The Iowa Gardener: Does your garden have a good foundation?


Soil organic matter provides plants with the nutrients they need to thrive

Adding organic matter to your soil regularly each year helps keep your plants thriving. (Dreamtime/TNS)

If you’re like me, you spend a lot of time and money on your garden. But just like a house, the most money and energy you can spend is on the foundation. And the basis of a garden is the soil.

It is important to add organic matter to the soil each year. Repetition: every year. You don’t have to add organic matter to all of your planting areas every year, but you should practice regularly – throughout the gardening season – mulching it, digging in open areas and add each hole or planting area to it. .

If you don’t, all those pretty, delicious plants will suck nutrients out of the soil and you’ll have less healthy, less productive plants every year.

Synthetic chemical fertilizers can help, but it’s like putting a few braces in a sagging foundation. Only adding organic matter can really help your soil continue to be the strong foundation your plants need.

Organic matter provides not only major nutrients, but also micronutrients. It changes the texture of the soil so that it can retain moisture when conditions are dry and flow freely when conditions are wet. It makes the soil loose and crumbly so that weeding is a breeze. It attracts earthworms, which aerate the soil with their tunnels and further enrich it with their “casts”, a fancy term for worm poo.

What is organic matter? Basically any type of plant material that breaks down over time, usually after a year or two. The soil under three old crabapple trees in my side yard was incredibly rich and crumbly because there were crabapples rotting for 50 years.

Some of the best types of organic matter:

  • Compost. These are plant materials (leaves, grass clippings, kitchen scraps, coffee grounds, weeds, manure and just about anything else) that have already been “pre-rotted” so that the plants can immediately take advantage of its many benefits. You can buy it in bags or have a pile delivered by a landscaping service, but it’s much cheaper and more environmentally friendly to make it yourself in at least one and up to three or four piles of compost in your garden.
  • Grass clippings. As long as they haven’t been recently treated with a weed killer (which can kill other plants), they’re great for digging into the ground or spreading on the ground as mulch. Dig into the ground at the end of the season or the following spring.
  • Autumn leaves. Toss them in a compost heap or mash them up with your mower (and scoop them up in the bag) to put them in the compost heap or use as mulch. Or in large open spaces, such as vegetable gardens, dig directly into the ground.
  • Sphagnum peat. It is a dried, chopped form of moss that is excellent at retaining moisture. But like all organic matter, it also eventually breaks down, nourishing and improving the soil.
  • Manure. Manure from herbivorous animals (cattle, chickens, horses) is essentially made up of plants that have decomposed in the animal’s intestinal system. But don’t use manure or feces from carnivorous animals (cats, dogs, etc.) as they can harbor unhealthy pathogens. Also, don’t put fresh manure on the plants because it contains too much nitrogen. As a general rule, allow manure to sit/compost about 6 months before using it around plants.
  • Wood chips and wood or bark mulch. Wood chips can be used as a mulch, but should age/compost for about 6 months to a year before applying around plants. Fresh wood chips, as they decompose, deprive the soil and plants of nitrogen. This is not a problem with the wood chip mulch you buy in bags since it has already aged.
  • Straw and hay. You can use it as a mulch in certain areas, such as vegetable gardens. But it’s also high in seed, so use it only in areas that you can easily till or hoe thoroughly once or twice per growing season and that will otherwise be heavily mulched to suppress unwanted growth. Dig or cultivate it into the ground at the end of the growing season.
  • Cover crops. These are nutrient-dense plants (like clover, rye, and buckwheat) that you sow in the ground, let grow for a while, and then grow, incorporating all that organic matter and its nutrients. Ideal for large vegetable gardens and other large, easy-to-grow spaces.

Veronica Lorson Fowler is co-editor of the Iowa Gardener website at


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