occasionally with a trowel as you add layers to ensure the components are mixed well.

Water the newly filled tires once or twice over the next week and let the soil mixture settle. If you are in a particularly cold climate, or one with a short growing season, cover the tires with sheets of clear plastic to warm the soil.

Plant onion seeds, sets or transplants in the soil, starting at the center and working outward toward the tire's edges. Space green onion seeds 1/2 to 1 inch apart; you may thin them later and use the shoots in the kitchen. Allow 2 to 4 inches between each onion set or transplant, depending on the variety you plant.

Water the tire container frequently during the first month after planting the onions to keep the soil moist as shoots emerge and become established. Thereafter, apply water whenever the top 1/2-inch of soil dries out.

Harvest green onions as needed until hot weather sets in and the plants begin to to go to seed. Pull full-sized onions after their tops have fallen over and begin to dry out.

Top up one or two of the tire containers with compost and soil to plant a batch of green onions for autumn harvest. Mix aged manure and compost into tire planters that are left sitting to raise onions again next year. Replace all the contents in the tires after two to three seasons.