Hi Christian,
I would recommend a potting mix that is slightly acidic as root crops prefer such an environment (pH 6 – 6.8). However, if you are growing microgreens, coco coir is another great soilless media option. Additionally, microgreens really benefit from the nitrogen in a sprinkling of earthworm castings, so you might think about having some of those on hand as well. Check out the links to these products and good luck!
Roots Organics Potting Soil: pH 6 – 6.5
Fox Farm Natural & Organic Ocean Forest: pH 6.3 – 6.8
Roots Organics Coco Palms: pH 5.2 – 6.3
Roots Organics Coco Fiber Bale: pH 5.2 – 6.3
Wiggle Worm Earth Worm Castings: pH neutral
Hope this helps!