RHS PLANT TRIALS BULLETINNumber 22 September 2008

RHS PLANT TRIALS BULLETINNumber 22 September 2008

Chilli PeppersJacquie GrayTrials Officer, RHS Garden Wisley

Michael MichaudChilli Specialist

Chilli PeppersJacquie GrayTrials Officer, RHS Garden Wisley

Michael MichaudChilli Specialist

The more familiar of the two are the spice-type chillies,which have relatively small, thin-fleshed fruit valued mainlyfor their pungency. Essential in Thai, Indian and Caribbeancooking, they include the cayenne variety and are normallyadded to dishes in such small quantities that, except fortheir heat, they usually go unnoticed. In contrast are thevegetable-types that have larger fruits with thicker flesh.They can be fried, stuffed, or added to salads like sweetpeppers, and bring both heat and substance to a recipe

Fruit colour, too, is a variable trait that differs according toboth cultivar and stage of ripeness. Depending on thecultivar, unripe fruit are normally a shade of green rangingfrom light lime to almost black, though they are sometimespale yellow, a hue of purple or a mix of the two. The colourschange as the fruit ripen, turning red, yellow, orange or, lesscommonly, brown.

The growth habits of the plants themselves also varydepending on cultivar and the cultivation methodsimposed on the plants. Some cultivars, for example, arenaturally short and compact, others look like shrubs, andstill others grow tall and gangly. Planting in pots ratherthan in the ground often reduces plant size, whilepinching out the growing tips of young plants can makethem bushier.

by Michael Michaud

RHS Trial of Chilli PeppersIn 2006 the Royal Horticultural Society, as part of acontinuing assessment of new and established cultivars forcultivation in an unheated plastic tunnel, held a trial ofchilli peppers. RHS vegetable trials are conducted as part ofour charitable mission to inform, educate and inspire allgardeners, with good, reliable cultivars recognised by theAward of Garden Merit after a period of trial.

ObjectivesThe trial aimed to compare and evaluate a range ofavailable chilli pepper cultivars and to demonstrate thecultivation of this crop in an unheated plastic tunnel. TheVegetable Trials Sub-Committee assessed the entries andoutstanding cultivars for garden use were given the Awardof Garden Merit. Entries were also described andphotographed to provide a lasting record in the RHSHerbarium at Wisley.

EntriesThere were 51 entries in the trial submitted by various seedcompanies in the UK, Europe and USA. These were allgrown at Wisley, with the 40 Capsicum annuum entries alsogrown at East Ruston Old Vicarage Garden.

Introduction to ChilliesOriginating in the New World, chillies have becomeuniversal culinary essentials since Columbus’ voyages ofexploration. Grown mainly for their edible fruit, they arethe pungent relatives of sweet peppers and, botanically,include the five domesticated species of the genusCapsicum:

� Capsicum annuum, the most common of thedomesticated species, includes sweet bell peppers andmany of the cultivated chillies.

� C. chinense, includes the hottest chillies ever measuredsuch as the Caribbean ‘Scotch Bonnet’ and Bangladeshi‘Naga Morich’.

� C. frutescens, best known for the world famous TabascoGroup chillies.

� C. baccatum, commonly called aji throughout SouthAmerica.

� C. pubescens, with characteristic dark purple seeds.

The pungency in chillies is caused by a group of chemicalscalled capsaicinoids. These chemicals are found only in thefruit, and the more concentrated they are, the morepungent the chilli is. Their concentration is governedmostly by the choice of cultivar, though levels are alsoinfluenced by growing conditions and age of the fruit.

The degree of pungency is expressed in Scoville Heat Units(SHU), named after Wilbur Scoville, an Americanpharmacologist who devised a test for measuring chillipungency in 1912. The scale starts at zero for sweet peppers,which have no heat, and increases up to the current recordholders – versions of C. chinense from Bangladesh, Assamand the Caribbean – which have reached pungency levelsranging from about 855,000 to over 1,000,000 SHU.

Chilli fruit differ not only in pungency levels but also incertain physical features that determine their use incooking. Cultivars can be broadly divided into twoculinary types, though once in the kitchen, the distinctionbetween them is often blurred.

