Two years ago, I planted potatoes for the first time in a bin made with straw bales; otherwise they would take up so much space in the garden, particularly if you are planting enough for winter meals. I constructed the bin over compacted soil on the outskirts of the garden where ropelike tree roots, heaved by granite just beneath the surface, covered the ground.
I planted the seed potatoes an inch deep in a layer of compost at the bottom of the bin, and every time the plants grew a foot, I added 6 inches of compost and straw. I added bales as needed to increase the depth of the bin and kept the top of the bin covered with a lightweight fabric to thwart the Colorado potato beetle.
It all seemed like such a good idea at the time. I kept envisioning a wheelbarrow filled with softball-size potatoes.
You may recall that it was an exceptionally cool and wet summer. Late blight ran rampant in nearly all Maine gardens, wiping out tomato crops and threatening potatoes, as well. While my potatoes escaped the blight and the beetle, they were a magnet for slugs that spent sunny days within the straw walls of the bin and rainy days and nights eating the leaves and stems of the potato plants. I estimated their numbers at a zillion. I surrendered in late July with a handful of egg-size potatoes, smaller than the original seed potatoes, to show for my effort.
In early May of last spring, defeated but not destroyed, I planted my ‘Prairie Blush’ seed potatoes in the conventional fashion, in hilled rows. In one of our sunny raised beds, I dug two shallow trenches, about a foot apart, in soil amended with compost. I then laid the seed potatoes in the trenches, about 12 inches apart, and covered them with about an inch of soil. Three weeks later, when the shoots were about 12 inches tall, I used a shovel to scoop soil from between the rows and mound it against the stems, burying them halfway. As the plants grew, I repeated this process, using either soil or compost.
From early June, when the shoots first emerged from the bottom of the trenches, until mid-July, I kept the potato plants covered with a fabric insect barrier. The fabric covered the entire bed, wide enough to be weighted down on all sides with large stones. There was no way that a Colorado potato beetle was going to fly or crawl onto the leaves of my potatoes.
In late August, we dug the first of a respectable crop of potatoes; the last in mid-September. They were gone by early October. We discovered that digging potatoes and eating them the same day are among the most gratifying garden experiences, worthy of the garden space that they demand.
Meanwhile, I read in the April-May issue of Organic Gardening an article titled “Raising Potatoes” that described the results of research on several ways to plant potatoes. Tests were conducted at the Organic Gardening test plots near Emmaus, Pa. Researcher Doug Hall compared several methods, including hilled rows, straw mulch, raised beds, grow bags, and wire cylinders. In the straw mulch method, seed potatoes were placed on the soil surface and covered with 3 to 4 inches of seed-free straw. More straw was mounded around the stems as they grew, eventually to a depth of more than a foot.
The conventional hilled rows method worked well, as might be expected from a proven method that potato farmers have used for generations. However, Hall points out that this method will not work in places where the soil is badly compacted or low in organic matter.
Of the alternatives, raised beds yielded the largest harvest. In this method, the soil is loosened in the bottom of a half-filled raised bed and the seed potatoes spaced about 12 inches apart in all directions, then covered with 3 inches of soil. As the potatoes grow, more soil is added until the bed is full. If the bed is constructed with removable sides, harvesting is very simple.
As for the straw mulch method, yield was slightly less than in the hilled rows. Hall mentions problems with field mice, but never discusses slugs. Of course, Pennsylvania is a long way from Maine.
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