I'll be completing my sixth and final application of postassium this week. The canes on my roses are a beautiful dark red; all hardened off for the cold weather to come.
Someone in the U.K. who read my blog raised a valid question on a garden chat site about the level of chloride (salt) being applied to the beds with Muriate of Potash and suggested that perhaps Potassium Sulfate would be a better form of potassium for the roses. That's a good idea and I will be looking into the availability of Potassium Sulfate next year, if for no other reason to add a little sulfur to my soil.
However, in reality, the level of salts being applied with one tablespoon of Muriate of Potash per three gallons of water is quite small and well within good soil management limits. Here is an excerpt from an e-mail I exchanged with Dr. Peter Bierman, Professor Emeritus of the University of Minnesota Soil, Water and Climate Department, in February 2011:
" I agree that winter hardiness is one of the most important functions of potassium. The rate you quoted would be about 0.1 lb K2O per plant per year. U of M recommendations for a flower garden for a soil testing low in potassium is 0.4 lb K2O per 100 sq ft., which would be close to that recommendation. So even if your soil tested high in potassium it would be a reasonable amount to apply for winter hardiness insurance and wouldn't be an excessive amount in terms of adding high salts."
Bottom Line: The "Potassium Feast" has worked for me for 20 years without a problem and falls well within the limits of good soil management.
I would enjoy hearing from others who have tried the "Potassium Feast" this year. E-mail me: firstname.lastname@example.org .