RHS Trial of Chilli Peppers

RHS Plant Trials Bulletin2

Front cover: C. annuum ‘Fiesta’(Photo Linda Jones)

Left: RHS Trial of chilli peppersat Wisley

Right: C. annuum ‘FirecrackerPiquin‘

Far Right: Members of the Sub-Committee assessing the trialwith Michael Michaud

Chilli Peppers 3

C. chinense ‘Antillais Caribbean’

C. annuum ‘Apache’

C. annuum ‘Demon Red’

C. annuum ‘Etna’

C. annuum ‘Fiesta’

C. annuum ‘Filus Blue’

C. annuum ‘Firecracker Piquin’

C. annuum ‘Fresno’

C. annuum ‘Fuego’

C. chinense Habanero Group

C. annuum ‘Hungarian Hot Wax’

C. annuum ‘Navaho’

C. annuum ‘Prairie Fire’

C. annuum ‘Summer Heat’

C. annuum ‘Super Chili’

C. annuum ‘Thai Dragon’

C. annuum ‘Tricolor Variegatum’

H2 = requires unheated glass

Award of Garden Merit Chilli PeppersThe trial was assessed for the Award of Garden Merit bythe Vegetable Trials Sub-Committee using the followingcriteria:

� ease of cultivation

� early maturity

� size of plant

� quality

� appearance / ornamental value

� culinary usefulness

Results of the TrialSeventeen chilli pepper cultivars received theAward of Garden Merit H2

RHS Plant Trials Bulletin4

Pests and DiseasesThe main pests of this crop are whitefly, thrips and redspider mite. Encarsia formosa was introduced regularly tocontrol the whitefly and one bag of Amblyseius per plantwas used to control thrips. Red spider mite did not affectthe trial, but regular misting would have deterred this pest.

FindingsThe plants grew more vigorously and the fruits ripenedquicker at Wisley than at East Ruston, where thetemperatures were lower. Chilli fruits ripen once they havereached full size. In Capsicum annuum plant growthvirtually stops when temperatures drop to 10ºC/50ºF, whiletemperatures above 30ºC/86ºF can reduce production.Good light levels are also important.

As well as selecting cultivars for the Award of GardenMerit, the Sub-Committee highlighted other entries thatare valued by chilli enthusiasts and connoisseurs. Thesecould not be recommended for the award because theycrop too late to be really useful in the UK or require morespecialised cultivation. The Sub-Committee also noted thatmany chilli pepper plants are ornamental and valued forgarden decoration: colourful and highly decorative ‘PrairieFire‘ has a compact habit, suitable for pots; ‘Joe’s Long’produces exceptionally long fruits, grown for their noveltyvalue as well as for culinary use.

CultivationSeed was sown into p84 modules, two per cell, using peat-reduced modular compost, watered in with Revive (aproduct that contains natural soil micro-organisms whichencourage soil fertility and healthy plant growth) andprovided with 23-25ºC of bottom heat until germinated.Sowing of the later fruiting cultivars (those other thanCapsicum annuum) took place on 30 January 2006.Capsicum annuum entries were sown on 24 February. Oncegerminated, seedlings were provided with supplementarylighting to simulate a 16 hour day and thinned to oneplant per cell. Seedlings were later potted on into 9cm potsof peat-reduced compost, watered with Revive and grownon in a glasshouse where a biological control programmewas used to combat aphids, white fly, red spider mite andthrips. From 27 April, as they became large enough, theentries were planted singly into 3ltr/18cm pots of gardensoil. At East Ruston Old Vicarage Garden the plants werepotted using compost and stood out in the Orangery.

The potted plants were plunged into hand-cultivated soilin a plastic tunnel on 15 May, side-by-side, 44cm apart inrows 75cm apart. Paths 120cm wide ran the length of theplastic tunnel between the double rows of entries. The potsprovided some restriction to the roots so that the plantsdid not become overly large or lush. Four plants of eachentry were grown. A drip irrigation system was installed,which meant plants could be given a liquid feed through adiluter.

