The post I wrote on growing potatoes in containers last September is currently attracting quite a bit of traffic, reminding me that I promised to round up the advice of bloggers who'd had a go at growing 100 lbs of potatoes in a 4 foot square container.
Just to recap, the idea is to earth up potatoes as they grow, with the idea that the plant will continue to produce stolons (and therefore potatoes) along the length of the stem, filling the container with potatoes at all levels. Results have been, almost without exception, disappointing, with potatoes at the bottom of the container, where the seed potato was placed, and a lot of empty soil above.
But... Let's revisit Phillip Cairns at Mudsongs. He had a go three years running, honing his methods but without great success. Last September he wrote to me: "If we don't get good results this year, we're done trying. We'll update the page on our website if the mini potato tower is successful (though we have our doubts)."
Well, go and have a look! Against his expectations, he harvested 33 lbs (15kg) of potatoes, double his previous year's yield. He says:
Many of the potatoes we harvested from our mini tower this year grew near the top of the tower just below the surface of the soil (and most of them were large potatoes), which seems to indicate that the potato tower hilling process actually works.
So, it seems that it just might be possible, despite expert opinion.
Now, quite obviously I should have written this a month ago, when the maincrop potatoes generally get planted, but if you have a few tubers lying around and fancy attempting a large harvest from a few potatoes, then here's some of the advice from those who have tried it.
Above all, you must earth up. As the stem emerges from the ground, it's no use leaving it for a few days, then earthing up to the top of the stalk again. It must be done as the stalk emerges. As Phillip Cairns says:
The key is to cover the stalks while they’re still soft. If the stalks have a chance to get hardened by the sun, they won’t transform into roots and the extra potatoes won’t develop. So if you plan to go away for a week while the plants are still growing, it’s game over.
And Sinfonian agrees:
I think I got lazy in hilling my potato plants... Sometimes I would let them get to be 8 or so inches tall and jungle-like before dumping more dirt in and covering the stems. I now know that causes the plant to become a stem rather than a root, stopping growth.
So, if you don't earth (or hill, in American) up, you don't stand a chance of getting a crop that fills your tower. Now, here's a round-up of other conclusions from Mudsongs, Landshareco, Sinfonian's Garden Adventure, and ne Straw Rob. Do visit their websites, if you haven't already, as you'll get a good idea of what they did and how they did it.
- Use potatoes that you know grow well in your climate.
- Choose a late-season (maincrop) potato, so that they have a long growing period.
- Avoid any lime in the soil, as potatoes arent' keen on it.
- Earth up.
- Ensure potatoes are well watered and that drainage is good. General impressions are that the potato towers retain water well, but you want to ensure that the soil at the bottom remains damp but not waterlogged (otherwise the potatoes may rot).
- Experiment with different cultivars. Some seem more prone than others to produce roots along the stem, so it's worth having a couple of cultivars, but best to plant one cultivar per container, as different growth rates can, says One Straw Rob, make earthing up difficult.
- Don't make your potato tower too tall: 20-24 inches seem to be all you need.
- Don't harvest too soon. Leave until the foliage dies back.
- And, finally, don't forget to earth up.
If you have a go, please come back and tell us how you did. My suspicion is that you can force a bumper harvest from a potato plant, but that it takes the right cultivar and assiduous attention.
Catch up with previous posts: