A Question of the Week

hand holding soil

I got my soil tested and the results show I need lime, Nitrogen and Potassium. Can I add those amendments to my vegetable garden in the fall or should I wait until spring?

Fall can be a good time to get your soil tested, and one reason is that you will have results in hand well before spring and can plan accordingly. Soil test results may not specify when to apply recommended amendments and that can be a source of confusion for those who get their soil tested in the fall.

Even if choosing slow-release sources of Nitrogen and Potassium, fertilizer should be applied to the vegetable garden in the spring. In most New Hampshire soils, amendments containing Nitrogen and Potassium will leach through the soil rather than remaining available in the soil for next year’s garden.

That said, there are some amendments that should be applied in the fall. One example is agricultural limestone, which is used to raise the pH of acidic soils to a range suitable for what you’re trying to grow. When pH is within a suitable range, it’s easier for plants to access the nutrients in the soil and from fertilizer applied during the growing season. Lime works slowly, and applying lime in the fall allows time for the necessary chemical reactions to take place in the soil.  

Sources of organic matter, such as compost and manure, can also be incorporated in the fall with a rototiller or broad fork. These amendments would only be recommended if your soil test results show low levels of Phosphorus and organic matter content. If your organic matter content is low and your Phosphorus levels are high, consider using a fall cover crop such as oats that will hold soil and nutrients in place until spring.

Do you love learning about stuff like this? 


A monthly newsletter for New Hampshire gardeners, homesteaders and plant-lovers of all kinds, that includes seasonal suggested gardening tips, upcoming events and articles with proven solutions for your garden and landscape.

Got questions? The UNH Extension Infoline offers practical help finding answers for your home, yard, and garden questions. Call toll free at 1-877-398-4769, Monday to Friday, 9 a.m. to 2 p.m., or e-mail us at answers@unh.edu.


Extension Field Specialist, Community & Economic Development
Phone: (603) 678-4576
Office: Cooperative Extension, Nesmith Hall Room 204, Durham, NH 03824