Saturday, April 5, 2014

Using Potato Grow Bags in Colorado by Ellen Goodnight


I will be the first to confess that I am not an expert potato grower. Further, I will admit that I have tried to grow a variety of potatoes, in all sorts of conditions and places in my gardens, with varying degrees of success. Moving to another house set a new challenge as I wanted to grow my beloved potatoes along with every thing else in a rather limited space. Potato plants can easily take over a garden.

I began to to look at alternatives and read about using large fabric bags. Would these really support large potato plants and would I get the kind of yield the advertisements promised? Did I really need to buy the special soil mix and fertilizer the catalog recommended? My potatoes had always grown in well-composted garden soil and done very well. I was  starting to have my doubts about the expense of growing in bags but  I decided to take a gamble.

I bought two large fabric bags, and one bag of the special soil mix and fertilizer. I wanted to compare the yield results of using the soil/fertilizer mix  in one bag and using garden soil mixed with my own compost in the other. I planted Red Norland, Russett and Yukon Gold seed potatoes in the bags in early April.

Two weeks later, I began to see potato sprouts breaking the surface. As time went on, I did notice that I did not have as many sprouts as in the past, but what I did have seemed to be doing okay. I was able to keep the bags moist with my hand watering and the rain we were getting. By late June, the plants had started to vine and set blooms.

As the summer heat increased, I was having to water more often to keep the soil moist in the bags: Sometimes two and three times a day. I also noticed that the plants did not look as vigorous while some were starting to brown out. By mid-July some of the plants had withered and died. The blooms were gone, so I started to feel in the soil for potatoes to rob. No potatoes. I began to suspect that my yield was not going to be very high, but decided to wait until the end of July to harvest.

Harvest day came by emptying the bags to find very few potatoes. Out of 24 seed potatoes pieces, I harvested 14 potatoes, in the mid- to small-size range. Most of the potatoes were in the center of the bag. There were some plants that did not even produce potatoes. I also noticed that the root development of the existing plants was not very extensive –  potatoes grown in the garden tend to to have roots that spread out well beyond the main stalk..

My experiment led me to decide that growing potatoes in fabric bags in Colorado was not a good idea most likely because our climate is too dry. I made the following conjectures:
  • The fabric bags are too porous for our arid climate, allowing the soil in them to dry too quickly.
  • This made maintaining consistent soil moisture difficult.
  • The plants did not develop extensive root systems for potatoes to develop  because of a lack of water. I came to this conclusion since the few potatoes that did develop were in the center section of the bag where the soil was somewhat more moist.
My test between the soil/fertilizer mix and my garden soil mixed with compost did not prove anything. I saw no difference between the two bags in seed potato sprouting, vine growth or potato production.
Maybe growing potatoes in bags in a more humid area with greater rainfall would make a difference. For now, my seed potatoes will be growing in my garden beds.