Campanula - Royal Horticultural Society

Final Trials Report
Campanula
2011 – 2013
Trials Office
The Royal Horticultural Society Garden, Wisley, Woking, Surrey, GU23 6QB
RHS Trial of Campanula
Introduction to Campanula
Campanula is a genus of 300 species of annuals, biennials and perennials, some evergreen.
Distribution in the wild is wide, stretching through the temperate zones of the northern hemisphere,
pin particular the regions of southern Europe and Turkey. They grow in diverse habitats, from high
alpine rock crevices and scree down through moorland to meadows and wetland.
Flowers vary in shape, depending on the species from tubular to bell or star shaped or cup and
saucer shaped. They are borne in panicles, racemes or clusters.
This trial has concentrated on herbaceous species including:
C. alliariifolia –
vigorous, clump-forming perennial with heart-shaped leaves and
racemes of pendant, tubular bell-shaped flowers.
C. glomerata –
vigorous, rhizomatous perennial, spreading to form clumps, with ovate,
toothed leaves and dense racemes of tubular, bell-shaped flowers.
C. lactiflora –
upright perennial with ovate, toothed leaves and bell-shaped flowers on
conical panicles. Self seeds freely.
C latifolia –
vigorous, upright perennial with basal clumps of ovate, toothed leaves
on long stems. Flowers are tubular bell shaped.
C. latiloba –
clump forming perennial with basal rosettes of lance-shaped toothed
leaves and short racemes of shallowly cup-shaped flowers.
C. makashvillii –
clump forming perennial with heart shaped flowers and racemes of
open bell shaped flowers.
C. ochroleuca –
compact but spreading perennial with mid green slightly hairy, toothed
leaves which in many situations may be evergreen.
C. persicifolia –
rosette forming rhizomatous perennial with lance shaped toothed
leaves and short terminal racemes of 2-3 slightly pendant cup-shaped
flowers.
C. punctata –
clump forming perennial with creeping rhizomes of ovate dark leaves
and racemes of pendant tubular bell-shaped flowers.
C. rapunculoides –
rhizomatous perennial with narrow toothed leaves and racemes of
pendant tubular bell shaped flowers
C. takesimana –
rapidly spreading rhizomatous perennial with heart shaped toothed
leaves and sprays of bell-shaped flowers.
C. trachelium –
upright woody based perennial with nettle like leaves and racemes of
tubular flowers.
Objectives
The objectives of the trial were:
 To judge for garden worthiness (Award of Garden Merit)
Final Report for Trial No. 1897. – Campanula 2011-13
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To clarify nomenclature
To look at recent cultivars to compare against older ones
To assess resistance to rust
To take herbarium specimens
Judging
The Floral Trials Assessment Forum assessed entries in the trial in 2011, 2012 and 2013,
recommending the Award of Garden Merit to 10 entries and reconfirming 1 existing award using the
following criteria:
 Flower colour and marking
 Reflowering
 Self cleaning
 Rust resistance
 Invasiveness
Entries
There were 76 entries in this trial, submitted as 2 litre plants by breeders, nurseries and individuals in
the UK and Europe.
Cultivation
The plot was rotavated and raked before planting in March 2011. Planting distances were varied
depending on species. A distance of 1m was kept between different species to allow for spread. For
plants of the same species, planting distances were as follows: 30cm between C. trachelium; 60cm
between C. punctate, C. persicifolia, C. ochroleuca, C. alliariifolia, C. rapunculoides, C. latiloba and
C. latifolia; 100cm between C. lactiflora, C. takesimana, C. glomerata and named cultivars.
In the second year of trial, different cultivation techniques were used on the three plants of each
entry. The first plant was staked and deadheaded, the second left to its own devices and the third
was given a Chelsea chop. The Chelsea chop requires a third of new growth to be removed in late
May. This is used to create a more bushy habit, increase vigour and strength and delay flowering for
a longer season. In the third year all plants were left alone.
Staking methods within the trial varied due to the differing habits of species. Twine wrapped around
the plant and secured by bamboo cane worked well as an invisible method, as long as it was
adjusted with plant growth. Birch twigs were used for shorter varieties to form a cage-like structure.
Pest and Disease
A number of pests and diseases were encountered during the trial. It was known that Campanula are
prone to rust and the trial was no different. This was treated with a fungicidal spray in the first two
years, but no treatment was given in the third year. Aphid is also a known problem to Campanula and
this was also encountered on a small scale and treated with an insecticide as and when necessary.
In 2012 powdery mildew was encountered by some entries due to the wet weather. This was treated
with a fungicide spray. Also in 2012 the two spotted spider mite (Tetranychus urticae) was found on a
number of entries and treated using the biological control Phytoseiulus persimilis.
The most frustrating problem encountered during the trial was Sclerotinia spp. as there is no
treatment except the removal of infected plants. Sclerotinia is a fungus that predominantly affects
plants with hollow stems and can be identified by fluffy white fungal growth causing the collapse of
plant stems and dieback.
Final Report for Trial No. 1897. – Campanula 2011-13
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It should be noted that growing so many Campanula together is not common and presents the
difficulties of any monocrop. The RHS trials use pesticides that are for commercial use only and so
cannot advise directly on domestic use. Please see the advisory pages on our website for more
information.
Other Findings
The trial was grown on an exposed site with wind causing damage to plants and in a position of full
sun stressing some entries and reducing performance. The soil was also very rich after so many
years of cultivation which made plants grow larger and lusher than would be expected. Staking was
considered not to be an important consideration in a garden situation as plants would be in a more
sheltered environment with the opportunity to use adjacent plants for any support they did require
which would be lessened in a poorer soil.
Plants Receiving AGMs during theTrial
The following are the plants thought to fulfil the Award of Garden Merit criteria during the trial and to
be worthy of receiving the award. The criteria which a plant needs to fulfil in order to receive the
award are:

