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)

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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.

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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

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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

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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

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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

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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

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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

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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

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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

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