Potatoes in pots - is it just hype? by Helen Gazeley
By: Steve Ott
So, when my husband came home with two packs of potato planters I had to bite my tongue. No point in discouraging food production, even on a bijou scale.
The popularity of growing potatoes in containers isn’t all down to the activity of gardeners who lack space. There’s also the suggestion that, if you earth up the stem as it grows, it will send off more potato-producting shoots, or stolons, and you’ll get a much bigger harvest, distributed throughout the container.
Not according to the RHS, which in its April edition of The Garden wrote, “Contrary to adverts, potato plants only produce potatoes around 12 inches below the soil level.” Earthing up would not, they added, increase yields.
But are they right? In 2005 an American grower, Greg Lutovsky, stated in The Seattle Times that, by growing potatoes in a box, you could “steal” them from the bottom of the box (removing the bottom slats, then replacing them) throughout the season. “Unless you steal all of them during the growing season, in the fall you should end up with a box of spuds—as much as 100 lbs.”
It’s a seductive idea. The secret, purportedly, is to bury the plants as they grow, with dedication. Leave the potato tops to grow more than four inches before burying three and the stems will no longer feel inclined to send out stolons.
It’s certainly sparked a lot of experimentation. Showing some promise was an attempt by OneStrawRob. One tower contained potatoes 18 inches above seed potato depth, “far higher in the soil than one would ever expect from conventionally grown potatoes”. Others towers were “complete failures”.
This is a common experience. Johanna Silver at Sunset harvested 6 ½ lbs from a tower about three feet high (and they were all at the bottom). Jim Sincock at LandShare Colorado managed 25lbs from two towers, but again the potatoes were all at the bottom.
The blogger at Sinfonian’s Garden Adventure harvested only 10lbs of 'Yukon Gold' and 25lbs of Organic Butte and, you guessed it, the harvest remained resolutely in the bottom six inches of the box, where the seed potatoes were originally planted.
Greg Lutovsky is CEO of Irish Eyes Garden Seeds where you can find instructions on How to Grow 100lbs of Potatoes in 4 Square Feet. The website’s FAQ section confusingly describes growing potatoes in containers as “only mildly successful” but elsewhere Greg says that some potatoes are more successful than others. He advised Sinfonian that early varieties don’t do well in towers. The varieties he recommends—'Yellow Finn', 'Red Pontiac' and 'Indian Pit'—aren’t available in the UK
Phillip Cairns, a Newfoundland bee-keeper, and his wife, have put three years of effort into potato towers and blog about it at Mudsongs. Success has been elusive. This year they’re giving it a final try, and are letting the plants grow well into the autumn: “We did exactly what we did last year and were careful to cover the plant stems as they grew. We used a local late-season variety seed potato, planted them in 100% composted soil, gave them some fertilizer and we kept them well watered. We're hoping for the best, and so far the plants are growing well.”
His advice is to plant potatoes that you know grow well in your area; choose a main-crop potato that will set tubers throughout the summer; earth up every day to an inch below the tops (until they reach the top of the box) and avoid limey soil.
Hope is fading, though. Cairns adds, “We'll update the page on our website if the mini potato tower is successful (though we have our doubts).”
Sinfonian is also sceptical. “Friends of mine in other parts of the country have had mixed results with this method. In fact, I have yet to see anyone get 100lbs from one of these.”
Perhaps no one has managed to do it right. Continual earthing-up isn’t that easy. Our potato plants certainly got away from us; one moment green leaves are showing just above the surface, the next they’re peeping over the top of the container. You feel if only you’d been more assiduous, chosen exactly the right variety of potato, the promise might have been fulfilled.
Not according to potato expert Alan Romans. He and Colin Randal of Thompson and Morgan conducted their own experiments at Capel Manor a few years ago. “Just a disaster,” is the way he describes it, and is of the opinion that the weight of compost squeezed air out from where it was needed. “The potato is a modified stem tuber; if anything it needs more air than normal tuber.” The results were half-grown, half-cankered potatoes. The way to get a large potato harvest is “deep cultivation, loads of space and loads of fertilizer,” adds Romans.
And it’s worth bearing in mind that commercial growers do everything possible to increase their yield, yet manage around 25 lbs of crop per lb sown—considerably less than the tantalising prospect of 100lbs from a four-foot box.
If you are interested in having a go, then it’s worth reading OneStrawRob for his recommendations. One of his conclusions? “It’s not easy, it is not guaranteed, and it needs a lot more research and realism before anyone goes filling the internet with wild claims.”
Meanwhile, what luck for my husband? Well, as expected, all the potatoes ('Rocket' and 'Kestrel') were at the bottom of the containers. Something that might prove worthwhile would be plant potatoes at the bottom, and then another layer half way up the sack, making use of its height. Per container we harvested around 4 ½ lbs from around 2 lbs of potatoes. Not brilliant, but in common with the bloggers above, we found the harvest to be in perfect condition and very good looking.
There was also, for me, a major benefit. With a bad back, I appreciated being able to tip the bag and sift the contents without wielding a spade. So much so that I might have to admit that my husband came home with a good idea, after all.
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