excellent for ordinary garden use

available

reasonably resistant to pests and diseases

of good constitution

essentially stable in form and colour

reasonably easy to grow
Hardiness ratings are as follows:
H7 – Hardy in the severest European continental climates including exposed upland locations
in the UK. (Herbaceous and woody plants from continental climates)
Plants Awarded AGM
Campanula persicifolia ‘Pride of Exmouth’
AGM (H7) 2013 [Trial No. 14]
Flowers: July-August Height: 60cm
Comments: “Attractive green eye. Very neat
double. Stands up by itself.”
Sent by World’s End Garden Nursery
Final Report for Trial No. 1897. – Campanula 2011-13
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Campanula lactiflora ‘Platinum’ AGM (H7) 2013
[Trial No. 49]
Flowers: June-August Height: 140cm
“Stands out. Upright. Very pretty, soft flower
colour. Exceptional plants.”
Sent by Orchard Dene Nurseries
Campanula lactiflora ‘Favourite’ AGM (H7)
2013 [Trial No. 51]
Flowers: June-August Height: 120cm
“Good colour. Brilliant foliage. Very floriferous.”
Sent by Hardy’s Cottage Garden Plants
Campanula glomerata ‘Caroline’ AGM (H7)
2013 [Trial No. 70]
Flowers: May-July Height: 45cm
“Masses of flower borne very well above foliage.
Good, erect, stiff stems.”
Sent by Wisley Plant Centre
Campanula glomerata ‘Freya’ AGM (H7) 2013
[Trial No. 73]
Flowers: June-August Height: 35cm
“Lots of bud for plant size. Stunning. Compact.
Reflowers after cutting back.”
Sent by AB-Cultivars B.V
Final Report for Trial No. 1897. – Campanula 2011-13
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AGM Recommended Subject to Availability
Campanula lactiflora ‘Assendon Pearl’ AGM
(H7) 2013 [Trial No. 47]
Flowers: June-August Height. 100cm
“Large individual flowers. Self-supporting. Nice
lilac buds. Delicate scent.”
Sent by Orchard Dene Nurseries
Campanula ‘Blue Delft’ AGM (H7) 2013 [Trial
No. 52]
Flowers: June-Sept Height: 100cm
“Very floriferous. Large flowers. Very good
foliage. Greyness of foliage attractive.”
Sent by Hardy’s Cottage Garden Plants
AGM Recommended Subject to Naming
Campanula persicifolia ‘Hampstead White’
AGM (H7) 2013
[Trial No. 6]
Flowers: June-August Height: 60cm
“Lots of flower. Delicate. Self supporting.”
Sent by World’s End Nursery
Campanula persicifolia AGM (H7) 2013
[Trial No. 12]
Flowers: June-July Height: 90cm
“Intense colour. Lot of flower. Very good clone.
Needs staking.”
Sent by Hardy’s Cottage Garden Plants
Final Report for Trial No. 1897. – Campanula 2011-13
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Campanula latifolia ‘Misty Dawn’ AGM (H7)
2013
[Trial No. 38]
Flowers: June-August Height: 100cm
“Very floriferous. A cracker.”
Sent by Cotswold Garden Flowers
Reconfirmed AGMs
Campanula ‘Kent Belle’ AGM (H7) 2013 [Trial
No. 60]
Flowers: July-Sept Height: 75cm
“Beautiful colour. Better staked. Keeps colour.”
Sent by Bridgemere Nurseries
The following previously awarded Awards of Garden Merit were rescinded:
Campanula latiloba ‘Alba’ [Trial No. 30]
Campanula ‘Burghaltii’ [Trial No. 58]
