Regenerative Practice: Planting and Seeding for Soil Decompaction
The in-depth study of the plants in the garden and its underground life forms has enabled us to propose an intervention that responds directly to the site, following the method of the Garden of the XXI century.
Part of the garden was compacted by a truck route in 2005 during the construction of the neighboring daycare center. The soil there is very stony and contains building materials just below a thin layer of about 10 cm of topsoil. Soil life is poor, roots have difficulty penetrating deep into the soil and plants have difficulty growing. The most important plants to be found on the site are Medicago sativa, Sanguisorba minor and Bromus erectus. These plants tend to grow in dry, nutrient-poor soils, what corresponds well to the situation we find on site. The intervention aims to preserve the deep-rooted species that are already growing on site and add new plants with similar characteristics. The hypothesis is that these will decompact the soil, slowly penetrating the hard layers of stones and earth, while creating more attractive conditions for the establishment of new soil life over time.
After marking the intervention area, we identified existing plants with strong and deep roots - Medicago sativa and Sanguisorba minor. Around these plants, we removed the grass layer by hand, taking care to leave all the soil in the area, while only removing potential competition for our new plants. We used 90 seedlings of Salvia pratensis, Centaurea scabiosa, Chicoricum intibus, Malva moscheta alba and Onobrychis viciifolia that we have bought in a local garden centre.
We checked that the plants chosen were suitable for the site. We chose plants with similar ecological values to those present on the site.
Between these agents of change we seeded a mix of seeds including Medicago sativa, Papaver rhoeas, Sinapis arvensis, Sinapis alba, Silene pratensis, Daucus carota, Brassica rapa and Oenothera biennis. After distributing the seeds on the bare soil, we pressed them with some light weight into the ground.
With small stones that we have found while taking the grasses out, we constructed a small barrier around the new garden. In the beginning we supported growth by watering the plants a little. After a few weeks, we can already see the seedlings growing and the seeds sprouting, but we will see how they develop in the long term.
The two drawings below show the initial and hypothetical future state of the soil before and after the planting of soil decompaction plants with deep and strong roots.
The Cichorium inthybus plants quickly established themselves and produced a large number of flowers in Septembre, about 4 months after being planted. It would be interesting to uproot one of them and observe how the roots have developped.
Despite sowing a very large quantity of seed, the plants failed to establish themselves. There was too much competition from other plants already present in the soil and from the surrounding area. Of the five species of seedlings planted, two established well (Onobrychis viciifolia and Cichorium intybus) and three died (Salvia pratensis, malva moschata, Centaurea scabiosa). In September 2024, Onobrychis viciifolia produced large rosettes but still few flowers. Cichorium intybus grew into tall shoots and many flowers. Salvia pratensis rotted and was eaten by slugs. May and June 2024 were particularly rainy and probably too wet for Salvia pratensis plants, which prefer dry conditions. In May 2024, some Malva moschata seedlings had already died, perhaps because they did not had enough water. The centaurea scabiosa plants were vigorous in May 2024. By September, there was no trace of either Malva moschata or Centaurea scabiosa. An assessment should be carried out again next spring.
Some insects have been found at the project site. They are present thanks to the new flowers planted (Cyaniris semiargus and Apis) or thanks to the late mowing (Argiope bruennichi). This shows that insects settle in very easily if the right conditions are created.
To maintain this garden, it needs to be mowed once a year, preferably at the end of the season so that insects such as the argiope can settle in.
It would be interesting to continue introducing deep-rooted plants, following the logic of the garden. One should first identify plants with strong, deep roots that are present on site and conserve them. The surrounding plants should then be removed and new plants introduced. New plants can be introduced using seedlings or seeds. It should be noted, however, that introducing plants from seed is more difficult due to strong competition from other plants already in the soil or plants from neighbouring plots.
We hope that this garden will inspire new gardeners and that it will gradually evolve, with ever new plants, into an exciting root garden with a great diversity of roots.
