New garden soil test--elevated P & K - Ask Extension
I put a new garden in this fall, brought in a truckload of soil from the garden center, tilled it in, sent a sample to UMN for testing. The phosphoru...
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New garden soil test--elevated P & K #922079
Asked November 17, 2025, 2:41 PM EST
I put a new garden in this fall, brought in a truckload of soil from the garden center, tilled it in, sent a sample to UMN for testing. The phosphorus and potassium numbers that came back are very high. What should I do? I've seen articles about cover crops, but I don't know what amendments to make. Attached are the test results.
Sherburne County Minnesota
Expert Response
It depends on what you are growing in your garden. If it is flowers, the soil may be okay because P and K promote blooms. Otherwise, do a cover crop and till it in come Spring. Check the nutrient needs of the plants you want to grow. You may need to add nitrogen only fertilizer (lawn fertilizer) for vegetables. See the Tomato example in the following web page. Your organic matter is okay for now. If you add more, you may be inadvertently adding more P and K to your soil.
https://extension.umn.edu/manage-soil-nutrients/quick-guide-fertilizing-plants
https://extension.umn.edu/yard-and-garden-news/you-might-be-over-fertilizing-your-garden
https://www.aces.edu/blog/topics/lawn-garden/excessive-phosphorus-in-garden-soils/
https://extension.umn.edu/manage-soil-nutrients/quick-guide-fertilizing-plants
https://extension.umn.edu/yard-and-garden-news/you-might-be-over-fertilizing-your-garden
https://www.aces.edu/blog/topics/lawn-garden/excessive-phosphorus-in-garden-soils/
