Should 30-year old soil be renewed to plant a new hedge?

Garden Experts

A cedar hedge has thrived over the last 30 years on the edge of a terrace raised with soil (approx. 50 cm high). It wasn't cut in the last four years. In the end, it died. Now, the question is whether a new hedge, such as another cedar, could be planted there, or is the soil depleted after 30 years? As I said, it's not level earth, rather slightly loose soil on a slope.

The GARDENA gardening expert answers

Usually, you can replant hedges. If you leave the stumps of the cedars you have cut down in the ground, the soil will hold together better on the slope while the new hedge takes root in its first few years. However, to be able to plant anything in the existing tangle of roots, some effort is required. It is easier if you use younger plants with smaller root bales. Then again, it can take a little longer for the new hedge to reach its target height. In principle, you can plant cedars on the condition that the reason the old hedge died was not an infection that could spread to the new cedars.

You can also use other shrubs suitable for hedges. Columnar juniper trees or yew trees, for example, almost never need cutting, and column apples only need cutting rarely. Ornamental shrubs such as Philadelphus 'Erectus' or the oval-shaped garden hibiscus plant are generally suitable for hedges and do not require much cutting. It is a question of how effective the hedge needs to be as a privacy screen in its chosen position — with the hedge density and the hedge height being important factors. In order to be completely out of sight behind a hedge, the hedge must be at least 150 centimetres high.

Regardless, treating the soil will ensure better growth for the next generation of your hedges, even as early as the planting stage. The soil:compost ratio should be 3:1 and the ground should be treated annually, initially with one litre of compost per square metre, then two to three litres in subsequent years. There is no need to overfeed the soil because the slower the hedge grows, the denser it will become. Also, as the old cedar roots gradually rot, they will become an initial dose of fertiliser.