Sowing & Growing

Sow these seeds in either spring or autumn, avoiding extreme temperatures. The optimal range is approximately 15 to 20°C. For best results, sow early between November and March in gentle heat to allow the plant to establish fully before the following winter. Alternatively, a June to July sowing can be done if placed away from direct sunlight. Germination typically occurs within 14 to 30 days, with the entire process from sowing to germination taking 4 to 8 weeks, and from germination to transplanting lasting 4 to 6 weeks.

Prepare cells or pots with a well-draining seed compost. Moisten thoroughly by placing the containers in water, then draining. Sow the seeds on the compost surface, ensuring they receive light for germination. Lightly cover them with sieved soil or a fine layer of vermiculite. Keep the compost consistently moist, avoiding excessive wetness. Utilize a propagator or seal the containers in a polythene bag until germination, which typically takes 14 to 30 days at 15 to 20°C. If no germination occurs, expose the container to cold temperatures (around -4 to 4°C) for 2 to 4 weeks. Return to warmth to trigger germination. Remove the polythene bag once the first seedlings emerge. When they are large enough to handle, transplant them into 7cm pots for further growth, holding the seedlings by the leaves, not the stems.

Plant them outdoors in late spring or early summer, after the last expected frosts, spacing them 40 cm (16in) apart in well-drained soil with full sun exposure. For successful cultivation, Saponaria prefers full sun and thrives in well-drained soil for winter survival. Avoid fertilizing during the growing season; instead, work bone meal into the surrounding soil in early spring for the nutrients they need.