Trial Index and Senders Details
1
C. trachelium f. alba
Cotswold Garden Flowers
2
C. trachelium 'Bernice'
Hardy's Cottage Garden Plants
3
C. persicifolia 'Best China'
Avondale Nursery
4
C. persicifolia 'Fleur de Neige'
World's End Garden Nursery
5
C. persicifolia 'Gawen'
Cotswold Garden Flowers
6
C. persicifolia 'Hampstead White'
World's End Garden Nursery
7
C. persicifolia 'La Bonne Amie'
Beeches Nursery
8
C. persicifolia 'Powder Puff'
Cotswold Garden Flowers
9
C. persicifolia 'Chettle Charm' PBR
Cally Gardens
10
C. persicifolia 'Chettle Charm' PBR
Hardy's Cottage Garden Plants
Final Report for Trial No. 1897. – Campanula 2011-13
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11
C. persicifolia 'Cornish Mist'
Hardy's Cottage Garden Plants
12
C. persicifolia
Hardy's Cottage Garden Plants
13
C. persicifolia 'La Belle'
Beeches Nursery
14
C. persicifolia 'Pride of Exmouth'
World's End Garden Nursery
15
C. persicifolia 'Blue Bloomers'
Cotswold Garden Flowers
16
C. punctata 'Wedding Bells'
ProperPlants.com
17
C. punctata 'Alina's Double'
World's End Garden Nursery
18
C. punctata 'Pantaloons'
Cotswold Garden Flowers
19
C. punctata 'Pink Chimes' PBR
Beeches Nursery
20
C. punctata f. rubriflora
World's End Garden Nursery
21
C. punctata f. rubriflora 'Wine 'n' Rubies'
Cotswold Garden Flowers
22
C. punctata f. rubriflora 'Vienna Festival'
Cotswold Garden Flowers
23
C. punctata var. hondoensis
Beeches Nursery
24
C. makaschvilii
Cotswold Garden Flowers
25
C. ochroleuca
Cotswold Garden Flowers
26
C. ochroleuca 'Mevrouw von Vollenhove'
Cotswold Garden Flowers
27
C. alliariifolia
Cotswold Garden Flowers
28
C. rapunculoides 'Alba'
Bellflower Nursery
29
C. rapunculoides 'Afterglow'
Cotswold Garden Flowers
30
C. atiloba 'Alba'
Coton Manor Garden
31
C. latiloba 'Splash'
Avondale Nursery
32
C. latiloba
Cotswold Garden Flowers
33
C. latiloba 'Percy Piper'
Bellflower Nursery
33b
C. latiloba 'Percy Piper'
Alan Bloom's Garden
34
C. latiloba 'Highcliffe Variety'
Cotswold Garden Flowers
35
C. latiloba 'Hidcote Amethyst'
ProperPlants.com
36
Campanula x symphyandra
Coton Manor Garden
37
C. Faichem Lilac'
Cotswold Garden Flowers
38
C. latifolia 'Misty Dawn'
Cotswold Garden Flowers
39
C. latifolia 'Eriocarpa'
Alan Bloom's Garden
40
C. rotundiflora var. alaskana
Alan Bloom's Garden
41
C. latifolia 'Gloaming'
Alan Bloom's Garden
42
C. latifolia 'Brantwood'
Cotswold Garden Flowers
43
C. latifolia var. macrantha 'Alba'
Cotswold Garden Flowers
Final Report for Trial No. 1897. – Campanula 2011-13
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44
C. latifolia var. macrantha 'Peter Lewis'
Beeches Nursery
45
C. latifolia var. macrantha
Cotswold Garden Flowers
46
C. lactiflora 'White Pouffe'
Beeches Nursery
47
C. lactiflora 'Ascendon Pearl'
Orchard Dene Nurseries
48
C. lactiflora 'Loddon Anna'
Bridgemere Nurseries
49
C. lactiflora 'Platinum'
Orchard Dene Nurseries
50
C. lactiflora 'Mid Blue'
Orchard Dene Nurseries
51
C. lactiflora 'Favourite'
Hardy's Cottage Garden Plants
52
C. 'Blue Delft'
Hardy's Cottage Garden Plants
53
C. lactiflora 'Pouffe'
