In the lush landscapes of the Pacific Northwest, particularly in areas like Vancouver, planting under trees can be a unique challenge. The dense canopy and extensive root systems of local trees, such as Douglas Firs and Western Red Cedars, create a special microenvironment.
As a tree grows and its branches and roots expand, the area around it can become a barren. Tree roots quickly soak up lots of available water and can blocking the sun, so selecting shade-tolerant (aka understory) plants is a must.
Fortunately, it is possible and relatively easy to create a lovely, dense fill of small plants at the base of trees. This article offers 10 practical tips to transform the space under your trees into a thriving forest garden, thereby enhancing the natural beauty of our region.
Protecting Tree Roots
- Root Protection: Use small trowels instead of shovels when planting to protect tree roots. Doing this protects delicate roots and their mycorrhizal network because approximately 80% of a tree’s roots are found within the first 18 inches of soil.
Plant Multiples: Use multiples of the same plant for a cohesive look. Additionally, consider native species like Salal and Sword Fern for their resilience and low maintenance. Species native to the area are also well adapted to shade.
Watering and Plant Selection
- Regular Watering: Newly planted seedlings under the canopy require consistent watering, especially during dry summers. Also use a soaker hose and rain barrel system to conserve water.
- Selecting Seedlings: Trees need large root balls but for plants, you can opt for smaller seedlings, known as “liners”. This approach ensures minimal disturbance to the tree and better establishment of plants.
- Foliage over Flowers: Choose plants with attractive foliage. In contrast, flowering plants often struggle under the dense canopy, whereas ferns and hostas thrive. If you are looking for seasonal colour, many flowering native species are well adapted to shade.
Planting Strategy and Drought Preparation
- Diverse Planting: Instead of a ring, fill in spaces around the tree. This mimics the natural forest floor and supports biodiversity.
- Drought Planning: Select drought-resistant plants like Oregon Grape, as they adapt well to the dry shade under trees.
- Soil Improvement: Mulch properly and incorporate organic matter into the soil. To achieve this, use products like BioChar and improve water and nutrient retention in soil.
Photo Credit: Kolforn (Wikimedia), CC BY-SA 4.0, via Wikimedia Commons
Ecosystem and Wildlife Considerations
- Avoiding Invasives: Choose non-invasive or native plants to protect local ecosystems. Contrary to popular myth, non-native species are not the same as destructive invasives (which need to be avoided at all costs). Check out our tips here.
- Wildlife-Friendly Choices: Select plants that have nuts, nectar and fruit to support local birds and insects. Look for lawn alternatives and increase bird-friendly features like woody debris, shrubs and wildlife trees.
Planting under trees in the Pacific Northwest, with its unique climate and ecosystems, requires thoughtful consideration. By following these tips, you can create a beautiful and sustainable garden that complements the natural beauty of regions like Vancouver, BC.
For more detail on these tips and others, check out this great article from The Spruce.
Image Credit: Terie Rawn via Fine Gardening
