Q. Dear Peter, We live in Graham and love to raise our own potatoes because they are fun to raise and taste better than the ones from the store. However, we got a lot of potatoes last year that are hollow and dark or rotted in the middle. We planted Kenebecks’s last year and the year before we planted Yukon Gold and had the same problem with them. The smaller to medium potatoes don’t have as much of a problem; however we can count on the huge to larger ones to have the problem in each one. Is it something with the watering, or perhaps the soil? We have a nice sandy soil, which was a 5-way garden mix we ordered for the raised garden bed. We have a water softener and the garden gets watered with the softened water because we don’t make a habit of going in and changing over the softener to regular water when watering the garden. We would like to plant potatoes again this spring, but it is disheartening to lose so many to this problem. We also like to share our garden with friends and family and it is embarrassing to give them something that is bad when you can’t see it. Sincerely, Yvonne Fullerton – Graham, WA
A. Oh yeah, there are so many tasty potato varieties available and their numbers completely dwarf the varieties available commercially in the grocery stores. The condition you are describing is called Brown Center and/or Hollow Heart. These are two descriptions of a physiological disorder caused by the same conditions. Hollow Heart is a more advanced expression of the disorder. So there is no pathogen or insect involved. It seems that when potatoes are grown in a cool moist soil some cells can die off in the center of the forming potato (I think they call this moisture stress). Then if this period is followed by a warm period and quick growth this brown center can separate causing a hollow center. That sounds just like our weather – cool and moist in the spring and then nice and warm once the sun comes back out. It shows up more on larger potatoes because their relative growth is more rapid than smaller varieties. Even if some cells die in the center of a small potato they don’t usually separate and can actually move and disperse as the potato grows. Now you know that some of the varieties you are using are susceptible to this condition. Try other large varieties especially if they are listed as resistant to Brown Center / Hollow Heart. Another recommendations often made is to use larger potato “seeds” (the starter tubers are called seeds). This strategy probably gets the tubers past their vulnerable stage. As far as your using softened water you should be aware that softening replaces magnesium and calcium ions (both plant nutrients used by plants) with sodium (which is not a plant nutrient). Salt can build up in the soil and can interfere with plant growth if levels build up (remember the Romans and Carthage?). But since you have sandy soil the buildup may be negligible, but it is good to be aware of this. Try not to be too embarrassed about your less than perfect potato gifts. They are still edible. Did any of your friends and relatives grow their own gifts?