Sowing & Growing

Directly sow sunflower seeds in the garden for optimal results, ensuring they receive full sun. The Helianthus annuus ‘Rouge Royale’ variety reaches a height of 5-6 feet, with recommended seed spacing of 6 inches apart in rows 24 inches apart. Plant the seeds at a depth of 1/2 inch, and the mature plants will spread 20-30 inches. These sunflowers, displaying a deep violet-purple to almost black color, bloom from mid to late summer for several weeks, with a maturity period of 90 days.

Suitable for zones 3-9, germination occurs in 7-12 days. The flower form consists of single blooms, each measuring 4-5 inches across, adorned with bright golden stamens. These annual sunflowers thrive in well-drained garden soil and have a slow growth rate initially, but they become fast-growing once established in their location. Pruning can be done by cutting back hard after flowering above the 2nd or 3rd set of buds, either in early spring or after flowering.

The foliage of Rouge Royale sunflowers is typical, featuring green leaves. To sow directly, plant the seeds 15mm deep in finely prepared soil, raked to a fine tilth. Place two seeds together every 45cm, and seedlings will emerge in 14-21 days. Thin out the weaker of the two plants when large enough to handle, and replant elsewhere if needed. Water well until established. Alternatively, starting seeds indoors is an option. Sow into individual pots, 15mm deep, and place them in a cold frame or greenhouse. Keep the soil moist, acclimatize the seedlings, and plant them outdoors after the danger of frost has passed.