How to Grow Potatoes in a Feed Sack by Jane Sommers, OSU Marion County Master Gardener
Why would you want to grow potatoes in a feed sack, you ask? Maybe you don’t have a lot of space. Maybe you like gardening in containers. Maybe you have a bunch of feed sacks lying around doing nothing worthwhile. Maybe because it’s fun.
What kind of feed sack should you use? I recommend a sack that about 50 lbs. of feed comes in. That is large enough to give a roomy home to a potato and it is easy to come by. Use a sack made of woven or molded polypropylene (basic plastic feed sack material). Many livestock feed sacks have colorful images on them and can be quite pretty. Avoid using burlap sacks, as they will probably rot before it’s time to harvest your potatoes. If you don’t have your own feed sacks you might know of somebody with livestock and some feed sacks they want to get rid of.
Prepare your sack by poking a bunch of drain holes in the bottom. Set it in a sunny spot on something that will allow it to drain – a gravel area, an old BBQ grate, whatever is available. (Setting it on soil might block the drain holes.) Then roll down about 2/3 of the top of the sack so it is about 14” tall.
Fill your sack with 12 inches of compost or compost blended with leaf mulch, sawdust, or straw. Potting soil is OK too, but potatoes really like a lot of fertility and don’t mind organic matter, if that’s what you’ve got (I had great success one year using the sawdust litter that l had raised turkeys on – about 30% poop and not even composted). Plant one seed potato per sack. Potatoes like a bit of water, but they don’t like to be soggy. Water when the top inch or so of soil is dry.
When your potato is about a foot tall, roll the top of the bag up until the plant’s head is just sticking above the edge and fill it up with more compost. Do this one more time if your potato gets tall enough. The idea here is that The plant will be able to produce tubers along the entire buried stem instead of just at the base. It’s the same principle as hilling potatoes grown in the ground.
You can harvest your potatoes when they are done flowering, for new potatoes, or after the plant starts to die back in the fall for mature or storage potatoes. Harvesting is easy: pick up the sack and dump it into a wheelbarrow, then spread the soil and pick out your potatoes. Then dump the rest into your compost pile.