30 seeds 1. Stratification: Mix the seeds with moist sand or vermiculite in a plastic bag. Place the bag in the refrigerator for 2-3 months. Then move the bag to a warm place (about 20°C) for germination. 2. Sowing: Use seeding soil and pots or a seed box. Press the soil lightly and sow the seeds sparsely. Cover the seeds thinly with soil. Keep the soil moist and cover with plastic to retain moisture. 3. Germination and care: Groningen can take time, so be patient. When the plants have germinated and have a few pairs of leaves, they can be transplanted into larger pots. Plant the plants out in the garden after the risk of frost has passed.
