Living Walls™ need soil that holds sufficient moisture while allowing excess water to drain away. Roots need both moisture and oxygen. When soil remains waterlogged, water fills the air spaces and reduces the oxygen available to the roots.
If water regularly pools along the proposed hedge line, or the soil stays saturated for long periods after rain, address the cause before installing your hedge. A planting trench alone will not correct a wider drainage problem.
Inspect the proposed hedge area, particularly after sustained rain. Standing water, persistently soft ground, heavy compacted soil or water flowing into the area from higher ground can all indicate a drainage problem.
Conditions may vary along the hedge line, particularly on sloping or recently developed sites.
Dig a hole approximately 300 mm deep at several points along the proposed hedge line. Fill each hole with water and observe how it drains. If the water drains away, refill the hole to saturate the surrounding soil and monitor it again.
The test is a practical indicator rather than an exact measurement. If water remains in the holes for many hours or is still present the following day, seek advice before installing.
Do not place gravel, scoria, compost or garden mix in the bottom of the planting trench.
A layer of coarse material does not provide somewhere for the water to escape. Instead, water can remain in the soil above the layer and around the rootballs.
Living Walls™ installed in the ground should be backfilled with the excavated site soil, as explained in our In-ground Installation Guide.
Water may be collecting because of compacted soil, the natural slope of the site, runoff from hard surfaces or a high water table.
Minor surface-water problems may be improved by shaping the surrounding ground so water moves around, rather than towards, the hedge line. Avoid working or walking on wet soil, as this can compact it further.
Where appropriate, the entire hedge line may be formed as a raised bed or low mound. The sides of the rootballs must still be covered and supported by soil.
Persistent waterlogging may require a properly designed subsoil drain with adequate fall and a suitable outlet. This should be assessed by a landscape or drainage professional.
Drainage problems are easier to correct before the hedge is installed.
If you are uncertain whether the site is suitable, ask your landscape contractor or drainage professional to assess it before ordering or beginning excavation.
Planning your installation? See our In-ground Instant Hedge Installation Guide and Living Walls™ Specifications
