Voles, sometimes called meadow mice, really like potatoes. If you’ve grown potatoes for any amount of time at your place, it’s a good chance the voles have discovered them and moved right on in. Before I grew so many cover crops, I mulched everything with leaves. Voles love the cover of mulch, happily going about their business (of eating potatoes) out of the reach of predators. As much as I loved mulching the potatoes with leaves, or anything else, I had to stop that practice.
It turns out that voles also love living among the grain crops. More than a decade ago I gave up the leaves in favor of cover crops. I’ve been doing some great soil building and the voles appreciate every bit, living among the roots of the grains while they’re growing and when the roots are decomposing in the beds. I’ve changed up the preceding cover crop for potatoes, first with Austrian winter peas and now with oilseed radish. The winter peas were wonderful, leaving the bed friable and able to be worked by April 1, pulling out the green pea plants for the compost pile, but I still had vole problems. I was betting on the oilseed radish. After all, it’s a brassicus and potatoes and the cabbage family are supposed to be friends. Voles also love radish and their holes were evident through the winter where they’d feasted. One advantage of that is that I set traps and caught a few before the potatoes went in.
I figure maybe I’m supposed to have vole problems, so that I can work on balancing that part of the ecosystem and give you some advice. This year I decided to address the vole problem head on. I scoured the Internet for suggestions and came up with a few to try. Adding greensand to the bed should help, said one source. I’m a little short on potash in my garden anyway and so I added greensand to every potato bed. Bury elderberry stems with the potatoes, said another source. Drop in some crushed oyster shells when you plant, urged my friend. Crushed oyster shells are something you can buy by the bag and are often used as a calcium supplement to feed to chickens. I planted potatoes six different ways to test all the ideas.
I already knew that varieties make a difference and that the voles love the yellow fleshed ones more than anything, which is why I had long since given up growing Carolas, my favorite variety. One year when I did grow Carola potatoes, I also had Butte at one end of the bed. I remember that the voles took out the Carolas and slowed down considerably when they came to the Buttes. My choices for 2012 were Kennebec and Butte. As it turns out, they love Butte more than Kennebec. In my trials, the Kennebec yields were 1.6-2.6 times higher than the Butte yields, with the same planting methods.
Adding elderberry to the plantings interested me, and we have elderberries growing at our place, so that was easy. I put elderberry leaves on top of each potato piece and buried green elderberry stems between the rows. That bed gave me the worst yield of all, resulting in 6.4 lbs/100 ft² for the Buttes and 17.2 lbs/100ft² with the Kennebecs. Remember we make no mistakes, only learning experiences. I learned not to try that again.
One thing I had an interest in trying is to put a post in each potato spot with a plastic bottle on top to bang around and make vibration. I used old metal posts, the kind used for electric fence, for some of the posts and bamboo for the rest. I cut “wings” in the sides of the plastic bottles and cardboard milk cartons that I put on top of the posts, hoping the “wings” would catch in the wind and vibrate the posts, making conditions uncomfortable for the voles. Even rain should have caused some vibration. I learned that was nothing I need to try again, also. Dealing with the posts and bottles were a lot of bother, anyway. In that bed, I had a row of potatoes down the middle of the bed and I hilled around each one. On one side I set out cabbage when the potatoes were planted. The other side had snap beans, planted after some hilling had been done to the potatoes. Another year I had interplanted potatoes and cabbage and the voles took out the potatoes. Interplanting potatoes and brassicus is officially off my to-do list.
Oyster shells seemed like a logical thing to do, reasoning that voles don’t like the rough surface, but I had tried that before. If it had worked as well as I’d hoped, I’d still be doing it. Besides, my soil didn’t need more calcium. However, my friend said he had good luck with that and urged me to try it again. I did, putting a handful of crushed oyster shells in with each potato piece, then soil, then shells, then topping with soil. Only Buttes were planted in that bed with a yield of 24 lbs/100 ft². Oyster shells are officially off the list of things to do again, also.
