BEFORE STARTING … Research the best growing conditions for your plant. Plants that are well suited to their site will establish quickly, have a healthy root system and be better equipped to resist pests and diseases and thrive and grow.
What?
Root washing is the research-based method for identifying and correcting root bound trees, shrubs and woody perennials before transplanting.
It is the process of removing the planting medium from the roots of a tree or shrub before transplanting or when re-planting a tree or shrub that had been poorly planted or is not thriving.
Root washing is appropriate for plants with well-defined and not fibrous root systems.
Why?
The roots of plants grown in containers for several years frequently have a crowded, distorted rooting habit and often grow around the container in a spiral. Unless roots are untangled, this spiral growth pattern will continue, resulting in poor growth, stem instability, and sometimes plant death.
Coiled and crowded roots.
Root girdling: A spiral root thickens over time and girdles the bole. This can lead to the plant’s death.
These roots have taken on the shape of the container.
How?
To wash the roots:
- Root washing can be done with the root ball either on the ground (which will kill your back), or in a wheelbarrow (which will kill your back more slowly). Just don’t do it in the garden bed and turn the soil into mud.
- Use a hose with a nozzle set on “Jet”.
- Wash ALL of the planting medium off but minimize blasting the roots too much. Depending on root entanglement, removal may take a few minutes or an hour or more.
- Gently untangle the roots using a root hook, if available.
Note: To see root washing in action, view the VIRL Gardening Series on root washing under Resources #2.
When?
Root wash when the plant is dormant in the fall, before the soil freezes, or early spring.
Plant
Refer to the second part of this series: What is the Best Method to Transplant Trees, Shrubs & Perennials? Part 1: Transplanting.
Resources
- Prevent girdling roots from choking out your trees. 2021. https://novi.org/News/Prevent-girdling-roots-from-choking-out-your-trees.aspx
- Gurrad, D. 2024. Root Prep for Successful Transplanting. VIRL/Virtual Gardening Series. https://my.nicheacademy.com/virl/pathway/30786/course/26567/lesson/191031
- Chalker-Scott, L. 2021. Why root washing is important – an illustrated cautionary tale. The Garden Professors. https://gardenprofessors.com/why-root-washing-is-important-an-illustrated-cautionary-tale/
Vancouver Island Master Gardeners
Vancouver Island Master Gardeners are local volunteers who educate the gardening public with current, science-based and environmentally responsible horticultural information. As a chapter of the Master Gardeners Association of BC (MGABC), our program and priorities shape healthy communities and a healthy planet.