Above: Young plantsin the PropagationDepartment

Above right: ‘PrairieFire’

Right: ‘Joe’s Long’

RHS Trial of Chilli Peppers

Chilli Peppers 5

Capsicum chinense ‘AntillaisCaribbean’Sent by A L Tozer Ltd.

Quite small, blocky, bright redfruits are aromatic and extremelyhot. Similar chillies are widelyused in South American andCaribbean cooking. Latercropping, it is best sown inJanuary.

Plant height 90cm. Blocky, lanternshaped fruits are 3cm wide, 6cmlong and hang downwards on theplant. Fruit ripe from 23 July;average of 26 fruits picked from oneplant by 15 August.

Award of Garden Merit Chilli Peppers

Capsicum annuum ‘Apache’Sent by D T Brown & Co.

A decorative, bushy plant; it doeswell in both large and small pots.Produces a large crop of small,juicy, hot peppers that ripen frombright green to red and are heldoutwards from the stems.

Plant height 45cm. Small, taperingfruits are 1.5cm at widest, 4cm longand are held up and outwards. Fruitripe from 23 July; average of 103fruits picked from one plant by 15August.

Capsicum annuum ‘Demon Red’Sent by John Bertinat Seeds Ltd.

A small, ornamental plant that isstarred with white flowers, itproduces an abundant crop oftiny upward pointing fruits thatmature to a strong, bright red.Fruits are hot and ideal for Thaicooking.

Plant height 35cm. Tiny, tapering,thin-walled fruits are 0.5cm atwidest, 4cm long. Fruit ripe from 23July; average of 366 fruits pickedfrom one plant by 15 August.

Capsicum annuum ‘Etna’Sent by Mr Fothergill’s Seeds.

Attractive bunches of shinypeppers that mature from brightmid-green to red, are carried erecton compact plants that aresuitable for growing in pots.Produces a good crop of very hotpeppers.

Plant height 75cm. Small, taperingfruits are 1.25cm at widest, 5cmlong and held upwards. Fruit ripefrom 23 July; average of 18 fruitspicked from one plant by 15 August.

Capsicum annuum ‘Fiesta’Sent by Mr Fothergill’s Seeds.

Highly ornamental plants arestarred with white flowers andcovered in jewel-like, smallconical fruits that ripen throughpurple, yellow and orange tobright red. Excellent decorativeplant for growing in pots.

Plant height 80cm. Small conicalfruits are 2.5cm at widest, 6cm longand held upwards. A spice type, thefruits are hot to very hot. Fruit ripefrom 23 July; average of 56 fruitspicked from one plant by 15 August.

Capsicum annuum ‘Filus Blue’Sent by W Robinson & Son (Seeds& Plants) Ltd.

Attractive, highly ornamentalplants. The young leaves are mid-green becoming very dark greenwith a purple flush and the plantsare covered with purple, orangeand bright red fruits that are spicyand moderately hot.

Plant height 45cm. Purple-flowered.Very small, cherry shaped fruits are1.5cm wide, 2cm long and heldupwards on the plant. Fruit ripe from23 July; average of 68 fruits pickedfrom one plant by 15 August.

Photo by Sarah Wain

Award of Garden Merit Chilli Peppers

RHS Plant Trials Bulletin6

Capsicum annuum ‘FirecrackerPiquin’Sent by Western Hybrid Seeds Inc.

Very ornamental, uniform plantswith small, very hot peppers thatare held upright and give anattractive sunset display oncethey have matured beyondpurple.

Plant height 70cm. Small, conicalfruits are 2.5cm at widest, 3.5cmlong. Colour changes from purple toyellow, then orange to red. Fruit ripefrom 23 July; average of 29 fruitspicked from one plant by 15 August.Also sold in catalogues as ‘FireCracker’.

Capsicum annuum ‘Fresno’Sent by Bakker Brothers.

Fairly short, upright growingplants are very productive. Theconical fruits ripen from lightgreen to deep scarlet-red, withmedium-thick flesh that is veryhot.

Plant height 80cm. Conical fruitsare 2.5cm at widest, 9cm long andheld upwards on the plant. Fruit ripefrom 23 July; average of 38 fruitspicked from one plant by 15 August.

