A Beginner’s Guide to Container Potatoes
Field & Garden
By Lori Fontanes
I know what you’re thinking: what’s so special about potatoes? With all those ubiquitous orders of fries and mashed platters, why do I need to bother growing any of my own?
Well, there’s one good reason—taste. You haven’t tasted a truly delicious tater until you’ve eaten one you just dug up and cooked for yourself. Seriously, there’s simply no comparison between store-bought and backyard spuds. And better yet, potatoes are one of the easiest vegetables to cultivate, especially when you grow them in containers.
START OUT RIGHT
To ensure the most delicious results, I always start with certified organic seed potatoes from a trusted source. On the East Coast, my personal favorite is Wood Prairie Farm in Bridgewater, Maine. This family business offers wonderful personal service, enthusiastic support of organic growing and high quality seeds of all kinds. Keep in mind that good seed potatoes are in demand, so get your order in early. I’ve been disappointed in the past by waiting until the last minute only to find my preferred variety already out of stock. On the other hand, you don’t want your starter spuds to arrive before you’re ready to deal with them. It’s best not to have them sitting around for more than a couple of weeks.
After you choose a good source for seed, then it’s time to pick the type of potatoes you’d like to grow. Most important consideration: what kind do you like to eat? Maybe it seems obvious, but sometimes we backyard farmers get carried away with things that are easy to grow rather than things our families enjoy. For example, there was the time I grew 30 pounds of radishes and no one but me would eat ‘em. No worries, though. I sweet-pickled the leftovers. They all went after that!
So, with the taste-bud caveat in mind, you can now wade through the staggering array of potato choices that many growers have on offer. Take your pick from a range of colors (ivory to deepest purple) or sizes (slender fingerlings to massive russets), or by texture (creamy to dry) and other features such as storage life, growing time and disease resistance.
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WAIT, WAIT, THERE’S MORE
Choosing the right container is key to growing—not just successfully, but safely, too. I know a lot of gardeners have gotten sizeable crops by raising veggies in various vessels, from the bizarre to the merely available. As someone who’s been involved in a long-term study of soil contamination, however, I’m here to tell you that what’s in the container can also get into the soil and from there, into your plants.
According to recommendations from the New York State Department of Health and Cornell University, you should avoid treated wood, railroad ties, telephone poles, pressure-treated wood and even some painted woods. Tires, by the way, are also not a great idea. (I know! I know! Everyone does it but, really, no.) These sorts of containers may leach unfriendly chemicals, which make them very unappetizing for supporting your spuds.
In our garden, we use Smart Pots, a made-in-the-USA fabric container that comes in two sizes, 15 and 25 gallons, holding about three to four, and four to five, potato plants, respectively. We generally use the smaller bag because eventually you have to replace the soil and I find those large bags a bit too unwieldy. The great advantage of a bag, by the way, is that you start with the sides rolled down when the seeds are first planted and as the plants grow, you gradually roll the edges back up. Simple, effective, durable and at less than $20, not that expensive.
Other container ideas include building a stacking frame of non-toxic woods, also durable and easy to use, but a lot more work if you have to build your own. If you’re good at DIY, there are plenty of plans on the web for constructing stackable frames.
Some folks also like to use trash cans, but again, I’m not big on chemicals getting into my food and the idea of those plants baking in the hot summer sun inside a black plastic container is not that appealing.
YOU’VE GOT SEED
After you’ve made your selection and the post office finally delivers your little ventilated bag of future French fries, open the box right away. The instructions from the grower will tell you how to appropriately store the seed potatoes, generally in a cool, dry location, and not the refrigerator. Wood Prairie Farm recommends removing the potatoes from their sacks if you won’t be able to plant in less than two weeks.
Depending on when and in what state of readiness they arrive, your seeds may already be sprouted and suitable for immediate planting. If not, Wood Prairie says you can place these starter potatoes directly in the light to accelerate the process, although others suggest this is not necessary. (I leave them under a towel on a shelf in the pantry.) Either way, try not to wait too long as the spuds may begin to dry out and shrivel. Check on them about every other day to ensure you don’t miss the right moment. Once they’ve developed a sufficient number of sprouts, at least two “eyes” on each potato if small or two per piece if you are dividing larger spuds, you’re ready to get them into containers.
Assess the weather for the upcoming weeks before planting (or even ordering, if you want to be really fastidious). Potatoes can be started in spring for early summer harvest, but if your weather will be persistently cold and rainy, there’s no advantage in planting too soon, as the seeds could rot. Make sure the soil is at least 50 degrees and if the weather gets hot and dry, be extra vigilant about providing sufficient and consistent water.
On the day I decide to plant, I take a clean cutting board, slice the seed potatoes into the appropriate size (about 1.5-ounce pieces) and head directly into the garden. I line the bottom of the fabric bag containers with 4 to 6 inches of good quality organic potting soil and place three to four potato seeds in each bag, roughly dividing the growing space into equal portions, and then covering the pieces with a bit more soil. For a larger bag, I can fit about five seeds quite comfortably. Even if you have extra pieces left, don’t be tempted to use them. Overcrowding will not end well!
