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Annual Biennial

Helianthus annuus 'Florenza'

sunflower 'Florenza'

A branching annual to a height of around 110cm with green leaves. Rusty maroon-red flowers with yellow tips and dark chocolate-brown centres appear throughout the summer. A great choice for borders and for cutting

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Ultimate height

1–1.5 metres

Time to ultimate height

1 year

Ultimate spread

0.1–0.5 metres

Chalk

Clay

Loam

Moisture

Moist but well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

East–facing or South–facing or West–facing

Exposure

Sheltered

Hardiness
Hardiness ratings
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H1a: under glass all year (>15C)
H1b: can be grown outside in the summer (10 - 15)
H1c: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20)

Botanical details

Family: Asteraceae
Native to GB / Ireland: No
Foliage: Deciduous
Habit: Bushy, Clump forming
Genus: Helianthus can be tall, erect annuals, tuberous or rhizomatous perennials, with coarse simple leaves and large daisy-like flower-heads
Name status: Unresolved

How to grow

Cultivation

Grow in moderately fertile, neutral to alkaline, humus-rich, moist but well-drained soil in full sun. This plant was included in the RHS Helianthus (sunflower) trial 2024 https://www.rhs.org.uk/plants/trials-awards/plant-trial-results/fleuroselect-sunflowers

Propagation

Propagate by seed (sown indoors) between April and May and keep in a sunny location, planting out in late spring or early summer when the risk of frost has passed. Also propagate by seed (sown outdoors) when the risk of frost has passed

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Patio and container plants
Wildlife gardens
Flower borders and beds

Pruning

Cut back after flowering or leave flower heads for birds to eat seed

Pests

May be susceptible to slugs and snails

Diseases

May be susceptible to powdery mildews and sclerotinia diseases

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.

Helianthus annuus 'Florenza'

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