Q. What's your take on growing potatoes in garbage cans? I was told it was easier to harvest because you don't have to dig them out of the ground, and it contains them in a smaller area. True?
---Rachel in Effingham, Illinois
Last year, I tried planting potatoes in 32-gallon trash cans. I drilled one-inch diameter holes in the sides and lined the bottoms with galvanized mesh. I put six inches of potting mix in the bottom of each can, put the seed potatoes in, covered them with mix, and as the plants grew, regularly added more mix, leaving just the topmost leaves exposed, until the buckets were full and the plants were growing out the top. One set of purple potatoes grew well, but the Yukon Golds wilted and the stems just fell out of the soil. What did I do wrong?
---Dave in Newark, Delaware
A. I'm surprised that any of your trash can spuds survived, Dave. Your technique of constantly adding soil over top of potatoes buried—what, three or four feet down?—sounds more like the way you're supposed to grow leeks or blanch asparagus. I fear that your spuds used up all their inherent energy just trying not to be smothered.
Now the basic idea of growing potatoes in some kind of above ground container is a very good one, as it eliminates the problems of trying to grow in dense, heavy garden soil and damaging the tubers at digging-up time. But you want a container with a wide top, so it can accommodate multiple sets of the above ground green plants that fuel the growth of the underground tubers. A more normally shaped container—like the 17-inch planters I recommend for growing big tomato plants—would be better, as their width nicely balances their depth. (If your cans are plastic, cutting them in half across the middle would give you two reasonable size planters.)
Fill the bottom two thirds of the container with the lightest, loosest combination of soil-free mix and compost you can achieve, place one to three certified disease-free seed potatoes on top of the soil (somewhere around one spud for each five to ten gallons of compost and mix) and then fill the pot up the rest of the way with more compost and mix. The green growth will be able to easily break the surface without expending a lot of energy; and with any luck, the containers will be filled with fresh, sweet juicy potatoes at the end of the season. Or you could harvest them as young, "new" potatoes in August, and then use the container to grow cool-season crops like salad greens.
But there's an old trick that allows you to grow lots more potatoes above ground in a less conventional type of container. And when I alluded to it on a show last season, we got a slew of emails from gardeners from Philly to Spokane asking for details on "Mike's method of growing potatoes vertically in a type of compost bin."
Hardly my idea, this trick was a favorite with the readers of ORGANIC GARDENING magazine during the time I was editor, and it really maximizes production while utilizing space well. You can either build your own 'potato bin' or use a classic "Lehigh style" composter—a four by four by four 'box' made of wooden slats that alternate with open spaces, so there's a slat, an open space the size of a slat, another slat and so on up to the top.
You fill the bottom of the bin with soil-free mix and compost until you reach the top of the first or second slat. Then you place one seed potato on each side of the bin—on top of the soil and centered next to an opening, a few inches back. Then you add soil and compost until you reach the next set of openings, place four more seed potatoes, add more soil and continue until you get to the top. The greenery that emerges from each seed potato will grow out of its adjacent opening and towards the light, fueling the growth of an enormous number of spuds in the center of the bin.
When you reach the top, add a last layer of potatoes, more compost and mix and then then mulch the surface well with shredded leaves as soon as the top plants appear. Keep the bin well watered; all that airflow and plant growth will use up water quickly. And make sure the top stays really well mulched over the course of the growing season; you never want the actual tubers to be exposed to light, just their above-ground green growth.
Typically, the bin will vanish in a sea of green by mid-season, with the lush plant coverage providing extra protection from light for the developing spuds. Enjoy the beautiful flowers when they appear on the plants, but cut them off as soon as they start to fade. Give the bin a nice organic feeding mid- season, let the plants die back naturally at the end of summer and then lift up the sides of the bin and collect your potatoes; you'll get the maximum amount possible—without any digging.
And if you'd like in ground potato growing info, just check out this previous Question of the Week.