Old Fashioned Q and A

Bark mulch

by Mark and Ben Cullen

With the recent long May weekend, a time when gardening activity is at a fever pitch, we are here to help. Based on our experience, here are some of the most frequently asked gardening questions this time of year and our answers.

What can I plant in the shade? There are countless flowering plants and shrubs that thrive in shady locations. Hostas, yews and ferns are only three of our favourites. Without the space here to list them all, the best advice we can give you is to look at the labels and tags that come with most plants you buy. A lot of time and energy goes into this information. Often symbols are used to conserve space on the tag. Look for a half sun or a blacked in circle indicating a shade tolerant plant. An open image of sun indicates that it thrives in full sunshine.

How can I grow grass under a tree? You cannot. Well, you can if you commit yourself to an annual regimen of spreading triple mix over the root zone of the tree about four to five centimetres thick. Broadcast grass seed over the area either by hand or use a handheld seed spreader. Rake smooth and step on the mixture to bring the seed and soil in firm contact. Use a seed blend that is at least 60% red fescue. Water until established. Next spring, repeat.

Alternatively, plant a shade tolerant ground cover. Periwinkle (Vinca minor) and Lily-of-the-valley (Convallaria majalis) have been popular in the past, but they are discouraged as they are invasive. Instead, try Wild Geranium (Geranium maculatum) or Starry Solomon’s Seal (Maianthemum stellatum) or Sweet Woodruff (Galium).

How much soil do I need to plant? We do not recommend black earth (turns to dust when dry) or topsoil (lacks natural nutrients) for planting. Instead use triple mix, equal parts peat, compost, and clean topsoil. For most trees, shrubs and evergreens use three to four times the volume of new soil to the volume of soil in the pot. A two-gallon pot will require at least 8 to 10 gallons of new soil. Dig the hole two to three times wider than deep as most plants root laterally vs. vertically. Push new soil around the roots of new plants using the heal of your foot. Water deeply within an hour or so of planting. Continue to water as the soil dries to about five centimetres deep. Plant high, allowing the water to drain away from the new plant. It will settle.

What is the best weed control? Weeds outcompete most any plant that you put in your garden. Left uncontrolled they choke desirable plants out of existence and rob them of moisture and nutrients. Our #1 choice for suppressing weeds (note that we did not say eliminating them) is natural bark mulch spread about 5 to 7 centimetres thick. We prefer natural cedar or pine bark mulch to the coloured options as they are just died wood chips. As bark breaks down over the years it adds beneficial nutrients to the soil. Wood chips rob soil of nitrogen and can make some plants hungry.

We do not recommend weed barrier cloth, or landscape fabric. The idea that polyester spun material supresses weeds is a myth. When weed roots become entangled in it, the only thing it supresses is our desire to garden. It is useful under patio slabs and interlocking brick but even there it is not a panacea to a weed free existence.

The best advice we can give you for weed control is a sharp weeding hoe, used early in the season before young weeds get a strong root down. Once you find your rhythm at this job you might learn to really like it, as we do.

Mark Cullen is an expert gardener, author, broadcaster, tree advocate and Member of the Order of Canada. His son Ben is a fourth-generation urban gardener and graduate of University of Guelph and Dalhousie University in Halifax. Follow them at markcullen.com, @markcullengardening, and on Facebook.