By Jim Sincock
As we get ready for our second season with our micro-farm and CSA, we are looking into why a couple crops were less successful than they should have been. One crop in particular are the potatoes. While we bought excellent seed potatoes from a Colorado grower, I think our planting method may not be all that it is cracked up to be.
The Potato Tower! Yes, it sounds like some "Ronco" product (or a Saturday Night Live skit), but the concept sounded appealing. More appealing was the supposed fact that you could get up to 100 lbs of potatoes from one 3' x 3' tower. Great, we had two towers, so we should get 200 lbs of potatoes! In theory. The theory being that you plant you seed potatoes in about 18" of soil, then when the stalks grow 6", you layer on more soil, and the plant will produce tubers where the stalk is in contact with soil. On top of such a harvest potential, they take up little space which is great for home gardeners, or micro-farmers. Perhaps the best part is you don't have to dig the potatoes up, just pull down the tower! Great theory, but it didn't prove successful for us.
Throughout the season we kept piling on the soil as the stalks grew. They were growing like crazy, and looked very healthy and vigorous. Everyone was curious about these towers, and couldn't wait to see the "huge" harvest. As the season neared an end, and the CSA's final harvest was coming up, it was time to harvest the potatoes. I eagerly started pulling apart the towers, and some of the first potatoes I found were of a nice size. Beautiful red potatoes! Pulling down more soil, I quickly saw that their wasn't going to be 100 lbs. of potatoes in the tower. Maybe if all the Robin's egg sized potatoes were a full size, maybe then the yield would have been larger.
After our two towers were down, and I had sifted through all the soil, we had 25 lbs. of potatoes. Two 3' x 3' towers with 5 lbs of seed potato in each... 25 lbs. Well, it was enough to give each CSA member 1 lb each. And I have to say they were the best red potatoes I've ever had!
So what went wrong? Not enough water? No, while there were times the towers got neglected with watering, the plants were very happy, and the soil seemed damp enough when I took the towers down. Planted too late in the season? This is a possibility, but I don't think we were too far off from the optimal planting date. Not enough nutrients? The soil in our towers was a mix of suitable dirt, llama manure, and some straw mixed in. I don't think the soil quality was the issue. Harvested too soon? Yes, in fact we did harvest before the foliage died back since we wanted our CSA members to get potatoes in their final box. My guess is we may have had 2-3 more weeks before the foliage died back. I can't imagine that amount of time would have made much difference on the very small potatoes. Potato towers - fiction? Maybe! As I was researching potato towers this morning, an article (and ensuing comments) on One Straw made me think that potato towers might not be the way to go. Rob (at One Straw) had a very similar experience with his potato towers. As did many of his readers who commented on his article.
This year I guess we'll either try a sheet mulch mound, or 5 gallon buckets, both sound like they are more successful methods. You can read a little about them in this article on One Straw.