Mice, Voles and Moles, oh my!

  • Difficulty Rating: Beginner
Mice, Voles and Moles, oh my!

Understanding these small creatures is key to stopping them from damaging your garden.

Of the three, voles are the worst marauders consuming nearly any vegetation in their path. That means tree bark, roots, root vegetables, and most bulbs aren’t safe from their voracious appetites. Moles are the most noticeable because they create large tunnels in your lawn as they search for grubs beneath the soil, but they don’t eat plants. Get rid of the grubs, and moles will move on, but that’s a different article for another time.

If it is available, voles (sometimes incorrectly identified as field mice) and true field mice love loose soil and bedding materials like grass clippings, leaf piles, hay and mulch.

In recent years, homeowners have gotten the message that mulch does several beneficial things for our gardens. It suppresses weeds, regulates soil temperature and moisture and can improve soil fertility. However, there is a dark side to mulch. Many of us are guilty of over mulching and doing it incorrectly especially when mulching around trees.

Consider how trees grow in their native habitat, the forest. They aren’t surrounded by a pile of shredded tree bark. Instead, mature trees have large roots which flare out beneath them, creating stability for their majestic stature. Neither mulch nor soil should cover this flare or a young tree’s more evident root crown. Further, mulch shouldn’t lie against the bark of trees or the stems of shrubs and perennials. For example, the large crapemyrtles shown in the photograph above are mulched only with their own spent leaves.

As I drive through town, especially in more affluent neighborhoods where lawn companies are out in force, I see their employees adding a deep and wide swath of mulch over beds and borders and around trees. It may create a neat appearance much like wall-to-wall carpeting indoors, but it isn’t good for the plants.

Young Arizona cypress properly mulched

Homeowners often imitate what they see in their neighborhood so the problem is intensified. Layering mulch too thickly and placing it too close to trees encourages rotting tree bark and also lures mice and voles who chew on and dig around plants. If you see damage a bit further up on the tree it is probably done by rabbits. Voles love tulip bulbs, so if you plant tulips and in the spring, they only come up sporadically, you can bet they were eaten by voles.

Mulching young trees especially is a good idea, but follow these guidelines:

  • Mulch around the drip line of the tree. You can find the drip line by looking at the end of branches and drawing an imaginary line down to the ground.
  • Don’t apply too much mulch. Two to four inches is plenty if you have good drainage. For clay soils or areas which don’t drain well, less is better.
  • If you use slow decaying mulch like cypress, you don’t need to apply it every year. Instead, if you want it to look fresher, fluff it with a rake or garden fork.
  • Consider mulching with materials locally available in your area like your own shredded leaves? They decay faster and add nutrients and beneficial fungi to the soil. For more acidic mulch, if you live in the south, try pecan hulls or shredded pine bark.
  • Do use mulch which decays. This rules out rubber chips which should only be placed on children’s playgrounds and rocks which compact soil and plant roots.