How to grow a tall sunflower

Height is part genetics, part care. Get these basics right and you'll give your sunflower every chance to tower.

The tall-sunflower checklist

• Start with a giant variety. Height is mostly in the genes — look for American Giant, Mammoth / Russian Giant, Titan, Sunzilla or Skyscraper. A "Teddy Bear" will never be tall, however well you grow it. (See sunflower types.)
• Full sun, all day. Sunflowers want 6–8+ hours of direct sun. The sunniest, most sheltered spot you have will always beat a shady one.
• Deep, rich soil. Dig in plenty of compost or well-rotted manure and loosen the soil deeply — tall plants need a big, deep root system to anchor and feed them.
• Sow direct, or in deep pots. Sunflowers dislike root disturbance. Sow where they'll grow, or start them in tall pots and plant out carefully while young.
• Don't crowd them. Give giants room — roughly 45–60 cm apart — so they aren't competing for light, water and nutrients.
• Water deeply and often. Keep the soil consistently moist, especially in the weeks before the flower bud forms. Deep, less-frequent soakings encourage deep roots.
• Feed for growth, then for bloom. A nitrogen-rich feed early builds tall, leafy stems; switch to a more balanced or potassium-rich feed as the bud appears.
• Support and shelter. Stake tall stems and shield them from strong wind — a snapped stalk ends the record attempt. A wall or fence at their back helps.
• Guard the seedlings. Slugs, snails and birds love young sunflowers. Protect them until they're well established.
• One stem, one head. For the tallest single bloom, grow one strong central stem and don't pinch it out.

Common problems