Planting in Flower Beds Choose mums that are still tightly budded. Gently tease the roots apart as you set out mums in their planting hole. Mums grow best in rich well drained soil. They prefer a position in the garden with at least a half day of sun. They also require plenty of air circulation around each plant. No fertilizer is required during the fall season. Water newly planted mums immediately after transplanting. During dry spells water as needed to …