MASTER GARDENERS: Fall is the best time to test soil

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Does anyone else have a rough garden plan written out for the 2021 season? Think about this activity now.

As our gardens head into the fall season, it is time to think about testing our soils for next year’s garden. If you wait until spring to test your soil, you are likely to have a longer wait to get your results back and you will not have as much time to plan changes to your soil. And it is hard to collect a soil sample during a Minnesota winter.

Master Gardeners are always going to recommend soil testing with the University of Minnesota soil testing laboratory. Their web address is . You will find everything you need to know on that site. There are home soil tests available, if you like, and you may find private soil testing companies, but the University will give you results and recommendations adapted to our region in Minnesota.

When collecting a soil sample make sure you follow the soil lab recommendations. It must be representative of your garden and be taken from the top layer of soil. Use clean tools and a clean bucket to take samples from different areas and then mix them together. Keep away from any fertilizer source. Allow it to air dry and then place it in a plastic bag in a box for mailing, indicating what type of gardening you are doing -- vegetable, perennial, turf, etc.

Soil testing isn’t for everyone. The lawn and garden test will cost $17 and the postage will be about $8. If you are short on gardening budget, you may be better off buying a $25 bag of fertilizer with nitrogen, phosphorus, potassium and additional micro nutrients to apply next spring.


A good test for how good your soil is can be done visually. If the weeds and grass are tall, you already have a good fertile soil. Poor growth of weeds and grass may be an indication of low soil fertility or it may be poor drainage or low organic matter.

I haven’t always been a fan of soil testing. Nitrogen is not tested at the University of Minnesota. The nitrogen recommendations are based on soil organic matter and the needs of the crop you are growing. Most gardeners are going to add fertilizer regardless of the soil test.

You should test your soil if you want to take your gardening to the next level. I tested my soil last fall and I found some useful information. I now know that my soil has a pH of 6.9, which is right at the upper limit for most vegetable crops. I know that I don’t want to add lime or calcium to my soil and I don’t have to worry about using acid (vinegar solutions) to control weeds.

Developing a really good garden soil is a long-term process. You can buy bags of soils that will give you a great jump start in your garden venture and you can buy a truckload of fantastic Red River Valley topsoil, but soil formation takes time. Good soil is full of microorganisms that take time to develop and adapt to your precise location. Abrupt changes in soil texture can interfere with water movement in the soil. Soil is complicated!

These local garden articles will reach you each week throughout the gardening season, but also click on "Yard and Garden” at the University of Minnesota Extension website -- -- for gardening information, or visit our Facebook page at .

Local Master Gardeners will respond to questions via voicemail. Call (218) 444-7916, and leave your name, number and question.

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