Civic organization - growing petunias

Asked September 11, 2014, 4:17 PM EDT

Our local volunteer civic group plants 30,000 petunias along the streets, boulevards, and marina area each year. There are 35 "blocks" altogether. Since we are on the shore of Lake Michigan, there are many soil types, from sandy to clay to heavy dark soil. Our question is, how many soil samples will this require, and will this process be cost-prohibitive, since we are totally supported by donations? Also, salt from the streets during winter months is a factor. Suggestions?

Mason County Michigan

1 Response

There is not any way that you can pull that many samples at $25 apiece and then fertilize them all separately. You might be better served by buying a fertilizer in bags like 6-24-24 which has more phosphorus and potassium for blooming plants and applying lightly. Nitrogen, the first number, does not need to be big. This could work for annuals because you just have them one year. It would be much more difficult if these were perennials.

As to the salt, it could change soil pH so look at how plants are doing or grass is doing in areas. If there is poor growth, salt might be a contributor... or not. A test for soluble salts would add to the cost of a soil test and would only be used if there were places where it was difficult to get anything growing. The only thing that removes salt from soil is time and a great deal of water to flush it through.