Potato plants are not heavy feeders, but starting with good soil and some compost should maximize yield. For extra nutrition, I’ve used bagged worm castings mixed with the soil for planting and had excellent results. In addition, Wood Prairie recommends foliar amendments such as Liquid Fish (Neptune’s Harvest) or soluble seaweed powder (Acadian Seaplants extract from Fertrell Co.) sprayed on plant leaves four to six times per season. I’ve given my plants organic fertilizer some years, but to be honest, I get pretty busy with all my farm duties and often forget. I’ve never had a bad crop, so I’m guessing the quality of the initial soil and the seeds are the best predictors of successful outcomes. Water well and keep the plants watered evenly—not soggy and not dried out—for optimal results.
KINGS OF THE HILL
Now comes the fun part (to me, at least): watching for those first green tendrils as they emerge from the soil. Depending on the weather, this generally takes about 10 days, and soon after those first curly leaves break through the surface, you’ll need to keep a good eye on the plants as they grow quickly. (Later there is very little work, however.) You are looking to see when all of the plants reach about four to six inches in height. When that happens, you will do this thing called “hilling,” which is farmer jargon for taking more good quality potting soil and adding it to the bag. The idea is to keep the developing taters from being exposed to sun. Try not to cover the leaves as you add soil to the entire bag, not just around the base of each plant.
Do this every time the plant grows another four inches or so, unrolling the sides of the bag as you go. When you reach the top of the bag, your plants should be quite big and bushy and still growing, but they will also be surprisingly delicate. Take extra care as you handle them, as parts will break off easily.
I learned early on that using a small trellis or other support is critical, especially in heavy downpours and windy conditions. Also, we have ducks who like to jump into the bags to lay their eggs (who knew?). To protect against all of these challenges, I create an ersatz cage of trellises to deter varmints and provide a climbing surface for the sprawling potato vines.
Once your plants reach full size, you will be treated to the charming sight of the tiny potato flowers. Any time after these blossoms fade, you’re welcome to dig into the soil and harvest a few. I rarely jump the gun this way, but have heard that the small, early spuds can be quite delicious. If you take these first fruits, though, make sure you cook them right away, as they will not be suitable for storage.
Generally speaking, I wait until not only the flowers have died off, but when the vines themselves begin to wither. At that point, I can be confident that the potatoes have reached full size and, boy, can they be quite hefty, even when grown in a fabric bag. Carol Deppe, author of The Resilient Gardener, recommends waiting at least two weeks after the vines have fully died back to maximize nutritional content and to make sure the potatoes are cured and ready to store. Depending on your area’s climate, you can also pick potatoes when you need them, leaving them stored in the bag’s soil until conditions turn cold and wet again when you must remove them, or risk having them rot.
Indoors, experts recommend that potatoes be stored in cool, moist spaces (38°F to 40°F), but unfortunately, in the summer, I don’t have any place in my home that meets those requirements. Refrigerating potatoes alters their starch content and is not recommended. If you also do not have optimal storage space in your homes, harvesting on the go may be the best strategy for you. You could also consider succession growing your crop: planting one bag every two weeks. The only downside is that you will probably have extra seed potatoes left over. Or just decide to grow a ton of spuds!
SAME BAG, NEXT YEAR
In the fall, after I’ve dug every last potato from the bags, I pull out the plant debris and cover the soil with straw to shield it from winter extremes. Then, since i have a full bag at the beginning of the next planting season and I need an empty bag before I can start the next potato crop, I usually do one of two things.
First, I may choose to plant a quick spring crop in the existing soil (i.e. radishes or lettuce). If you do this, however, be careful with your timing. I’ve also tried growing peas in last season’s potato bags but ran into trouble—the peas weren’t podded by the time I had the seed potatoes ready to go, and I ended up having to reorder. Oh well!
Alternatively, I’ll skip the first planting and just take the rich soil to amend the flowerbeds before refilling the bags with new soil and starter potatoes. Also, if your potatoes are harvested by August, you may be able to do an autumn crop, too. I like to do peas in fall to add nutrients and then another kind of crop the following spring.
ONE POTATO, TOO MANY POTATOES
How many potatoes can you expect to get from one medium-size bag? It depends on factors including soil and compost quality, consistent watering and productivity of the variety. Last year we grew enormous, low-maintenance Yukon Golds with large individual taters and heavy overall yields. In general, though, we get about five pounds per bag, planting four bags per season. I’ve read brags on the blogosphere with even higher numbers, but believe me, 20 pounds of spuds is plenty for my family. Although, come to think of it, can there really be such a thing as too many French fries?
David Deardorff & Kathryn Wadsworth, What’s Wrong With My Vegetable Garden?; Timber Press; Portland, OR. 2011.
Carole Deppe, The Resilient Gardener: Food Production and Self-Reliance in Uncertain Times; Chelsea Green Publishing; White River Junction, VT. 2010.