Caryopteris x clandonensis 'Heavenly Blue'

About this cultivar:

Caryopteris x clandonensis 'Heavenly Blue' is an oldie but a goodie. Apparently very similar (possibly identical) to the original Caryopteris x clandonensis introduction from Arthur Simmonds.

The 2007 RHS Trial notes say: 'A bushy to erect plant with reddish stems and rather large, grey-green leaves with a few teeth near the apex. Flowers mid to dark blue. Very large turquoise to pale blue fruiting calyx. Raised in Wayside Gardens, Ohio, USA in 1953.'

The Applied Plant Research station at Boskoop (Holland) in cooperation with the Royal Boskoop Horticultural Society undertook a trial of Caryopteris and 'Heavenly Blue' was rated in 2006 as 'Very Good'.

Nice at the front of a border or path, insects seem to love it.

• Position: Full sun, partial shade
• Soil: Almost any soil, grows well in Ballyrobert
• Flowers: August, September
• Other features: Grows well in Ballyrobert
• Hardiness: H4 - Hardy through most of the UK (-10 to -5°C), Fully hardy - grows well in Ballyrobert!
• Habit: Bushy, Clump forming
• Foliage: Deciduous
• Height: 50 - 100 cm  (1.5 - 3.25 ft)
• Spread: 100 - 150 cm  (3.25 - 5 ft)
• Time to full growth: 5 to 10 years
• Plant type: Herbaceous Perennial, Shrub
• Colour: Blue, green
• Goes well with: Aster, Abutilon, Agastache and Solidago (for Autumn). You can also think about Achillea, Artemisia, and some Anemone.
  

About this genus:

Caryopteris (also called bluebeard) is a genus of flowering plants  native to eastern Asia (China, Korea, Japan, Mongolia). They are herbaceous plants or small shrubs growing to 1–4 m tall. Usually somewhere in between. The often aromatic and often varigated foliage combined with the blue or white flowers surrounded by butterflies and bumblebees make many Caryopteris a gardeners dream come true.

Though several Caryopteris species are grown in botanical gardens, as ornamental plants the species have largely been superseded in gardens by the hybrid Caryopteris × clandonensis (C. incana × C. mongholica). The accidental cross that produced it occurred in the garden of Arthur Simmonds at Clandon, near Guildford, Surrey. In 1930, wishing to propagate C. mongholica, he gathered seeds from a plant that was growing near C. mastacanthus. When the seedlings eventually flowered in their second year, hybrids apeared. The final selection, however, was made of a self-sown volunteer that appeared under C. mastacanthus, and eventually smothered it. It began winning Royal Horticultural Society medals in 1933. Caryopteris × clandonensis is often a small, deciduous, aromatic shrub has grey-green leaves and produces masses of blue flowers in late summer.

In the textbooks Caryopteris  prefer well-drained soil, prefer dry conditions and do not tolerate heavy, wet soils. You should tell that to the cultivars in our garden - they do fine in our heavy clay and under our overcast skies! I reckon the cultivars we have found should do anywhere that isn't full shade or waterlogged.

Caryopteris combine well with other  Autumnal plants such as Aster, Abutilon, Agastache and Solidago. You can also think about Achillea, Artemisia, and some Anemone