Alan Bloom's Garden
54
C. lactiflora 'Prichard's Variety'
Bridgemere Nurseries
54b
C. lactiflora 'Prichard's Variety'
Mr. C. Sanders
55
C.'Crystal'
Avondale Nursery
56
C. 'Pink Octopus' PBR
Cotswold Garden Flowers
57
C.'Van-Houttei'
Cotswold Garden Flowers
58
C.'Burghaltii'
Hardy's Cottage Garden Plants
59
C. 'Viking'
AB-Cultivars B.V.
60
C. 'Kent Belle'
Bridgemere Nurseries
61
C. 'Sarastro'
Hardy's Cottage Garden Plants
62
C. 'Purple Sensation' PBR
Cotswold Garden Flowers
63
C. persicifolia 'Azure Beauty'
Cotswold Garden Flowers
64
C. takesimana 'Alba'
Hardy's Cottage Garden Plants
65
C. takesimana 'Elizabeth II'
Cotswold Garden Flowers
66
C. takesimana 'Elizabeth'
ProperPlants.com
67
C. takesimana
World's End Garden Nursery
68
C. glomerata var. alba
Wisley Plant Centre
69
C. glomerata var. alba 'Schneekrone'
Alan Bloom's Garden
70
C. glomerata 'Caroline'
Wisley Plant Centre
71
C. glomerata 'Emerald'
Wisley Plant Centre
72
C. glomerata 'Joan Elliott'
Alan Bloom's Garden
73
C. glomerata 'Freya'
AB-Cultivars B.V.
74
C. glomerata 'Superba'
Wisley Plant Centre
Final Report for Trial No. 1897. – Campanula 2011-13
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Sender Details
AB-Cultivars B.V., Burg. Tonckensstraat 47, 7921 KB Zuidwolde, The Netherlands
Alan Bloom's Garden, Low Road, Bressingham, Diss, Norfolk, IP22 2AD
Avondale Nursery, 3 Avondale Road, Coventry, West Midlands, CV5 6DZ
Beeches Nursery, Ashdon, Saffron Walden, Essex, CB10 2HB
Bellflower Nursery, Langham Hall, Langham, Bury St Edmunds, Suffolk, IP31 3EE
Bridgemere Garden World, Bridgemere, Nr. Nantwich, Cheshire CW5 7QB
Cally Gardens, Gatehouse of Fleet, Castle Douglas, DG7 2DJ
Coton Manor Garden, Coton, Nr Guilsborough, Northamptonshire, NN6 8RQ
Cotswold Garden Flowers, Sands Lane, Badsey, Evesham, Worcestershire, WR11 7EZ
Hardy's Cottage Garden Plants, Priory Lane Nursery, Freefolk Priors, Whitchurch, RG28 7NJ
Orchard Dene Nurseries, Lower Assendon, Henley on Thames, Oxfordshire, RG9 6AG
ProperPlants.com, Penknight, Lostwithiel, Cornwall, PL22 0JD
World's End Garden Nursery, Moseley Road, Hallow, Worcester, WR2 6NJ
C/o Trials Office: Mr. C. Sanders
The Trials Assessment Forum
This trial was assessed by members of the Floral Trials Assessment Forum who included:
Chairman:
Tony Lord
Vice Chairs: Roy Cheek and Keith Sangster
Members:
Joseph Atkin
Jaime Blake
Val Bourne
Bob Brown
Marina Christopher
David Creese
Ivan Dickings
Tim Fuller
Fergus Garrett
John Gibson
Tony Hender
Philip Morrison
Graham Rice
Chris Sanders
Terry Smale
Mike Smallwood
Ray Waite
Victoria Wakefield
Co-opt:
Sue Wooster
Final Report for Trial No. 1897. – Campanula 2011-13
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Source: Horticultural Trials and Relations,
RHS Garden Wisley, Woking, Surrey GU23 6QB
E-mail: [email protected]
More information about RHS Trials and other colour illustrated reports can be found on
the RHS Website: http://www.rhs.org.uk/trials
Final Report for Trial No. 1897. – Campanula 2011-13
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