TOP 10 TIPS for PLANTING UNDER TREES IN THE PACIFIC NORTHWEST
In the lush landscapes of the Pacific Northwest, particularly in areas like Vancouver, planting under trees can be a unique challenge.
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.
PROTECT THOSE ROOTS
Consider that 80% of a tree's roots are within the top 18" inches of soil. The bulk of these roots are fine roots (the small and delicate ones that absorb water and nutrients). People often dig these up without concern. While large, established trees may tolerate this destruction, young trees are at high risk.
1. Start with Soil Health
Use soil amendments to line planting holes, but do not go overboard.
A small amount of BioChar vastly improves water and nutrient retention in the soil to protect your plants from extremes.
2. Dig Carefully
Use small trowels instead of shovels when planting to protect tree roots. This protects delicate roots and their mycorrhizal network.
3. Select For Root Health
When selecting plants at the garden centre, carefully slide young plants from their pots to check roots for problems.
Root problems are indicated by discolouration, water-logging, odours, or similar issues.
GET A NATURAL LOOK
A well-planned under-tree garden should blend seamlessly with the surrounding landscape, mimicking the natural layers of a forest floor. Instead of rigid patterns or perfectly spaced plants, aim for an organic, flowing design that mirrors how plants naturally grow in the wild.
Grouping plants in clusters, using varying heights, and incorporating native species will create a cohesive, low-maintenance space that feels like an extension of the tree itself.
4. Ditch the Lines
'Liners' refer to small nursery seedlings but they do not need to be planted this way. Instead of a rings or rows, work to fill in spaces around the tree.
Source and plant in triplets vs. pairs for a natural look. This will help you that mimics that forest look and support biodiversity
5. Go for the Understory
Tree canopies, especially conifers can block the sun, so selecting shade-tolerant (aka understory) plants is a must.
If you're looking for colour, natives and nativars are well adapted to shade.
6. Foliage Over Flowers
Choose plants with attractive foliage. In contrast, flowering plants often struggle under the dense canopy, whereas ferns and hostas thrive.
Consider species like Salal and Sword Fern for their resilience and low maintenance.
Get in the 8B Zone
Planting under trees in Zone 8b, which includes areas like Vancouver, BC, requires special care due to the region's mild winters, wet springs, and dry summers. The dense canopies of trees, combined with extensive root systems, create challenges for light, water, and nutrients.
7. Water Plants In the HEat
New seedlings under the canopy still require watering, especially during dry summers.
Drought-resistant plants like creeping Oregon Grape, as they adapt well to the dry shade under trees. Use a soaker hose for best results.
8. Forget Turf
As trees grow, their expanding branches and roots create shade and compete for water, often leaving the area barren. Turf makes this bad situation worse.
Avoid the hassle—use mulch! A 2-inch layer protects against weather extremes and serves as natural fertilizer.
9. Caution with Groundcovers
It’s tempting to pick fast-growing, shade-tolerant species, but these same characteristics often mean they are invasive (I'm looking at you periwinkle).
Consider the effort needed to control the relentless spread before you go all-in.
10. Choose Natives or Nativars
Choose native plants or nativars—they're perfect for our region and support local ecosystems. For more info on native plants click here.
For more detail on these tips and others, check out this great article from The Spruce.
