Clematis Viticella Group

Final Trials Report

2009 – 2012

Trials Office The Royal Horticultural Society Garden, Wisley, Woking, Surrey, GU23 6QB

Final Report for Trial No.1430 – Clematis viticella 2009-12 1

RHS Trial of Clematis Viticella Goup

Introduction to Clematis Viticella Group Clematis viticella is a deciduous, woody, climbing shrub. Plants in the Viticella Group are either cultivars or hybrids of this plant. Clematis viticella originated in Italy and came to Britain during the reign of Elizabeth I. Flower shapes vary, ranging from bell-shaped and nodding to open and flat to fully double and come in a range of colours from white, red, red-purple, violet and blue. Flowers are produced on the current season’s growth. This group of Clematis have a long flowering period and combine well with other plants. As a climber, it can grow along fences, archways and up trees. They like their roots in the shade and leaves like long days of sunshine. Objectives The objectives of the trial were:

To compare and assess entries and recommend the Award of Garden Merit, to those considered outstanding for garden decoration.

To determine the correct nomenclature.

To prepare herbarium specimens, take photographs and write descriptions as a permanent record to be held in the RHS Herbarium at Wisley.

Judging The Woody Plant Trials Assessment Panel assessed entries in the trial for the Award of Garden Merit from May to September in 2009, 2010 and 2011. Judging was based on the following criteria:

flower quantity : flower quality : length of flowering

Entries There were 69 entries in the trial, two plants per entry, submitted by nurseries and collections from the UK and Holland. A full list of entries can be found at the end of this report. Cultivation The trial was planted out on the 19 February 2009 after which irrigation and garden compost mulch laid. The plants are supported by a chicken-wire cage held by 2.4m (8') canes, with 30cm (1') pushed into the ground. The entries were arranged in rows with 1m between entries. The trial was watered weekly in the first year to aid establishment. Six entries were later added in September 2009. Plants were cut down to 30cm in February of each year and pinched back to four nodes to encourage vigour. In 2011 a bark mulch was laid to lower the pH and to help retain moisture to the roots. Pest and Disease During the trial, plants suffered from powdery mildew due to the dry conditions encountered over the summer months of 2010 and 2011.

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Other Findings During the trial some plants were diagnosed with Clematis green petal. This is a transient disorder related to cold temperatures. Perfectly formed flowers open to reveal a green discolouration and is most commonly found on the first flush of flowers with later flowers unaffected. Pale or white flowers tend to be the most susceptible although earlier flowering varieties can suffer if there are cold temperatures at a critical stage of flower development in spring.

Plants Receiving AGMs During Trial 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: H6 – Hardy in all of UK and northern Europe. Many plants grown in containers will be damaged unless given protection. Temperature range - 20 to -15 ºC

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Plants Awarded AGM

C. ‘Hagelby Pink’ AGM (H6) 2012 [Trial No. 9] votes 10-0 Flowers: June - August Height /Spread: 2-4m Robust, floriferous climber. Mid-green foliage with glabrous, semi-matt leaves and pale violet-pink drooping flowers. “Distinct, floriferous and healthy. Excellent.” Sender: Van Zoest BV

C. ‘Walenburg’ AGM (H6) 2012 [Trial No. 34] votes 10-0 Flowers: June - August Height /Spread: 2-4m Narrowly robust, floriferous climber. Yellow green foliage, glabrous above, lightly hairy on veins underneath. Deep velvety red purple flowers, grading into white ‘cross’ mid petal, becoming wholly white at base. “Very distinct flower, super colour. Good grower.” Sender: J van Zoest BV

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C. ‘Poldice’ AGM (H6) 2012 [Trial No. 39] votes 10-0 Flowers: June - September Height /Spread: 2-4m Very floriferous climber. Yellow gren leaves with young leaves tinged brown. Glabrous above, shiny below. Violet flowers, paler at base, face downwards. “Good foliage, floriferous. Been good for a long time. ” Sender: Roseland House National Collection

C. ‘Aotearoa’ AGM (H6) 2012 [Trial No. 61] Votes 10-0 Flowers: June - August Height /Spread: 2-4m Floriferous, large flowered climber with yellow green foliage tinged red at edges. Rich violet flowers with deeper and lighter tints and a pale mid stripe from base to tip. “Lovely bright stamen. Early flowering. Lovely colour.” Sender: J van Zoest BV

C. WISLEY ‘Evipo001’ AGM (H6) 2012 [Trial No. 69] Votes 6-0 Flowers: July - October Height/ Spread: 2-4m Climber with mid green foliage, glabrous above and hairy beneath. Violet flowers with red flush from base to tip. “Lovely colour. Superb.” Sender: Guernsey Clematis

