Mulch - It does the Garden Good

Peony petal mulchPeony petal Mulch.  Photo by Ken Lockwood.

Ingrid Estell gardens at the Northside Community Garden and participates on our leadership committee. We are lucky enough to have her guest blog for Community Gardens once a month!  This blog post originally appeared as an article in the July 2013 issue of The Regular Joe which you can pick up at the Northside Community Garden.


First, let’s talk a little about watering. Almost all vegetable plants need to be watered in the greater Missoula area. Watering can be accomplished by soaker hoses, flood irrigation, or overhead sprinklers. Overhead sprinkling, which most of us use, is the least efficient as you lose water to evaporation, especially on a hot, sunny day. And if you soil is bare, no matter what watering method you use, the water will evaporate quickly in the sun. So, cover the dirt!

Cover the dirt with what, and how? Straw, grass clippings, and chopped leaves work well as mulch around your plants. Wood chips or sawdust are great for paths, but don’t get the wood material close to your plants. As the sawdust and wood chips decompose (yes, decomposition is taking place in your garden all the time!) they tie-up nitrogen in your soil and your plants “starve” or at least struggle to grow and produce or flower. You can also use pulled weeds for mulch, just make sure the seed heads haven’t developed and the roots are placed off the dirt. I often use trimmings from plants to mulch. When my grape hyacinths are done blooming, I cut them back and use their trimmings for mulch. You can go nontraditional: I like to mulch small areas with peony petals. I also often mulch with dill, feverfew, and lemon balm – all plants that self-seed so vigorously they border on weeds.

Okay, you’ve obtained a straw bale and you’re ready to cover the soil around your plants. How deep should the straw be piled? How close to the plants should you go? Break apart the straw with your hands (or any mulch you’re using, you don’t want thick chunks that water can’t penetrate) and place a two to three inch layer on the ground. I try to keep the straw or other mulch from touching the plants in the hopes that a little separation will make it harder for any insect pests to crawl from the straw to my plants, but this is mostly wishful thinking on my part. Once placed in the garden or flower bed, thoroughly wet the straw – if you don’t, wind can pile it against the tallest stems in the garden.

Each time you water, the mulch will help conserve the water you’ve provided your plants. Deep watering every two to three days is better for your plants than shallow, daily watering. Watering less frequently (on the 2-3 day schedule) for longer time allows the moisture to penetrate deeper in the soil and the plants’ roots will follow this water, producing sturdier plants that can access more nutrients and that are more drought tolerant.

The other benefit to mulch is that it makes growing conditions harder for weeds. Many weed seeds need sunlight to germinate. If the soil is covered with mulch and no sun is hitting those hidden weed seeds, no weeds will sprout. If tenacious weeds do manage to sprout and wend their way through the mulch, they are easier to pull by hand as the growth through the mulch leaves the stems elongated and sometimes their roots are above, or almost above, ground.

Remember how I said decomposition is always happening? Mulch starts decomposing as soon as you place it in your garden. Through the summer, as you notice that your 3 inches of mulch has now become one, refresh your mulch layer. I often use carrot and radish tops to add to my mulch as I’m harvesting along with unwanted dill plants and weeds that have snuck into my tidy rows.

Using mulch means happy plants, less watering, and fewer weeds. Mulch – it does the garden good!