There are always crops which keep me humble, which raise questions of timing, fertilization, and care, which do not come out as I intended. One year it was beans, another year, winter squash. My 'Russian Banana' fingerling potatoes were the crop this year.
I planted them from one year’s saved seed on March 21st. They grew gloriously, flowered during an early warm spell in mid-April, and died down by early July, which felt a bit early until I counted back to the planting date. I pulled them from the ground because I needed the bed for some fall crops. After harvest, I was struck by the small size of most of the potatoes. I had raised a crop of tiny tubers. Why?
I did some research. After being frustrated with online sources, I came across the book Advances in Potato Pest Biology and Management, which I studied avidly.
Crop Rotation Considerations for Potato Planting
Sources recommend planting only new, certified clean seed potatoes every year to avoid soil diseases, which can wipe out entire crops. This can be true — I leave gardeners to determine this for themselves — but the original potato farmers, in the Andes, did not start each year with fresh seed. How did they keep their harvests strong year after year, for hundreds of years?
According to David Thurston in Andean Potato Culture: 5,000 Years of Experience with Sustainable Agriculture, they rotated their fields, leaving them fallow for 2 or 3 years and growing other crops for several years as well, before replanting potatoes. When the Europeans arrived, they saw “wasted” fields, not being used for crops, and used this as an argument to take the land.
There were potatoes in this bed last year — should I watch my rotations more carefully? Rotation of crops is difficult in a home garden which consists of ten raised beds. But, if I grew four types of potatoes and restrained myself to two beds each year, and maybe grew dried beans for a year occasionally, I could rotate through each bed once every 5 years. That could help.
Seed Saving and Waning Productivity
Experts discourage saving your own potatoes, because of disease and a waning productivity. I carefully studied the illustrations and descriptions of all of the diseases which impact potatoes — and there are many. None of them described what I was seeing, which was a remarkably clean but small potato, coming from very healthy vines. These potatoes were not diseased.
I have certainly seen the decline in productivity over 3 or 4 years of saved seed potatoes, so I buy fresh seed every other year. When the productivity goes down in my garden, however, it has meant fewer potatoes overall, not many, many small potatoes.
I saw this pattern again this year, when I harvested the 'Kennebecs'. There were fewer potatoes, but the distribution of size was normal. It was as if the crop of fingerlings was set and then did not grow out. Maybe fingerling potatoes lose productivity more quickly?
Other research suggested a delicate balance between not enough fertilization and too much. Like tomatoes, potatoes may grow a lovely drop of foliage and not set a great deal of fruit if there is too much nitrogen in the soil. The Andean farmers used copious amounts of compost and animal manures in their garden beds.
I toss handfuls of Down to Earth’s Biofish fertilizer underneath the rows before I plant. This, combined with the winter’s coat of leaves and a month of the Chicken Tractor, has always provided sufficient nutrients and organic matter for the potatoes.
The fingerlings looked good, but not falsely lush, while they were growing. The cucumbers at the end of the bed were thriving in the same soil, with the same water. All of the other potatoes had the same care and they were fine. I don’t think it was a fertilization issue.
Timing and Weather Considerations
I am wondering about timing and the heat wave we had in late April, just when the plants were flowering. The crop reminded me of my plum tree last year. Last spring was dry and warm early on — very unusual in the Pacific Northwest — just when the tree was flowering. It set at least twice, if not three times, as many fruits as it usually does, triggered, I believe, by the weather. The tree was covered in fruit, but it was all small, with larger pits.
This year, the weather was more normal during flowering and we had a normal amount of larger, plumper plums. The potatoes were setting tubers just when the heat wave hit. Temperatures were 10 to 15 degrees above normal for over a week.
Did the plants trigger a “lots of seeds, not much to eat” response, like the plums a year before? Maybe. If so, I might new some shade cloth to cover beds during early heat waves in the future.
Fortunately, I believe in crop diversity. Like the Andean farmers, I planted five types of potatoes, in three different beds. (I could not adjust for altitude like they did, however.) The others went in several weeks later and missed the heat wave’s impact. When I pulled them, harvests were excellent. Gardening is, at its heart, an Art and a Mystery, as well as a science. There are things we can know, and control, and things that we cannot. And I am constantly learning the difference.
Charlyn Ellis has been growing vegetables since she was five years old, when her mother bought her her first rake and pitchfork. She and her family are urban homesteaders and have a large organic vegetable garden, fruit trees, a beehive, four chickens, one rabbit, and two cats on a small urban lot in the center of town, surrounded by college students. Charlyn considers permaculture principles when she makes changes in her designs, especially the idea that the problem is the solution. Find her online at 21st Street Urban Homestead, and read all of Charlyn's MOTHER EARTH NEWS posts here.
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