I built a new 4’ x 8’ coldframe this spring. I dug everything out to about 15” and put ½’ hardware cloth in the bottom. Then I built the sides with dry-stacked solid cement blocks, topping that with a wood coldframe, right out of Eliot Coleman’s Four Season Harvest. Although I needed it to grow seedlings, I wanted to first try it as a potato planter. I only had Kennebecs in there for a yield of 43 lbs/100 ft². I still found vole tunnels in this planting. The voles could have crawled in over the top (an edge sticking out from the coldframe all around might have prevented that) or may have gotten through a crack where the cement blocks may have shifted. Still, I had potatoes. Things were looking up.
In one bed, I tried a variety of things. I buried large black plastic pots with the bottoms cut out, each with 2 potatoes; 2’ high circles of ½” hardware cloth dug into the ground about 10”, each with 3 potatoes; and potatoes planted loose in between these barriers. The Butte half of that bed yielded 35 lbs/100 ft² and the Kennebec yield was 71.8 lbs/100 ft². At the end of that bed I had built a planter, laying hardware cloth on the ground and making a surround 3 bricks high, filling it with soil. Into that I put 4 potatoes. Granted, it was a very small area, but the yield was 98 lbs/100 ft²! After fighting the voles for years, friends of mine had done something similar to grow their sweet potatoes in, with success. I would have thought the voles would just climb over the bricks to get in, but maybe they like to stay close to the ground.
I usually space my potatoes equidistant, every 12”, but with the vole problems, I thought I might be making it too easy for them to go from one to the other. This year, in one 4’ x 20’ bed I put just two rows of 20 potatoes in each row, hilling each plant separately. The Butte half yielded 18.25 lbs/100 ft² and the Kennebec half gave me 30.25 lbs/100 ft². Comparing the Kennebecs in the hilled rows and the ones in the brick planter, 30 pounds is a lot less than 98 lbs. per 100 ft², but just about the same yield per plant. I could increase the yield in that bed with hilled rows if I interplanted something after the potatoes were hilled for the last time and if I was more aggressive about trapping voles early. The interplanted crop would have to be ready to come out with the potatoes.
Our daughter, Betsy, Lightfoot Gardening Coach, and I have been exchanging notes on potatoes. This is her second year in a garden that she carved out of a field, double-digging the beds when she started. She had planted oats and oilseed radish in her beds preceding potatoes. Since we had such a mild winter, she had to chop the oats in and let that crop compost in place. She pulled the radishes for the compost pile. In “normal” years, if there is such a thing, those crops would have winter killed. She planted Elba potatoes and in the oats bed, with the potatoes planted intensively with offset spacing, she harvested 107 lbs/100 ft². In the radish bed she planted two long rows and hilled each row 3 times. Her yield there was 90 lbs/100 ft². Planting it that way, she used only about half the potatoes and came close to the same yield. She also noticed that the hilled Elbas were larger than those planted intensively. She planted Red Norlands in a bed that had oilseed radish over the winter. It was treated the same way as the hilled Elbas. There was lots of vole damage, producing a yield of 50 lbs/100 ft². She had noticed vole damage during the winter in her radish cover crop and had worried about this year’s potato harvest. She did okay, with bushels of potatoes for her larder.
One good thing about keeping records is that it helps in planning for next year. I will continue working with Kennebec potatoes and will compare them to Betsy’s Elbas. I might grow a radish cover crop and trap the voles through the winter, something I should have worked more on this year. I’m going to be looking at different preceding cover crops and planting in hilled rows with space for possible interplanting on the sides. Although I don’t like to do much cultivation, I think regular cultivation and hilling helps deter the voles. Hoping to develop an ecosystem that makes the voles stay away voluntarily, I’ve been adding daffodils to the perimeters of some beds (have yet to see that as effective) and have added castor plants to the garden. In the end, it will be everything together that determines success—variety, planting and cultivation, soil fertility, weather, etc. Wishing you success in your potato endeavors. Do you have any potato/vole experiences you would like to share?