Dahlias are best grown in the

Dahlias are best grown in the ground. If you try containers, use a pot size no smaller than 12 x 12 inches per tuber. For pots, dwarf dahlias work best not standard sizes. Use 2 parts garden soil, 1 part potting soil that has not been treated in any way. Water and keep your soil slightly damp. After plants are 12 inches high, potted dahlias will require extra watering and fertilizing to promote proper blooming.