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

Regularly adding organic matter to your soil each year help ensures that your plants will thrive. (Dreamstime/TNS)

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

It’s important to add organic matter to the soil every single year. Repeat: Every single year. You don’t have to add organic matter to all your planting areas every year, but you should make it regular practice — all garden season long — to mulch with it, dig into open areas, and add to it every single planting hole or area.

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

Synthetic chemical fertilizers can help, but they’re like putting a few reinforcements into a sagging foundation. Only the addition of organic matter truly can help your soil continue to be the solid foundation that your plants need.

Organic matter not only provides major nutrients, it also provides micronutrients. It changes the soil texture so that it can retain moisture when conditions are dry and drain freely when conditions are wet. It makes the soil loose and friable so that weeding is a snap. It attracts earthworms, which aerate the soil with their tunneling and further enrich it with their “castings,” an elegant term for worm poop.

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

Some of the best types of organic matter:

Compost. This is plant matter (leaves, grass clippings, kitchen waste, coffee grounds, weeds, manure and just about anything else) that has already been “pre-rotted” so that plants can immediately take advantage of its many benefits. You can buy it in bags or have a pile of it delivered from a landscaping service, but it’s far cheaper and more earth-friendly to make it yourself in at least one and as many as three or four compost heaps in your yard.
Grass clippings. As long as they haven’t recently been treated with weed killer (which can kill other plants), these are great to dig into the soil or spread on top of the soil as mulch. Dig into the soil at the end of the season or the following spring.
Autumn leaves. Toss these into a compost heap or run over them with your mower (and collect them in the bag) to put in the compost heap or use as a mulch. Or in large open areas, like vegetable gardens, dig directly into the soil.
Sphagnum peat moss. This is a form of dried, chopped moss that is excellent for retaining moisture. But like all organic matter, it also eventually breaks down and feeds and improves the soil.
Manure. Manure from plant-eating animals (cattle, chickens, horses) is essentially plants that have broken down in the intestinal system of the animal. But don’t use manure or droppings from meat-eating animals (cats, dogs, etc.) since it can harbor unhealthy pathogens. Also don’t put fresh manure on plants because it contains too much nitrogen. Generally, allow manure to sit/compost about 6 months before using around plants.
Wood chips and wood or bark mulch. Wood chips can be used as mulch, but they must be allowed to age/compost for about 6 months to a year before applying around plants. Fresh wood chips, as they breakdown, rob the soil and plants of nitrogen. This is not a problem with wood chip mulch you buy in bags since it’s already aged.
Straw and hay. You can use this as a mulch in certain areas, such as vegetable gardens. But it also contains a lot of seeds, so use it only in those areas that you can easily till or hoe completely once or twice a growing season and which will be otherwise heavily mulched to suppress unwanted growth. Dig or till it into the soil at the end of the growing season.
Cover crops. These are high-nutrient plants (like clover, rye, and buckwheat) that you sow into the soil, let grow for a period of time, and then till under, incorporating all that organic matter and its nutrients. Best for large vegetable gardens and other large spaces that are easy to till.

Veronica Lorson Fowler is co-publisher of the Iowa Gardener website at www.theiowagardener.com.