Best Fertilizer For Potatoes


Staff member
When planting potatoes I start out with 13-13-13. This is a well balanced fertilizer that I feel helps get the plant established.

Around six weeks after planting I side dress with 10-20-10 and then work up a mound around the plants.

  • 13-13-13 - well balanced for plant growth
  • 10-20-10 - helps promote tuber growth

Before side dressing watch the weather very closely as I want a nice rain after side dressing. The rain helps wash the fertilizer into the soil.

A couple of weeks later I typically work the soil up around the plants. I usually do this by hand, but in 2019 I will use the tractor. Planning on planting a large garden and need to conserve time when I can.

Around May or June the tops of the potato plants start to die, so the potatoes are harvested.

What about something like 21-0-0? That is a high nitrogen fertilizer that provides very little for tuber growth.

Let's break the fertilizer numbers down.

  • First number, nitrogen - Promotes large leaf growth. This is what greens and corn would need to grow big and tall.
  • Second number, phosphorus (P), aka bonemeal - Promotes root growth. This is what grows the potatoes.
  • Third number, potassium(K), aka potash - This promotes the growth of pods, as in beans and even corn.


16-6-12: Large leaf for growth, little for root, and pod production.
21-0-0: Grass, long leaf with nothing for anything else.
13-13-13: Well balanced for a wide variety of crops.
10-20-10: Root / tuber growth. this would be excellent for potatoes.