Capsicum annuum ‘Fuego’Sent by Elsoms Seeds Ltd.

Good yield of early, easy-to-harvest, big, red fruits areproduced on plants with an opengrowth habit. A hot pepper withthick, meaty flesh.

Plant height 110cm. Tapering fruitsare 3cm at widest, 17cm long andhang downwards. Fruit ripe from 23July; average of 23 fruits picked fromone plant by 15 August

Capsicum chinense HabaneroGroupSent by Simpson’s Seeds.

Very attractive, blocky, orangefruits are extremely hot. Plants arequite compact, give a good yieldand are suitable for growing inpots. Later cropping, it is bestsown in January.

Plant height 70cm. Blocky, lantern-shaped fruits are 3.5cm wide, 6cmlong and hang downwards. Fruit ripefrom 23 July; average of 35 fruitspicked from one plant by 15 August.

Capsicum annuum ‘HungarianHot Wax’Sent by Mr Fothergill’s Seeds andby W Robinson & Son (Seeds &Plants) Ltd.

The versatile fruits are medium-hot and can be used as a spicyalternative to sweet peppers.Suitable for pot cultivation, theseare one of the easiest chillies togrow.

Plant height 100cm. Tapering fruitsare 3cm at widest, 13cm long.Immature fruits are pale yellow,maturing to red and hangdownwards. Fruit ripe from 23 July;average of 15 fruits picked from oneplant by 15 August.

Capsicum annuum ‘Navaho’Sent by E W King & Co Ltd.

Sturdy plants with stiff stems thatcarry the fruits well. The large,thick-fleshed, semi-hot peppersare perfect for stuffing. Theflavour and heat increases as theyripen to bright red.

Plant height 130cm. Tapering fruitsare 3cm at widest, 14cm long andhang downwards. Fruit ripe from 28July; average of 6 fruits picked fromone plant by 15 August.

Chilli Peppers 7

Capsicum annuum ‘Prairie Fire’Sent by A L Tozer Ltd.

Very attractive, short, spreadingplants are covered in a mass ofvery small, upward-pointingpeppers that ripen from cream,through yellow and orange to red.Ideal in pots and super for awindowsill. The small peppers arevery hot.

Plant height 20cm. Small, taperingfruits are 1cm at widest, 3cm long.Fruit ripe from 23 July; average of 56fruits picked from one plant by 15August.

Capsicum annuum ‘Summer Heat’Sent by A L Tozer Ltd.

Reliably early, hot, jalapeño typepepper. The surface of the fruit isprone to corky cracks andstriations, which is a traitsupposedly valued by Mexicancooks.

Plant height 100cm. Gentlytapering, red fruits are 3cm atwidest, 8cm long and hangdownwards. Fruit ripe from 23 July;average of 15 fruits picked from oneplant by 15 August.

Capsicum annuum ‘Super Chili‘Sent by A L Tozer Ltd.

Ornamental plants; well suited togrowing in pots. Produces a highyield of very hot, thin-walledfruits that are held upright andripen from light green to red.

Plant height 50cm. Small, taperingfruits are 1cm at widest, 6cm longand hang downwards. Fruit ripefrom 23 July; average of 58 fruitspicked from one plant by 15 August.

Capsicum annuum ‘Thai Dragon’Sent by A L Tozer Ltd.

Very hot pepper used in Thaicooking. Plants fruit prolifically,but tend to be rather rampantand may need tying. Alsoresponds well to stopping.

Plant height 140cm. Long, taperingfruits that ripen from green to red,are 1cm at widest, 8cm long andhang downwards on the plants. Fruitripe from 23 July; average of 71fruits picked from one plant by 15August.

Capsicum annuum ‘TricolorVariegatum’Sent by W Robinson & Son (Seeds& Plants) Ltd.

Ornamental foliage is anattractive mid-green, splashedcream and purple. Small fruitsmature from purple, throughorange to red. Plants have a ratherspreading habit, but can bepruned to shape.

Plant height 70cm. Small taperingfruits are hot to very hot, 1.5cm atwidest, 3cm long and hangdownwards on the plants. Fruit ripefrom 23 July; average of 19 fruitspicked from one plant by 15 August.

