I’ve been frequently asked to write about trashcan potatoes. I haven’t yet, simply because I don’t have a trashcan to use for that purpose. Instead I used what I had and am experimenting with milkcrate potatoes. I’ll let you know how it works.
The potatoes that work in trashcans are any of the standard potatoes in the Solanaceae family, related to tomatoes and eggplants; sweet potatoes and yams are in the morning glory family and grow very differently. A good article with photos that shows growing potatoes in a barrel is at greenupgrader.com. There are many videos on the web about growing trashcan potatoes; a good one is at Farmers Almanac . Two things that she does in this video that I do differently is that after cutting the ‘eyes’ of the seed potatoes, I allow them to harden off for a day or so before planting, and also potatoes can grow with less than 8 hours of light a day which makes it a good over-wintering crop, especially here in Southern California. Potatoes like shorter daylight and cool night temperatures, so plant now! If you plant later, protect the trashcan from the afternoon sun. Hardening off means to allow the cut potato to sit in the shade for a day or so to allow the cut end to form a ‘scab’, or harden up before planting. It helps keep the potato eye from molding and provides protection from insect or bacterial attacks, and keeps drier soil from leaching water out of the potato. This is the same process you’d do when taking cuttings from cactus, geraniums and other easily-rooted, sappy plants. When watering trashcan potatoes, don’t overwater because you’ll rot them. Like their cousin the tomato they’ll do better slightly drier than wetter.
‘Seed’ potatoes aren’t potato seeds. They are small tubers that are ready to plant. Always buy organic seeds. Period. You can buy seed potatoes online or in nurserys available in Southern California just after Christmas, and sometimes in the late Fall. They usually purchase the seed from other states which have snow and don’t ship during the winter. Buying online or from organic catalogs allows you to shop among a wide variety of potatoes differing in size, color and purpose. However since we can plant potatoes in the Fall and don’t want to wait for shipping times, we can buy a bag of organic potatoes locally and sprout them ourselves. Non-organic potatoes have been treated so that they don’t sprout in the store, and are genetically modified (GMO) to last on the shelf. Sprouting potatoes is called ‘chitting’ and is very easy. Mine usually sprout in a bowl on my kitchen counter. Keep them in a light, cool area out of direct sunlight and they’ll grow. When the potatoes have chitted and ‘greened’ (have sprouts), you can either plant them whole or slice them so that each piece has at least one eye. Allow them to harden off and plant them. Give the extras to your neighbor!
The reason for growing trashcan potatoes is that you can grow vertically, save garden space, and in particular save your back from trenching, hilling and then digging. The harvest is more productive, too, because you won’t be accidentally cutting through or spearing potatoes in the ground. Potatoes can grow this way because the tubers are actually specialized underground stems called stolons. Potatoes will produce tubers underground, but anywhere along their stems they also can grow a potato under the right conditions. Once you plant a potato ‘eye’, the eyes being the growth buds, it will send out stolons. The plant will produce potatoes below ground, and if you hill up around the stems they will also begin to swell and produce tubers.
When you plant in a trash can (with drainage holes!), as the greens shoot up you keep layering compost or straw or woodshavings or potting soil or whatever around the stems keeping a little green showing until you can’t fill the trashcan anymore.
When the plant is done growing the plant will bloom and sometimes even produce seeds. When the stems die back, you knock over your trashcan and harvest. Save some of the smaller ‘taters for seed for planting in the Fall.
You can also root around in there earlier and pick new potatoes, or you can delay your harvest, keep water out of the trashcan and keep it in a cool spot, and harvest when you want them. The beauty of trashcan gardening is that you don’t need a trashcan. Very zen! You can drill holes in a plastic carrier, use burlap sacks, stack old tires, nursery containers, large plant pots or whatever you have. If you have a bottomless or rusted out trashcan, use it! Place it over good garden soil and allow the potatoes to grow down, too. You’ll have a little digging to harvest after you knock over your trashcan full of potatoes, but not much. To make holes in a plastic or aluminum trash can, borrow a digging bar (a long metal pry bar), place your trashcan right-side up on a dirt area, hold the bar high vertically over your trash can pointy side down and let it go. It should make a hole. Or turn the can over and use a hammer and something sharp like an awl or screwdriver (be careful you don’t shatter the top of the screwdriver! You don’t have to pound too hard. Be wise and wear safety glasses just in case). Do this multiple times to make as many holes as you can without making the bottom unstable.
Also be sure to keep the trashcan or crate potatoes in a cool place, especially if you are planting in the early spring here in Southern California. Warmth will keep the potato stems from swelling into tubers. Insulate the potatoes well and keep them cool while still allowing them enough sunlight. Fall and winter are the best times for planting potatoes here, as long as they have adequate drainage.
There is concern about leaching chemicals from plastic, or tires, or aluminum. Do the research and make yourself happy. I don’t think there is that much leaching to be worried about because the plants aren’t in there for a long time. You can always make a barrier between the soil and the sides of the containers with undyed paper or newspapers using soy ink. So save your garden space for other crops, and pop your ‘tatties in a can. Or crate. Or whatever.
Update: here is a very comprehensive article about planting potatoes. Rather than use commercial fertilizer, of course, we recommend rich compost, which will provide what your potatoes need. Also use dead garden debris such as old pea stalks (cut rather than pull them up to allow the nitrogen nodules on the roots to remain in the soil) in your planting bed or container.