Trott column: For healthy plants, start with the soil

Here's how to test your garden soil.

Robin Trott
Robin Trott

I spent a glorious Easter sitting under our trees with kittens on my lap and the birds singing overhead! Spring has sprung, (although the forecast for this week looks kind of glum), and many gardeners have asked what chores they can accomplish in their yards and gardens prior to spring planting.

One of the top springtime questions I often get is how and when fertilizer should be applied. It is a difficult question to answer without information on the soils in the garden or lawn. Adding fertilizer or organic material to your garden spaces can be labor and cost intensive, and applying just what your garden needs at the right time will save you time and money. Here are some guidelines you might consider when amending your soil this spring.

Now is a great time to have your soil tested. Most home yards are disturbed soils, a mixture of top and subsoil caused by the construction of your home. This mixing of soil means that the soil in your yard may be quite different from that of your neighbors.

Soils contain the nutrients and minerals necessary for your plants to grow. Over time, these essential elements can become imbalanced or depleted. Taking a soil test will help you learn what nutrients are available to plants. My advice would be to do several tests, one in the front yard and another in back. A third area to test would be garden areas where you are growing flowers or vegetables. Normally doing a test every five years should be adequate, unless you see nutrient problems developing in areas.

Soil tests can be no better than the sample. Therefore, proper collection of the soil sample is extremely important. To obtain a good soil sample, follow the directions below.


Where: If the area is fairly level and the soil appears to be uniform, collect a composite (mixed) sample. If your lawn or garden has large areas which differ in fertility, take one sample from each area. For example, you may want to sample the front lawn and the back lawn separately. Do not include soil from the lawn area and a garden in the same composite sample

How: Use a garden trowel, spade, sampling tube, or soil auger. Scrape away or discard any surface mat of grass or litter. Sample the lawn or garden area to the correct sampling depth and place the soil sample in a clean bucket or pan. Repeat sampling in five scattered spots within the chosen area. Mix soil well to make a composite sample and send in about a pint of the sample to the laboratory.

Visit to watch Extension Educator Katie Drewitz of Stearns/Benton/Morrison counties review how to collect samples to submit a soil test.

If you are not interested in having your soil tested this year, there are some things you can do to improve the health and fertility of your soil. Adding compost to your garden is always a great start. Compost contains organic material which increases soil nitrogen, lightens heavy clay soils, and increases water retention in sandy soils. If you don’t have access to compost, bags of peat moss and composted manure can also be used to improve your soil. (Always use composted manure. Raw manure will burn plant roots and damage and weaken plant material.)

Once your soil bed has been prepared, you are ready to plant. Your garden, rich in essential nutrients and minerals, will give plants a great start!

Until next time, happy gardening!


“So, friends, every day do something that won't compute...Give your approval to all you cannot understand...Ask the questions that have no answers. Put your faith in two inches of humus that will build under the trees every thousand years...Laugh. Be joyful though you have considered all the facts....Practice resurrection.” — Wendell Berry, "The Country of Marriage"


Robin Trott is a horticulture educator with University of Minnesota Extension. Contact her at 320-762-3890, or at

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