By: Bill Reichenbach, Certified Arborist WI-0188A
Tired of mowing under or around your trees? Want to plant in the mulch bed under your tree? Perhaps you would like to create a ‘woodland garden’ in your part of the urban forest. Planting under trees is a wonderful way to create a lush, sustainable and beautiful home landscape.
It is good for your trees as well. As arborists, we are always encouraging our clients to eliminate turf grass from around your trees. Turf grasses compete with the tree’s shallow feeder root system for nutrients and moisture. Turf grasses have been shown to have allelopathic (suppression of growth by release of a toxin) effects on tree roots as well!
There are abundant choices of shade-tolerant plants for planting under trees. Many groundcovers and herbaceous perennials, as well as a great selection of small- scale trees and shrubs, thrive in the shade of canopy trees. Many of our native woodland plants are perfect additions to the landscape under your trees.
When planting trees and shrubs in the understory of existing trees, do not plant the biggest plants you can find. Large balledand-burlapped plants demand large holes. Large holes can result in damage to the existing tree roots in the planting process. Smaller balled-andburlapped or container-grown plants are easier to handle,establish quickly, and the smaller holes needed to plant them are easier on the existing tree’s roots.
Groundcovers and herbaceous perennials typically are planted in 1-gallon or smaller pots which can be pocket planted nicely to fill in the spaces under trees. If you run into a large tree root in the planting process, move the plant over. Avoid digging through roots larger than an inch or so.
After planting, place 2-4 inches of an organic mulch around the plantings under the trees. Keep the mulch 3-4 inches away from tree trunks and do not bury the stems of shrubs or perennials. Organic shredded bark or wood chip mulches slowly help to recreate and mimic the natural forest floor that is very beneficial to tree health. The benefits of mulches are many: moisture retention, moderation of soil temperature extremes, weed control and reduction of compaction. One of the most important is the recycling of nutrients of the mulch as it biodegrades. The addition of this organic matter improves soil structure, increases the soil’s moisture and nutrient holding capacity and increases beneficial soil microorganisms.
There are many great shade tolerant plants to choose from. Ironwood, musclewood, witchhazel and pagoda dogwood are understory woody plants that can help fill the mid-layer under the high canopy. Serviceberry and redbuds are beautiful flowering trees that will grow well in partially shaded areas. A great many herbaceous plants growing a few inches tall up to 3 feet or more offer a myriad of selections. Numerous ferns, hostas, and sweet woodruff are sure bets. Wildflowers like wild geranium, bloodroot, wild ginger and bellwort are naturals under trees.
As in any gardening endeavor, planning is crucial. Proper selection and placement of the right plant in the right place is important to success. Get professional horticultural advice if you are not a shade gardening guru yourself.
For the tree’s sake, let’s get rid of some turf and plant a natural garden under your trees!
© Copyright 2009 – Wachtel Tree Science & Service, Inc.