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Helianthus (hee-lee-AN-thus)

Common Name:  Perennial sunflower

Light:  - Full sun to part sun

Soil:  Average to loamy, well-drained

Moisture:  Average to somewhat dry

Blooms:  Late summer to fall

Zones:  (4) 5 - 8 (9)


Helianthus 'Capenoch Star'

Helianthus 'Multiflorus'

Helianthus Description and Cultural Information

Many are surprised to find that their really are perennial sunflowers. They all tend to have yellow flowers in late summer and a spreading habit, some more rampant than others, but their long bloom season and bright, cheerful flowers more than make up for that.

Helianthus angustifolius, swamp sunflower. 4 - 8'. This is a very tall plant with deep-green, lance-shaped leaves covered with a profusion of bright yellow flowers in September to frost. As its name suggests, this particular species will tolerate wet soil. It is a very aggressive spreading plant. Zones 6 - 9.

Helianthus giganteus, giant sunflower. 7 - 12'. The giant sunflower is even taller than the swamp sunflower, but it is not as aggressive. Plants need staking and some protection from strong winds. 'Sheila's Sunshine' is a light, primrose-yellow. Zones 5 - 9.

Helianthus x multiflorus, multi-flowered, double sunflower. 4 - 6'. This hybrid has a profusion of large, double yellow flowers from late summer to fall. Plants spread slowly to form dense clumps. 'Capenoch Star' is a natural single flowering mutation of this plant that is actually very attractive. Zones 4 - 8.

Helianthus 'Lemon Queen' is a very tall hybrid with thinner leaf blades and small, lemon yellow flowers that bloom profusely from summer to frost. This variety also spreads from dense runners and self-seeds fairly easily. Zones 4 - 8.

How to Grow:  Helianthus generally prefers to be grown in average to rich, well-drained soil in full sun. Plants will tolerate some shade but may not be as sturdy. Allow plenty of room as they all spread to form a very impressive clumps. Divide every 3 or 4 years if blooms diminish or to maintain their large stature and control their spread. Plants benefit from regular watering and light fertilizing for best blooms, but overfertilizing will result in rampant green growth and they should never be wet, especially in the winter, with the exception of the swamp sunflower.

Landscape uses:  The dark green leaves of perennial sunflowers make excellent backdrops to summer blooming plants such as hardy geranium, baby's breath, Liatris, Echinacea, garden phlox, and daylilies. The bright yellow flowers make a nice companion to purple ironweed (Vernonia), Buddleia, and bluebeard (Caryopteris). They also go well with ornamental grasses.

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