Orangery at East RustonVicarage (Photo Ali Cundy)

For chilli enthusiasts and connoisseurs

RHS Plant Trials Bulletin8

Capsicum baccatum ‘Lemon Drop’

A very hot, lemony-flavoured, ajitype, reportedly from Peru

Plant height 150cm. Tapering fruits ripenfrom pale green to yellow, are extremelyhot, 2cm at widest, 8cm long and hangdownwards on the plants. Fruit ripe from23 July; average of 108 fruits picked fromone plant by 15 August.

Capsicum frutescens Tabasco Group

Used in Creole cooking and to makethe famous hot Tabasco Sauce ®

Plant height 120cm. Small tapering fruitsripen from pale green to red, areextremely hot, 0.5cm at widest, 3cm longand held upwards on the plants. Fruitripe from 23 July; average of 19 fruitspicked from one plant by 15 August.

Capsicum annuum ‘Pasilla Bajio’

The dried pods are mild to moderatelyhot and form the basis for molesauces. When used fresh, chillies ofthis sort are called chilacas and used inenchiladas, chilli sauces, soups, andstews

Plant height 170cm. Fruits ripen fromdark green to dark brown, are 6cm atwidest, 11cm long and hang downwards.First fruits fully grown by 1 August;average of 22 fruits picked while stillgreen from one plant by 15 August.

Cultivars Culinary type Plant Colour Shape type Size

*and Uses height** change to and Heat

maturity

Capsicum chinense Spice. South American 90cm 3cm x 6cm‘Antillais Caribbean’ and Caribbean dishes.

Capsicum annuum Spice. Cooking and 45cm 1.5cm x 4cm‘Apache’ ornamental plants.

Capsicum annuum Spice. Thai dishes. 35cm 0.5cm x 4cm‘Demon Red’ Ornamental plants.

Capsicum annuum Spice. 75cm 1.25cm x 5cm‘Etna’

Capsicum annuum Spice. Cooking and 80cm 1.5cm x 6cm‘Fiesta’ highly ornamental plants.

Capsicum annuum Spice. Cooking and 45cm 1.5cm x 2cm‘Filus Blue’ highly ornamental plants.

Capsicum annuum Spice. Cooking and 70cm 2.5cm x 3.5cm‘Firecracker Piquin’ highly ornamental plants.

Capsicum annuum Spice and vegetable. 80cm 2.5cm x 9cm‘Fresno’ Stews, salads and

fresh in salsas.

Capsicum annuum Vegetable. 110cm 3cm x 17cm‘Fuego’

Capsicum chinense Spice. 70cm 3.5cm x 6cmHabanero Group

1 fruit = mild

5 fruits = extremely hot)

Size = (width × length)

Selection guide

Chilli Peppers 9

* Spice types are relatively small-fruited with thinflesh; vegetables types have fruits that are largerwith thicker flesh.

** Measured during the first week of August 2006

Cultivars Culinary type Plant Colour Shape type Size

*and Uses height** change to and Heat

maturity

Capsicum annuum Vegetable. Frying, 100cm 3cm x 13cm‘Hungarian Hot Wax’ stuffing and using in

salads.

Capsicum baccatum Spice. Citrus-flavoured 150cm 2cm x 8cm‘Lemon Drop’ aji type; reportedly

from Peru.

Capsicum annuum Vegetable. Stuffing. 130cm 3cm x 14cm‘Navaho’

Capsicum annuum Spice and vegetable. 170cm 3cm x 18cm‘Pasilla Bajio’ Fresh or dried in Mexican

cooking, for dishessuch as enchiladas,chilli and mole sauces.

Capsicum annuum Spice. Cooking and 20cm 1cm x 3cm‘Prairie Fire’ ornamental plants.

Capsicum annuum Vegetable. 100cm 3cm x 8cm‘Summer Heat’ Mexican dishes.

Capsicum annuum Spice. 50cm 1cm x 6cm‘Super Chili’

Capsicum annuum Spice. 140cm 1cm x 8cm‘Thai Dragon’

Capsicum annuum Spice. 70cm 5cm x 3cm‘Tricolor Variegatum’

Capsicum frutescens Spice. Dry, hot smoky 120cm 0.5cm x 3cmTabasco Group flavour. Creole cooking

and Tabasco Sauce ®.

