Plants Need Potassium

Potassium is associated with fruit quality in many vegetables. In tomatoes potassium helps the plant produce high quality, deep red fruits.

The only way to know if your soil has enough potassium in it is to get a soil test. If your soil test results indicate you need potassium there are several good sources. One source is to purchase a fertilizer containing potassium. Potassium is the third number listed in the fertilizer analysis. When buying fertilizer that only contains potassium it is typically sold as 0-0-60, which means that fertilizer is 60% potassium. If the fertilizer analysis is 5-10-5 then it contains 5% potassium. Other sources of potassium are wood ash, compost or manure.

The principal nutrients in wood ashes are: potash (3-8%), phosphate (1-2%), calcium (20-25%), and magnesium (2%).  Wood ashes also contain numerous trace elements.  Both the potash (which supplies potassium) and the phosphorus are highly available to plants.  The liming value of wood ashes is also notable.  In calculating the value, figure that it takes 1 1/2 pounds of wood ashes to equal the neutralizing power of 1 pound of ground limestone. 

For more information contact your local extension office. In Lackawanna County call 570-963-6842 or email LackawannaMG@psu.edu

John Esslinger, Extension Educator
Penn State Cooperative Extension