You can store seeds until spring sowing in the
refrigerator and in another substrate(wet sawdust, sand, peat), but Sphagnum moss is the best option.
You can acidify the soil, for example, with Sphagnum moss or sheet compost.
In order to create a small rock garden about 2.5 x 1.5 m in size, you need about 2 tons of large, heavy stones.