RHS Plant Trials Bulletin10

1 fruit = mild5 fruits = extremely hot)Size = (width × length)

Selection guide * Spice types are relatively small-fruited with thinflesh; vegetables types have fruits that are largerwith thicker flesh.

** Measured during the first week of August 2006

Kings Seeds, Monks Farm, Kelvedon, Essex CO5 9PG.www.kingsseeds.com

Moles Seeds(UK) Ltd., Turkey Cock Lane, Stanway, EssexC03 8PD. www.molesseeds.co.uk

Mr Fothergill’s Seeds Ltd, Gazeley Road, Kentford, SuffolkCB8 7QB. www.fothergills.co.uk

The Real Seed Catalogue, Brithdir Mawr Farm, Newport,Nr. Fishguard, Pembrokeshire SA42 0QJ.www.realseeds.co.uk

Seeds of Italy, Unit 3 Phoenix Industrial Estate, RosslynCrescent, Harrow, Middx HA12 2SP. www.seedsofitaly.com

Simpson’s Seeds, Walled Garden Nursery, Horningsham,Wiltshire, BA12 7NQ. www.simpsonsseeds.co.uk

Suffolk Herbs, Monks Farm, Pantlings Lane, CoggeshallRoad, Kelvedon, Colchester, Essex CO5 9PG.www.suffolkherbs.com

Suttons Consumer Products Ltd., Woodview Road,Paignton, Devon TQ4 7NG. www.suttons.co.uk

Thompson & Morgan Ltd, Poplar Lane, Ipswich, SuffolkIP8 3BU. www.thompson-morgan.com

W Robinson & Son (Seeds & Plants) Ltd., Sunny Bank,Forton, Lancs. PR3 0BN. www.mammothonion.co.uk

Western Hybrid Seeds Inc, P O Box 1169, Hamilton City,CA 95951, USA

AcknowledgementsMichael Michaud, ethnobotanist and chilli specialist

Jim England and staff in Trials at RHS Garden Wisley

Guy Barter, Head of Horticultural Advisory Service

Further readingBiggs, T. (2003) Growing Vegetables – The RHS Encyclopaediaof Practical Gardening. Mitchell Beazley, London

DeWitt, D. & Bosland, P.W. (1993) The Pepper Garden.Ten Speed Press, Berkeley, California

Pollock, M. (2002) RHS Fruit & Vegetable GardeningDorling Kindersley, London

RHS Trials.Michaud, M. (2007) Turn up the heat. The Garden 132(4):238-241

RHS Journals onlinehttp://www.rhs.org.uk/Learning/Publications/pubs/garden0407/chilli.htm

Useful websitesRHS Gardening Advice on growing Chilli Peppershttp://www.rhs.org.uk/advice/profiles0302/chillies.asp

Vegetable Trials Sub-CommitteeChairman: Colin Randel

Vice Chairman: Peter Dawson

John Barker Tony HewittRon Butler David JefferyBill Chowings Steve MercerPaul Corfield Sarah WainMike Day Ron WattsDerrick Fuller Tony WilkieIan Gillott Medwyn Williams

Chilli specialist: Michael Michaud

Chilli Peppers 11

Above: MichaelMichaud

Right: RHS Trial ofChilli Peppers atWisley

Senders of seed to the trialAddresses of Senders

A L Tozer Ltd., Pyports, Downside Bridge Road, Cobham,Surrey KT11 3EH. www.tozerseedsdirect.com

Bakker Brothers, PO Box 7, 1723 ZG Noord-Scharwoude,Netherlands.

D T Brown, Bury Road, Kentford, Suffolk CB8 7PR.www.dtbrownseeds.co.uk

Elsoms Seeds Ltd., Pinchbeck Road, Spalding,Lincs. PE11 1QG.

Floranova Ltd., Norwich Road, Foxley Dereham, NorfolkNR20 4SS.

John Bertinat Seeds, 39 Bure Way, Aylsham, Norfolk,NR11 6HL.

