Skyscraper Sunflower Seeds

Sow Skyscraper Sunflower seed directly outdoor once the last frost has passed and daytime temperatures settle above 60°F. Plant each seed an inch deep, 18 to 24 inches apart, in rows about 3 feet apart. Germination takes 7 to 10 days in warm soil, and you can speed it up, soaking the seeds overnight. We don’t recommend starting inside, because the taproot grows long fast and resents disturbance. If your season is short, the workaround is to start them in deep biodegradable pots three weeks ahead and plant the whole pot in the ground without disturbing the roots.

Skyscraper Sunflowers need full sun — at least 6 to 8 hours of direct light per day, and more is better. They can grow in almost any soil, but give them deep, well-drained, compost-rich loam and you will get the full 12-foot stalks and the largest heads. Water deeply once a week during the first month, then ease off as the taproot reaches deep enough to pull moisture from 4 feet down. Don’t water overhead once buds form, because wet petals invite mildew in dense plantings. Apply balanced fertilizer at planting and during bud formation.

Stake Skyscraper Sunflowers plants once they pass 5 feet, especially in windy areas. Use an 8-foot bamboo cane or a piece of steel rebar driven a foot into the ground behind the plant, and tie the stem with soft jute twine every 2 to 3 feet as it climbs. Cut blooms for vases in the morning once the petals fully open, leave 2 feet of stem, and they hold up to 7-10 days indoors. For seed harvest, wait until the back of the head turns brown and the petals drop, then cut the head and hang it face-down indoors for 2 weeks.