Iris 'Blue Hill' (Reticulata)

RHS / Janet Cubey

Bulbs

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A bulbous perennial, to 12cm in height, with erect, green, strap-like leaves and violet-blue flowers in spring; the falls have a white speckled throat and a yellow central band

Position

Full sun

Soil Types

Chalk, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0-0.1 metre

Size

Time to Maturity: 2–5 years
Max Spread: 0-0.1 metre
Max Height: 0.1-0.5 metres

Growing Conditions

Chalk Loam Sand

Moisture: Moist but well–drained or Well–drained
pH: Alkaline or Neutral

Position

Full sun

Aspect: South–facing or East–facing or West–facing
Exposure: Exposed or 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): H7

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Iridaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Columnar upright
Potentially harmful: Harmful if eaten. Wear gloves and other protective equipment when handling. Pets: Harmful if eaten. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus: Iris may be rhizomatous or bulbous perennials, with narrow leaves and erect stems bearing flowers with 3 large spreading or pendent fall petals, alternating with 3 erect, often smaller, standard petals, in late winter, spring or early summer
Name Status: Accepted
Horticultural Group

Horticultural Classification Codes

Horticultural Classification Codes are often given to genera which have a large number of species or cultivars. They are used to categorise cultivated plants based on specific, shared characteristics such as shape, colour, size or flowering time, and can be displayed as letters or numbers

For example:
Dahlia ‘Sunset Kate (Sin) = Single flower
Rosa ‘Marigold’ (HT) = Hybrid Tea: Reticulata irises are small, bulbous perennials with narrow leaves almost square in section, and solitary, sometimes fragrant purple, yellow or blue flowers in early spring

How to Grow

Cultivation

Grows best in full sun in well-drained soil, or in a bulb frame. See bulb iris cultivation

Propagation

Lift and divide bulbs in early autumn; see bulb propagation

Suggested planting locations and garden types

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

Pruning

No pruning required

Pests

May be susceptible to slugs, snails and thrips

Diseases

May be susceptible to aphid-borne viruses, bacterial soft rot and grey moulds; see Iris diseases