Mulch is a key to no-till gardens

Photo of leaves.
Leaves make excellent mulch for no-till gardens, as shown in this enclosed garden bed of bok choy. (Photo by EESC.)
Last Updated: 
September 7, 2012

CORVALLIS, Ore. – Now is the time to plan your no-till garden for next year. 

"The crux of no-till gardening is to pile on enough mulch so that weeds don't germinate and grow up through it," said Barb Fick, a horticulturist with the Oregon State University Extension Service, who has kept her large vegetable garden viable with the no-dig method for years.

To establish a new no-till garden in the fall or winter find a sunny spot and outline where the new beds will be. Use a garden hose or rope if the borders are curved. Because you won't be tilling, you won't need to confine your garden design to straight lines.

Be sure to lay out the vegetable beds so that you can easily reach any part of the bed from a path while kneeling. It's important not to step into the bed and compact the soil. If you put your new no-till garden into an existing lawn and want the paths to remain as grass, don't forget to make them wide enough for your mower.

After that, start heaping on the mulch. Fick prefers to pile on aged mint straw in the fall.

"Whatever you use, don't skimp on mulch," she said. "A heavy layer not only keeps weeds from growing, it also keeps the underlying soil moist, greatly reducing the amount of watering you need in the summer."

If you use leaves, grass clippings or straw, you might need as much as eight to 10 inches of them, Fick said. If you use cardboard or newspaper as mulch, you'll need less of it, she said. You'll want to add a couple of inches of organic matter over it though.

Over time, the mulch layers you keep adding will help loosen up the clay soil. The soil formed by the addition of so much organic matter will likely be loose, full of earthworms and teeming with healthy microbes that make nutrients available to your plants.

When you're ready to plant in the spring, push aside the mulch layer where you want to put your seeds or transplants. For the first year or so, you may need to dig out old roots and add topsoil or compost in the hole where you want to plant. An advantage to no-till is that you turn over a small amount of soil only where you'll plant seeds or starts. This keeps old weed seeds down in the soil, making it harder for them to germinate.

If you're growing large transplants like melons, tomatoes, eggplants and peppers, in the spring you can lay down heavy black or red plastic to warm up the soil faster, conserve moisture and reduce weeds. One caution though: depending on its weight, plastic sheeting eventually breaks up into tiny pieces as it deteriorates from exposure to the sun. Soaker hoses or drip irrigation – the best ways to water a no-till garden – should be placed under the plastic.

As your crops come to an end, incorporate the dead vegetation into the mulch. 

"Adding organic matter or mulch is the best way to insure a healthy garden," Fick said. "If the prospect of a vegetable garden blanketed under huge mounds of organic matter or mulch doesn't fit your vision of a perfectly tended garden, remember that when soils bake in the sun, weeds grow and plants become dehydrated and die." 

For more gardening tips from the OSU Extension Service, please visit the gardening page.

Author: Tiffany Woods
Source: Barb Fick