Improve your garden by improving the soil

Having a good garden hinges on a lot of factors, including sunlight, water, and, of course, choosing the right plant for the place — and our relatively short growing season.

One thing that often gets overlooked but shouldn't is the soil.

Not only does it anchor your plants, it also holds and releases moisture and nutrients, and provides for the oxygen all flowers, fruits and vegetables need to grow well.

Improving the soil is a surefire way to increase your garden's yield. The best way to do that is to incorporate plenty of organic matter, such as compost, dried grass clippings or leaves, and well-rotted manure.

These materials can also do double duty by acting as summer mulch, which helps prevent weed seeds from sprouting, moderates the soil temperatures and slows the evaporation of moisture.

There's another bonus: Your garden soil will get better every year you add organic matter.

Adding organic matter can improve any type of garden soil.

Sandy soil doesn't retain water very well. Because moisture drains so rapidly, you have to water frequently to keep plants growing steadily throughout the summer. All that water washes nutrients deeper into the soil, where plant roots can't reach them. In sandy soils, organic matter acts like thousands of tiny sponges, helping hold both moisture and nutrients.

Heavy, clay-like soil is easily compacted by foot traffic. Even something as innocent sounding as raindrops or sprinkler water hitting the soil surface repeatedly will pack it down. When clay soil gets too dry, it forms a hard, nearly impenetrable crust, which interferes with moisture absorption. And, because the roots can't expand easily in compacted soil, plant growth suffers.

Incorporating organic matter into the soil can help. As it breaks down, it creates channels in the soil, which allow moisture to drain and roots to expand more readily. It also adds small amounts of nutrients to the soil, which the plants can access, and it allows the soil to hold more oxygen.

While it improves poor soils, organic materials help even excellent, loamy soil.

The prime times to improve your garden soil are in spring, before you plant annual flowers and vegetables, and in fall, after those plants are done for the season. Although our spring has gotten off to a late start, you can go ahead and work in some compost — either homemade or from a municipal composting site — any time now.

If you protected bulbs and perennials with leaves, straw, or grass clippings this winter, just rake them up and mix them into the soil. It's usually a good idea to add a little additional nitrogen, when you do so. Don't incorporate wood chips or shredded bark, though. As they break down over the summer, they compete for nutrients.

If you didn't mulch this winter, you can buy bagged manure, compost or peat moss at your local garden center.

Dry cubes of baled peat cost more initially, but they're a better value than plastic bags of moisture-laden peat. To use, simply spread the dry peat in a 1- to 2-inch layer over the soil, then dig it in well.

You can make your own compost at little or no expense, and keep yard waste and kitchen scraps out of landfills at the same time.

Grass clippings, leaves, prunings from plants, along with vegetable plants that are no longer productive, and flowers, herbs and vegetables that are frost damaged and wilting all make great compost. Add scraps from food preparation, such as trimmings and leaves from lettuce, carrots, corn or other vegetables, citrus rinds. Don't include fats, oils or meat scraps. They attract rodents.

You may have read that it's OK to use wood ashes from your fireplace or fire pit. If you do, add them very sparingly. Wood ashes make the soil more alkaline. When used heavily, they tie up nutrients in the soil, making those nutrients unavailable to your plants.

Deb Brown is a garden writer and former extension horticulturist with the University of Minnesota.