Johnsons Seeds, Kentford, Newmarket, Suffolk CB8 7QB.www.johnsons-seeds.com

RHS Plant TrialsWith so many different types of gardener and so manydifferent cultivars available to them in each group ofplants, it is important that a system of recommendation isin place to help with selection at point of sale. Theserecommendations must be clear and reliable to ensure thatof the thousands of plants available in the UK, aproportion are known to be excellent garden plants. TheRHS provides this information through its extensiveprogramme of plant trials held at RHS gardens in the UK.The RHS Award of Garden Merit signifies the selectionof the best cultivars for general garden use.

RHS plant trials serve the professional gardener who wantsto know the range of plants available, including the latestbreeding and selection programmes, with their distinctivecharacteristics and provenance. They also serve theamateur who wants to know which plants will grow andperform well in a particular garden situation.

The RHS has an unrivalled resource of knowledge andexpertise and is therefore best placed to conduct planttrials for the UK gardening market.

RHS Trials BulletinsBegonia Rex Cultorum Group: Number 16Canna: Number 3Clematis alpina & C. macropetala: Number 21Daisies (yellow perennial): Number 6Delphinium: Number 5Fuchsia (hardy): Number 12Geranium (hardy) Stage 1: Number 10Geranium (hardy) Stage 2: Number 14Geranium (hardy) Stage 3: Number 18Hyacinthaceae (little blue bulbs): Number 11Iris (bearded): Number 17Lavenders (hardy): Number 2Miscanthus : Number 7Peppers (sweet): Number 15Potatoes (salad): Number 8Potentilla (shrubby): Number 1Rhododendron yakushimanum and hybrids: Number 13Runner Beans: Number 19Saxifrages (silver): Number 9Sedums (herbaceous): Number 20Spiraea japonica (with coloured leaves): Number 4

These bulletins can be viewed at a larger size on theRHS Website: www.rhs.org.ukplants/trials_bulletins.asp

RHS Plant Trials and AssessmentsOnline publications, to complement the RHS PlantTrials Bulletins series

Caryopteris: Number 2Perovskia: Number 3Pittosporum tenuifolium hybrids and cultivars: Number 1

Trials indexes can be obtained from The Trials Office,RHS Garden Wisley, Woking, Surrey GU23 6QB,Email: trials@rhs.org.ukTrials reports on the web atwww.rhs.org.uk/plants/award_plants.asp

The Royal Horticultural SocietyThe RHS is the UK’s leading gardening charity dedicated toadvancing horticulture and promoting good gardening. Itscharitable work includes providing expert advice andinformation, advancing horticulture, training the nextgeneration of gardeners, helping school children learnabout plants, and conducting research into plants, pestsand environmental issues affecting gardeners. The RHSAGM plant trial scheme is an important part of this work.

The RHS receives no government grants and for everypound received from members’ subscriptions we need toraise more than twice as much again to fund our charitablework. We also rely on donations and sponsorship tosupplement income from our garden operations, flowershows, shops and plant centres.

RHS HerbariumThe RHS Herbarium keeps a record of trial cultivars as driedspecimens with detailed descriptions and photographicimages. This forms an important reference for thehorticultural industry. Any new cultivars are highlightedand a nomenclatural standard specimen is preserved anddescribed.

The RHS Herbarium, stored at RHS Garden Wisley, is thelargest active horticultural herbarium in the world. Atpresent the collection contains about 80,000 herbariumspecimens and over 40,000 images of plants. Material isactively collected from a wide spectrum of sourcesincluding RHS plant trials.

The RHS, the UK’s leading gardening charity

RHS Garden, WisleyWokingSurreyGU23 6QBe-mail: trials@rhs.org.uk

www.rhs.org.uk/trials

Reg charity no. 222879in Scotland SCO38262

All text and images Copyright RHS 2008 except whereotherwise stated.

ISSN 1477-9153 (print)ISSN 1447-9161 (online)

Printed by Trident Printing (ISO14001)using FSC accredited materials – TT-COC-002508

This bulletin is printed using vegetable-based inks on paper madefrom 80% recycled fibre. Suitable for recycling