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Reconfirmed AGMs C. ‘Prince Charles’ AGM (H6) 2012 [Trial No. 17] Votes 10-0 Flowers: June- August Height/ Spread: 2-4m Robust, very floriferous climber. Yellow green foliage edged dark red, glabrous above, sparsely hairy below. Violet flowers with a light pink flush mid petal. “Covered in flower. Good vigour, but useful for smaller gardens.” Sender: Court Farm

C. ‘Abundance’ AGM (H6) 2012 [Trial No. 20] Votes 10-0 Flowers: June - September Height /Spread: 2-4m Tall, robust, very floriferous climber. Mid-green foliage with young leaves strongly flushed brown, glabrous, matt upper, shiny underside. Red purple flowers with darker tints. “Grows well. Lots of flower. Bright colour.” Sender: Thorncroft Clematis Nursery

C. ‘Minuet’ AGM (H6) 2012 [Trial No. 26] Votes 10-0 Flowers: June - August Height/ Spread: 2-4m Very floriferous climber with yellow green, glossy, glabrous leaves. White flowers with purple veins in the centre. “Closely resembles species. Masses of flower.” Sender: J van Zoest BV

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C. ‘Kermesina’ AGM (H6) 2012 [Trial No. 29] Votes 8-0 Flowers: July September Height/ Spread: 2-4m Fine, neat climber with mid green foliage, glabrous above and slightly shiney beneath. Purplish red flowers with redder flush to from middle to tip. “Good landscape impact. Long flowering period.” Sender: Roseland House National Collection

C. ‘Madame Julia Correvon’ AGM (H6) 2012 [Trial No. 31] Votes 13-0 Flowers: June - September Height/ Spread: 2-4m Robust climber with yellow green foliage, glabrous above and lightly hairy on veins below. Rich red purple flowers darkening with age. “Excellent colour. Long flowering period. ” Sender: Ockley Court Farm

C. VIOLET STARGAZER = ‘Venosa Violacea’ AGM (H6) 2012

[Trial No. 42] Votes 10-0 Flowers: June - August Height/ Spread: 2-4m Floweriferous climber with yellow green foliage, slightly glossy above, lightly hairy on veins below. Rich violet flowers, paler at base. “Distinctive. Always outstanding. Beautiful flower.” Sender: Thorncroft Clematis Nursery

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C. ‘Purpurea Plena Elegans’ AGM (H6) 2012 [Trial No. 46] Votes 8-0 Flowers: June - September Height/ Spread: 2-4m Very floriferous climber with yellow green foliage, glabrous and slightly glossy above, hairy beneath. Purple red flowers with unopened petaloid stamens covered in white hair to give frosted appearance. “Very distinctive. Has stood the test of time. Fantastic flower power.” Sender: J van Zoest BV

C. ‘Polish Spirit’ AGM (H6) 2012 [Trial No. 56] Votes 13-0 Flowers: June - October Height/ Spread: 2-4m floriferous climber with mid green foliage, glabrous above, sparsely hairy beneath. Rich purple flowers, aging slightly paler. “Long flowering season. Covered in flower. Superb.” Sender: J van Zoest BV

C. ‘Etoile Violette’ AGM (H6) 2012 [Trial No. 58] Votes 13-0 Flowers: June - October Height/ Spread: 2-4m floriferous climber with mid green foliage, lightly hairy above, moderately hairy below. Rich purple flowers with redder tones mid petal. “Lovely bright stamen. Exciting colour. The best of this type.” Sender: Roseland House National Collection

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The following previously awarded Award of Garden Merit were not reconfirmed:

C. ‘Alba Luxurians’ [Trial No. 4] Sent by Roseland House National Collection C. ‘Pagoda’ [Trial No. 11] Sent by Roseland House National Collection C. ‘Betty Corning’ [Trial No. 15] Sent by Ockley Court Farm C. x triternata ‘Rubromarginata’ [Trial No. 25] Sent by Ockley Court Farm C. ‘Royal Velours’ [Trial No. 52] Sent by J van Zoest BV

