Sow directly in the garden in spring when night temps stay above 10C. Plant 1/2″ deep in well-drained soil, spacing seeds 4″ apart. When seedlings reach 3″ tall, thin remaining plants to 1′ apart, so these big plants have room to grow. Sunflowers grow best when watered regularly throughout the season. Cut flowers often to prolong bloom. Easy and fun to grow with children.