Sandarium
Around 75% of all wild bees build their nests in the ground.
A sandarium is a dry, sunlit area of sand with little vegetation that is created as a nesting area for ground-nesting wild bees and insects. By specifically integrating open ground into your garden, you can help to promote wild bees.
Step 1
Get material
The right sand is crucial for building a sandarium. You will need:
- Spade or shovel
- Wheelbarrow or bucket (if required)
- Loam, loess or sand (approx. 0.5 m³/m²): Unwashed sand from a local quarry, with a grain size of 0-2 mm, is ideally suited. River sand or playground sand are unsuitable as they are too unstable, causing the nesting tunnels to collapse and spill. The soil or sand should come from the region, as the local insect fauna is adapted to the naturally occurring soil type.
- Materials such as dead wood, stones, cut branches for enclosure
- Plants (if required)
Step 2
Select a location
The selection of a suitable location is also important for the successful establishment of ground-nesting insects. To do this, you should know the requirements of the species you want to encourage. Most wild bee species prefer a sunny, warm and dry location to build their nests, which is why a south-facing slope offers ideal conditions for these species. The south side of a building or wall, for example, is also suitable as it radiates additional heat and offers some protection from rain and wind. The area should be several square meters in size.
During the planning stage, you should ensure that the sandarium can survive for many years in the chosen location. The colonization of a sandarium can take several years, but the patience and longevity of the sandarium will be rewarded by its loyalty to the location, as the offspring often return to the place where they were born.
Step 3
Fill up the sand
Remove the vegetation from the chosen location. Then dig a 60 cm deep hollow. If you are forming a mound, it is sufficient to dig 20-30 cm deep. Fill the hollow with sand and create a small mound so that the rainwater can run off and the sand dries more quickly. You can also integrate a south-facing steep face into the mound. Press the sand down lightly and compact it. This will improve the thermal conductivity.
Tip:
- To test whether the sand has the right composition and “consistency”, i.e. is not too hard but still sufficiently stable, you can stick a finger or stick into the sand. If this does not work, the sand is too hard. If the hole collapses, the sand is too loose and does not have enough fines.
Step 4
Create structures
To create additional structures and make the sandarium more appealing, you can use elements such as deadwood, a pile of stones or individual boulders. Cut branches from prickly shrubs can deter pets from entering the area.
Step 5
Planting
Optionally, you can lightly plant the sandarium with species such as wild thyme (Thymus serpyllum) or the Carthusian pink (Dianthus carthusianorum).
Maintenance
To avoid compacting the soil, you should not walk on the sandarium. The soil should remain as undisturbed as possible and should not be loosened or hoed. You could carefully weed by hand outside the breeding season to avoid shading the area. Plants that have been deliberately planted in the sandarium should be cut back to limit seeding and spreading. Remove foliage that covers the soil in the fall. During nesting activities in spring and summer, water the area sparingly or preferably not at all.
Tip:
- In public areas, especially near paths, a sign can help to ensure that the sandarium is not used as a playground.