July plant of the month - lily

Trumpets and upturned petals herald the height of summer with spectacular colour and some with a heady scent

Lilium 'Corsage'In sun and shade, the colour and scent of lilies is one of the pleasures of this time of year. From pure white to deep red and purple, with yellows, oranges and pinks in between, Lilium are doing their thing at Wisley in July.

There are around 115 known species of these bulbous perennials, all with large prominent flowers although the individual species vary widely in their characteristics (and ease of cultivation), and can be as short as 30cm and as tall as 2m! The vast majority of commercially available garden lilies are hybrids, tending to be stronger, disease-resistant and with more and bigger flowers. And many of these are classified as either Oriental or Asiatic hybrids.

Oriental hybrids These have a strong fragrance with many flower types in pink, white or carmine. They prefer acid soil pH 6.5 or lower, so are often grown in containers of ericaceous compost rather than in the ground. They are hardy.
Asiatic hybrids These are generally unscented and their flowers tend to be smaller. They come in vivid colours including bright yellow, fiery orange, deep red and almost black. These are some of the easiest hybrids to grow, prefer soil pH 6.5 or above, and are very hardy.
Lilium 'Perfect Joy'This year, and next, we are trialling five of the seven groups in the 1949 RHS Lily Year Book classification. And that means that as well as the beauties around the garden, we have the most breath-taking show on the Trials Field. It’s simply stunning.
From a visitor’s point of view, the best thing about a trial is that you get the chance to see loads of different new cultivars side by side – easy to compare, and decide if you prefer one flower form or colour over another. They’re all named, too.
Lilium are not native to the British Isles. They come from temperate areas of the northern hemisphere including wooded habitats and scrub in Europe, Asia south to the Philippines, and North America.

How to grow lilies

To grow them, plant the bulbs in sun or partial shade, with 15cm of soil above them. A universal requirement is for well-draining soil, but plenty of water at appropriate times, never too dry or waterlogged. Feed regularly. The ideal planting time is in cool weather to let roots develop. They like being among shrubs with roots in shade flowers in the sun. Tall plants with heavy flower heads may need staking. After flowering, continue to water until the stems die down. Lilium bulbs are hardy and can be left undisturbed over winter.
It is important to check the soil pH needed by your variety: Asiatic hybrids generally require alkaline soil (although Longiflorum Asiatic hybrids tolerate any soil). Oriental hybrids need acidic soil. If your garden soil is not suitable, try them planted in containers. They make a glorious focal point in a patio pot!
Lily species are raised from seed. The hybrids are raised commercially by micropropagation, but you can propagate them yourself by dividing clumps of bulbs, or removing scales or bulbils. For more information contact or join the RHS Lily Group.

Lilium pumilumEnjoy the lilies blooming around Wisley, and see what you think of the trial. When it’s concluded in 2019, we will have an updated list of AGM varieties to try. The trial is focusing on interesting new Lilium cultivars (such as those from recent inter-section breeding trends), which challenge the previously-listed AGM cultivars. These new cultivars will be compared with a selection of species/cultivars grown as controls. The judges will be looking for floral appeal (colour, shape and fragrance), flowering length, stem strength and height, foliage quality, and disease resistance. We can’t wait for the results, but for now, we’re appreciating the flowers.


See also

RHS Plant Trials

Get growing: lilies

How to grow lilies in containers

RHS Lily Group

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.