The list is usually cut to a shortlist of 20 before the winner is announced on 23 May after the shortlist is selected on 22 May.
On the long list are 25-British-bred plants, 11 Dutch-bred plants, three French-bred plants, two US-bred plants and three German-bred plants.
Peter Seabrook’s HTA/GCA-backed Sun Flower Square has five plants in the competition among 40 new plants that will be on the display.
Hardy’s Cottage Garden Plants has five new plants entered, while Thompson & Morgan has three plants in the competition.
There are four roses in the competition including Harkness’ ‘Mary Berry’, as well as five heucheras,
Longlisted plants are:
Binny Plants Nepeta ‘Joanna Reed’ bred by Joanna Reed.
Brighter Blooms Zantedeschia ‘Nashville’ bred by Sande BV.
Cayeux Iris Iris ‘Comme un Sourire’, Iris ‘Terre à Silex’and Iris ‘Moustache Rose’ bred by Richard Cayeux.
David Austin Roses Rosa ROALD DAHL (‘Ausowlish’) bred by David Austin Roses.
Hardy’s Cottage Garden Plants Gaura ‘Rosy Shimmer’s’ bred by Rosy Hardy, Cirsium rivulare FROSTED MAGIC (‘Lowcir’) bred by Lowaters, Geum ‘Scarlet Tempest’ bred by Elizabeth MacGregor, Hebe ‘Celebration’ bred by Stephen Humphreys and Nepeta × faassenii ‘Crystal Cloud’ bred by Sonia Wright.
Harkness Roses Rosa SWEET SYRIE (‘Harwilling’)and Roa MARY BERRY (‘Harupon’) both bred by Philip Harkness.
Harperley Hall Farm Nurseries Primula aurantiaca ‘Harperley Pink’ bred by Gary McDermott and Primula vialii ‘Alison Holland’ bred by John Holland.
Heucheraholics Heuchera ‘Magic Flute’, Heuchera ‘Hocus Pocus’, Heuchera ‘Silver Gilt’ all bred by Julie Burton.
Hillier Nurseries Acer shirasawanum MOONRISE (‘Munn 001’) bred by Carl Munn of Munn Nursery Oregon.
Hogarth Hostas Hosta ‘Smiling Mouse’ bred by Jan Van Den Top.
Millais Nurseries Rhododendron ‘Huisman’s Sun Star’ bred by Holger Hachmann, Rhododendron ‘Hachmann’s Orakel’, Rhododendron ‘Prinses Máxima’ both bred by Tijs Huisman.
National Chrysanthemum Society Chrysanthemum ‘Rossano Charlotte’ (Rossano Series) bred by Deliflor.
Peter Beales Roses Rosa SANDRINGHAM (‘Beamolly’) bred by Peter Beales Roses.
Philip Tivey & Sons Alstroemeria SUMMER PARTY (Tessumpar’) (Summer Paradise Series) bred by HilverdaKooji BV.
Plantagogo Heuchera 'Isabella' (Fox Series), Heuchera 'Madison Bride' (Fox Series) both bred by Richard and Vicky Fox.
Victorian Violas Viola ‘White Horses’ bred by Victorian Violas.
Birmingham City Councils’ Gerbera Garvinea ‘Sweet Memories’ bred by Florist Holland BV.
Cooks Garden Centre’s Photinia serratifolia PINK CRISPY (‘Oploo5’) bred by Alexander van Oploo
Dibley’s Streptocarpus 'Amy' bred by Lynne Dibley.
Double H Nurseries Phalaenopsis 'Sunny Smell' bred by Johannes and Christian Bremkens.
HY Hyde’s Lilium ‘Ying’ and ‘Yang’ (name to be confirmed) bred by Vletter Den Haan.
HW Hyde’s Lilium ROSELILY CHELSEA (name to be confirmed) bred by De Loof.
Hooksgreen Herbs’ Mentha × piperita f. citrata 'Variegated Grapefruit' bred by Hooksgreen Herbs.
Scotts’ Solanum tuberosum + Solanum melongena EGG AND CHIPS PLANT bred by Thompson & Morgan.
Scotts’ Fuchsia FUCHSIABERRY bred by T&M.
Sun Flower Square’s Calendula POWERDAISY SUNNY ('Kercalsun') (PowerDaisy Series) bred by Kerley & Co.
Sun Flower Square’s Lilium 'Perfect Joy' bred by Pinetops’ Stuart Paton.
Sun Flower Square’s Petunia NIGHTSKY ('Kleph15313') bred by Selecta One.
Sun Flower Square’s Solenostemon scutellarioides CAMPFIRE (‘Uf12823’) bred by Florida Foundation Seed Producers.
Sun Flower Square’s Tagetes patula 'Strawberry Blonde' bred by T&M.
Taylors Clematis’ Clematis chiisanensis AMBER ('WIT141205') bred by Stolwijk BV.