Proper construction of a gravel bed depends largely on digging the area to the correct depth. The perfect depth, in turn, depends on local site conditions and the intended plant species. This guide will familiarize you with all the premises that result in the ideal excavation depth for your gravel bed.
How deep a gravel bed should be dug depends on the nature of the soil
Soil quality determines the excavation depth - you should pay attention to this
Contrary to popular belief, creative bed design with gravel is not limited to sunny, dry locations. The easy-care bed variant with a gravel ground cover is in fact suitable for almost all soil qualities. The rule of thumb for the excavation depth is: the wetter the soil, the deeper you dig. The most important data at a glance:
- Sandy-dry, well-drained soil: 20 to 25 cm deep
- Fresh, moist garden soil: 30 to 35 cm deep
- Moist soil with risk of waterlogging: 40 to 45 cm deep
If you have decided on a border of curb stones, dig out the ground 30 to 35 cm deep along the marked course. At this depth, there is enough space for a stabilizing strip foundation made of gravel and concrete.
Include root ball height in calculation
The recommended excavation depths apply to a gravel bed in which perennials and flowers stand out. However, if your planting plan includes shrubs with expansive root balls, you should dig deeper. In order for a garden bonsai such as Korean fir (Abies koreana) or mountain pine (Pinus mugo) to take root in the Japanese gravel bed, measure the height of the root ball and adjust the depth of the case accordingly.
Slight gradient prevents waterlogging
If the gravel bed is in a damp region of the garden, adding gravel to the topsoil is not enough. If you also lift the floor with a minimal incline, excess water can drain off easily. With the help of the gravel layer, you can optically compensate for the gradient.
tips
With boulders you set impressive accents in the gravel bed and create a third dimension in the appearance. In order to put the stone eye-catcher perfectly in the limelight, dig out the soil at the location so deep that you can sink the monolith by a third.