Light up the land

This group of plants come in a range of vibrant colours from pink, peach, orange and yellow to purple and white. Flowering stems can reach impressive heights ranging from 30cm to 120cm. These plants are semi evergreen herbaceous perennials, producing rosettes of pale green leaves from which the tall flower stems erupt.

Originating from the Himalayas and Western China, candelabra primulas are happiest in damp or wet conditions, ideally suited to being planted in bog gardens, pond edges or stream banks. They have a long flowering season across the range of types extending from late April to the end of July.

There are approximately twenty species of candelabra primula. Here at RHS Garden Harlow Carr, some of the most notable include:

Primula chungensis: originating from the mountains of south-west Sichuan in China, this species prefers semi shade to full sun. This plant has a short flowering stalk of up to 40cm with abundant terracotta coloured tubular flowers held in whorls above mid green scalloped rosettes of foliage. The orange flower tube is scarlet in bud but orange red in full flower, giving a pleasant two-tone effect.

Primula japonica ‘Harlow Car’ hybrids: a group which are heavily hybridised, they originate from the Northern Horticultural Society days before Harlow Carr merged with the RHS. Then, primulas were grown along the streamside in distinct species groups: blocks of orange P. bulleyana growing in close proximity to blocks of mauve P. beesianum, red P. Japonica and purple P. pulverulenta. Over time, these closely related species cross bred and intermixed, forming the much-loved Harlow Car (sic) hybrid primulas we know today.

Seed of this newly-recognised primula japonica ‘Harlow Car’ hybrid was first made available in the early 1960s. Eagle-eyed readers may notice that the spelling of Harlow Car hybrids has only a single ‘r’; this was a mistake made when they were first named and has stuck ever since.

Today RHS Harlow Carr propagates 500 ‘Harlow Car’ primula seedlings every year. Each batch of hybrids differ in colour composition, some predominantly pink, some more yellow or orange. Rarer colours such as white and purple are favoured, and the seed of these more unusual coloured plants are painstakingly collected, sown and grown on. The ideal is to have an equal number of all colours in a Harlow Car hybrid primula mix.

The primula Japonica ‘Harlow Car’ hybrids can be found planted in large groups along the iconic streamside, alongside blue poppies, ferns and other bog-loving plants and in large groups in the woodland.

Primula florindae: also known as the Tibetian cowslip or giant cowslip, this long-stalked candelabra primula has flowering stems that reach 1.2m in height. Its stout stems carry large terminal umbels of nodding, fragrant, bright yellow flowers, white-mealy within. This primula – which is native to South East Tibet and will not tolerate dry soils - is planted extensively in large groups along the streamside.

Primula Japonica 'Apple Blossom': this AGM variety is a popular Japanese candelabra primula. 'Apple Blossom' is a deciduous perennial with pale green, wrinkled, egg-shaped leaves. In late spring and early summer, 2-6 tiered whorls of flowers are borne on stems about 45cm tall. The pale pink flowers have a darker reddish-pink centre.

Primula Japonica 'Miller's Crimson' AGM: has attractive tiers of deep reddish-purple flowers which appear on stout, upright stems in late spring and early summer. A striking candelabra primula, it will thrive in the dappled shade of a woodland garden where there is reliable moisture.

If you are growing these plants at home, cultivation tips include:

· Grow in open ground only and never in pots.

· They do best in a sheltered sunny position or in partial shade.

· They can only be grown in a sunny position if the soil is consistently moist, but not waterlogged.

· The soil must be deep, moisture retentive and nutritious. Application of well-rotted manure or mulch should achieve this.

· Some species such as P. bulleyana, prolifera, secundiflora, poissonii, wilsonii will tolerate prolonged waterlogging, whereas others such as P. Japonica, pulverulenta, chungensis, cockburniana will resent it.

These plants are semi evergreen, so do not panic if leaves die back over the winter period; they will re-leaf in spring. They are a low maintenance plant and easy to grow, providing they are placed in the correct position. Over time, they will form large groups and can easily be propagated by division.

The majority of candelabra primulas freely hybridise or cross, so if you’re planting different species together, try removing old flower heads or selecting the plants you prefer.

Jobs for the week

· Lawn maintenance, application of selective weed killers

· Staking herbaceous perennials

· Planting up summer bedding displays

· Seed sowing and planting out tender vegetables

With thanks to Matthew Brewer, Horticulturist at RHS Garden Harlow Carr

DIARY DATES

Until 30 June: The ‘Language of Flowers’ exhibition The Victorians believed that every flower - and some vegetables - carried a symbolic meaning: a hellebore for scandal, a rose for love. Learn about the symbolic meaning of flowers at an exhibition taking place at Harlow Carr’s library. Normal garden admission applies.

23-25 June: RHS Garden Harlow Carr Flower Show Browse, buy, and pick up advice from more than 40 specialist nurseries and garden trade stands at Harlow Carr’s second annual flower show. Visitors can enjoy a full programme of talks and demonstrations then escape the crowds with a relaxing stroll in the stunning surroundings of the garden: don’t miss the summer Streamside spectacle of Harlow Carr’s famous dolly-mixture candelabra primulas. Entrance is included in normal garden entry and the show is open from 10am – 5pm each day. Visit www.rhs.org/harlowcarr for full details including parking.