Trial Index and Senders Details

1 C. 'Maria Cornelia' J van Zoest BV

2 C. viticella 'Hågelby White' J van Zoest BV

3 C. 'John Treasure' Roseland House National Collection

4 C. 'Alba Luxurians' Roseland House National Collection

5 C .I AM A LADY Q = 'Zoiamladyq' J van Zoest BV

6 C. 'Little Nell' Thorncroft Clematis Nursery

7 C. viticella J van Zoest BV

8 C. 'Chacewater' Roseland House National Collection

9 C. viticella 'Hågelby Pink' J van Zoest BV

10 C. 'Mrs T. Lundell' Roseland House National Collection

11 C. 'Pagoda' Roseland House National Collection

12 C. 'Caerulea Luxurians' J van Zoest BV

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13 C. 'Vanessa' J van Zoest BV

14 C. 'Chatsworth' Liss Forest Nurseries Ltd

15 C. 'Betty Corning' Ockley Court Farm

16 C. 'Emilia Plater' Ockley Court Farm

17 C. 'Prince Charles' Ockley Court Farm

18 C. 'Mary Rose' Ockley Court Farm

19 C. 'Foxtrot' Roseland House National Collection

20 C. 'Abundance' Thorncroft Clematis Nursery

21 C. 'Etoile Rose' J van Zoest BV

22 C. 'Pendragon' J van Zoest BV

23 C. 'Tango' Roseland House National Collection

24 C. 'Cicciolina' J van Zoest BV

25 C. x triternata 'Rubromarginata' Ockley Court Farm

26 C. 'Minuet' J van Zoest BV

27 C. 'Margot Koster' Ockley Court Farm

28 C. 'Carmencita' Roseland House National Collection

29 C. 'Kermesina' Roseland House National Collection

30 C. 'Kermesina' Ockley Court Farm

31 C. 'Madame Julia Correvon' Ockley Court Farm

32 C. 'Kermesina' J van Zoest BV

33 C. 'Södertälje' J van Zoest BV

34 C. 'Walenburg' J van Zoest BV

35 C. 'Kaaru' J van Zoest BV

36 C. 'Little Butterfly' J van Zoest BV

37 C. I AM A LITTLE BEAUTY = 'Zolibe' J van Zoest BV

38 C. 'Odoriba' J van Zoest BV

39 C. 'Poldice' Roseland House National Collection

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40 C. 'Entel' J van Zoest BV

41 C. 'Hanna' Ockley Court Farm

42 C. 'Venosa Violacea' Thorncroft Clematis Nursery

43 C. 'Jenny' J van Zoest BV

44 C. 'Jorma' J van Zoest BV

45 C. 'Viola' J van Zoest BV

46 C. 'Purpurea Plena Elegans' J van Zoest BV

47 C. 'Purpurea Plena Elegans' Roseland House National Collection

48 C. 'Purpurea Plena Elegans' Thorncroft Clematis Nursery

49 C. 'Elvan' Roseland House National Collection

50 C. viticella J van Zoest BV

51 C. 'Little Bas' Roseland House National Collection

52 C. 'Royal Velours' J van Zoest BV

53 C. 'Dark Eyes' J van Zoest BV

54 C. 'Kiev' J van Zoest BV

55 C. 'Blue Belle' Roseland House National Collection

56 C. 'Polish Spirit' J van Zoest BV

57 C. 'Polish Spirit' Thorncroft Clematis Nursery

58 C. 'Étoile Violette' Roseland House National Collection

59 C. 'Black Prince' Roseland House National Collection

60 C. 'Mikelite' J van Zoest BV

61 C. 'Aotearoa' J van Zoest BV

62 C. 'Negritianka' J van Zoest BV

63 C. 'Romantika' J van Zoest BV

64 C. AVANT-GARDE = 'Evipo033' Guernsey Clematis

65 C. BONANZA = 'Evipo031' Guernsey Clematis

66 C. CONFETTI = 'Evipo036' Guernsey Clematis

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67 C. GALORE = 'Evipo032' Guernsey Clematis

68 C. PALETTE = 'Evipo034' Guernsey Clematis

69 C. WISLEY = 'Evipo001' Guernsey Clematis

Sender Details

Guernsey Clematis Nursery, Domarie, Vineries Les Sauvages, St Sampson, Guernsey, GY2 4FD

J. van Zoest BV, Reijerskoop 148, 2771 BT Boskoop, Holland

Liss Forest Nursery Ltd, Petersfield Road, Liss, Hampshire GU33 6HA

Ockley Court Farm, Ockley, Nr Dorking, Surrey RH5 5LS

Roseland House National Collection of Clematis, Roseland House, Chacewater, Truro, Cornwall, TR4 8QB Thorncroft Clematis Nursery, Norfolk, NR9 4QG

Source: Horticultural Trials and Relations, RHS Garden Wisley, Woking, Surrey GU23 6QB

E-mail: trials@rhs.org.uk

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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