Groundcover Plants for Growing Under Trees

(Question)

I have a maple tree and an Alberta Spruce tree in my garden. Unfortunately nothing seems to grow beneath the trees. The main concern is under the tall Alberta spruce where there are no plants. Can you suggest any perennial plants that may provide some ground over. Many thanks

 

(Answer)

Growing under trees, with competition for water, nutrients and light can create a lethal environment for many plant types. Any plant that sends a tap root down into the soil is likely to struggle, or may not even get past the thick matt of existing roots created by the trees.

Try planting species that spread by producing stolons or rhizomes. These plants run along the surface of the ground, with roots just under the surface- which pick up moisture and nutrients deposited by decomposing mulch on the soil surface.

Rhizomes are modified plant stems, which send out roots at intervals to secure the plant to the soil. Stolons, also called ‘runners,’ are a means of plant propagation.  The mother plant sends out runners, which anchor and bud- producing a new plant. The two plant types a fairly similar, although rhizomes can also travel vertically into the soil if conditions allow it.

Adding a shallow layer (about an inch thick) of organic compost over the area that you would like to cover with plants will ensure your new plants will have a supply of nutrients to reach out for. The compost will also trap valuable moisture. Check this compost layer each spring and top up as necessary.

Here are a few perennial ground covers which can tolerate lower light conditions. Depending on your soil type, you may like to research the following possible plant choices:

Canadian Snakeroot aka Wild Ginger Asarum canadense

Carpet Bugle Ajuga reptans

Bunchberry (Canadas National Flower) Cornus canadensis 

Foamflower, Tiarella cordifolia

Cranesbill Geranium, Geranium maculatum

Hosta species. There are literally hundreds of different Hosta cultivars, so think about how tall you would like them to grow and what colours would look best in your garden. In dark under storey areas the bright green or gold varieties can stand out and add interest. Search ‘gold hostas’ and you will have a huge selection to chose from. For visual continuity and continuous cover,  you could also try low growing varieties under your trees and taller varieties nearby.

Another plant that lightens up a bed is  Japanese Forest Grass, Hakone macra ‘Aureola’