Herbaceous

Sedums

(Hylotelephiums)

for the perennial garden

Gorgeous, fleshy, colourful succulents: the large garden sedums are indispensable, trouble-free late-flowering perennials, loved by pollinators. Here I share the best performers from my garden.

Introduction

Herbaceous Sedums

Garden-worthy sedums come from an extensive group of drought-tolerant succulents which are part of the stonecrop (crassula) family.

Many of the true sedums are tiny alpine plants, primarily suited to growing in alpine troughs, gravel beds or on sedum roofs.

In this article, however, I am looking at the larger, herbaceous sedums that can hold their own in the perennial border.

Confusingly, most of these herbaceous sedums have recently been moved from the genus Sedum to Hylotelephium, but for simplicity, I will refer to them as Sedums throughout this article. Most nurseries now use Hylotelephium on their labels.

Border sedums are versatile deciduous perennials, which come in two main size categories: the larger, upright varieties reach 1.5 – 2ft (45-60cm) tall and have thick stems, while the smaller, trailing varieties tend to spread outwards more, while only reaching 6 – 12in (15-30cm) high.

Origins of Garden Sedums

Most of the large upright sedums are hybrids or variants of two wild species.

Native to Eurasia (including the UK), is Orpine (Sedum telephium) — pictured here — which has fleshy toothed leaves alternating along the stems, and tall flower-heads, often described as broccoli-like.

The other wild species is the Ice plant (Sedum spectabile) — native to China and Korea — which has leaves in opposite pairs, and larger, flatter heads of pink flowers.

Both wild species show considerable variation in size, leaf and flower colour, which is further elaborated through hybridisation leading to the availability of many named cultivars.

This provides the gardener with many options including a variety of flower colours in shades of pink, red, yellow, green and white. The stems and foliage of sedums come in many succulent colours too: purple, reddish-yellow-green and glaucous blue-greens as well as variegated forms.

The native orpine — Sedum telephium,
syn. Hylotelephium telephium
[William Curtis Flora Londinensis Botanical Prints 1775]

Origins of Garden Sedums

Most of the large garden sedums are hybrids and variants of these two wild species.

Native to the UK is Orpine (Sedum telephium) — pictured here — which has fleshy toothed leaves alternating along the stems, and tall flower-heads, often described as broccoli-like.

The other wild species is the Ice plant (Sedum spectabile) — native to China and Korea — which has leaves in opposite pairs, and larger, flatter heads of pink flowers.

Both species show considerable variation in size, leaf and flower colour, in the wild, which has been further elaborated through hybridisation and cultivation, leading to the availability of many named cultivars.

This provides the gardener with many options including a variety of flower colours in shades of pink, red, yellow, green and white. The stems and foliage of sedums come in many succulent colours too: purple, reddish-yellow-green and glaucous blue-greens as well as variegated forms.

LARGE / UPRIGHT
40-90 cm | 16-36 in

Sedum spectabile ‘Brilliant’
(pale-pink; 70x110cm)
Sedum spectabile ‘Hot Stuff’
(pink; 40x40cm)
S. telephium ‘Purple Emperor’
(purple/pink 60×100 cm)
S. ‘Matrona’
(purple/light-pink; 100x120cm)

SMALL / TRAILING
15-40 cm | 6-16 in

SedumVera Jameson’
(20x80cm)
S. SunSparkler Series
(various; 20x30cm)
S. ‘Ruby glow’
(dark purple/pink; 30x80cm)
Sedum sieboldii Variegatum
(blue-yellow/pink; 20x40cm)

MAT / GROUND COVER
5-15 cm | 2-6 in

Sedum cauticola
(glaucous/pink; 15cm x 75cm)
S.
‘Bertram Anderson’
(purple/pink; 12x100cm)
S. spurium
cultivars
(various/pink; 15x50cm)
Sedum reflex
(Silver-grey/yellow; 20x60cm)


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Large

upright

BORDER SEDUMS

Sedum spectabile ‘Brilliant’ (September)

LARGE SEDUMS

Flower and foliage colour
Border sedums come in every possible shade of pink: from reddish to purplish, with brighter candy-pinks in the middle. However, green, white and pale-yellow flowered varieties exist. The succulent leaf and stem colour is a big part of the appeal, coming in greens, blues, purples and bronzes. Subtle variations in leaf shape, texture and growth patterns add to the diversity of cultivars.

Growth
Sedums grow from a dense crown of tightly packed buds, typically producing a shuttle-cock shaped clump of stems topped with wide flower heads. Generally, they form 2ft x 2ft (60x60cm) clumps, however, larger varieties can reach 3ft x 4ft. In my experience site, soil and light can affect final size which makes planning a bit tricky.

Season of interest

Spring: buds emerge from a dense crown, creating an interesting textured dome of coloured succulent foliage.
Summer: expanding clumps of colourful succulent stems, topped with intricately branched flower heads — fascinating even before the flowers open.
Late Summer: flowers open and immediately become a magnet for pollinators. Flowers typically fade to brown; some more gracefully than others.
Autumn: The foliage and stems of some varieties take on interesting autumnal hues before turning brown.
Winter, their dried stems and seed heads an be quite sculptural and have been used effectively in winter garden alongside silver birches and red-stemmed dogwoods.

The Chelsea Chop
Most sedums need no staking, but the largest, top-heavy varieties (such as S. spectabile ‘Brilliant’) can flop as the clumps get bigger. Fortunately, they respond to the ‘Chelsea Chop’ — cutting back all the stems by 3-6 inches in May. Following this the stems produce side shoots, carrying several slightly smaller flower-heads. The overall growth is reduced, so stems are less likely to flop.

Support
An alternative to the Chelsea chop, is to grow the largest sedums through the wire frame of a large upturned hanging basket.

Dividing Clumps
Once established, large clumps are easy to divide. Simply dig them up in spring, and chop the crown into several large sections. Replant them ensuring they don’t dry out in the first year. Excess divisions can be potted up using a well drained loam and grown on.

Three classic Large sedums

Sedum spectabile ‘Brilliant’
Beautiful at every stage with glaucous-green leaves and large flat heads of bright pink flowers in September. Grows into a large clump. Stems can flop, so are best given the Chelsea chop in late May, or grow it through an upturned hanging basket for support.

Sedum ‘Matrona’
More upright and with sturdy rhubarb-coloured stems, which rarely need staking. The foliage is a dark reddish-green. In summer the broccoli-shaped flower heads carry broad heads of pale pink starry flowers loved by bees.

Sedum ‘Autumn Joy’
Similar to ‘Brilliant’ but with darker pink flowers turning to brick-red, and with darker green foliage. Flowers from late August into October. Unfortunately, its flowers are sterile, so it does not appeal to pollinators. (The leaves in the photo above are nearby Agapanthus)

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Large Upright Border Sedums

Strawberries
& cream

Sedum ‘Strawberries and Cream’ is one of the more compact large sedums which over time grows into a clump 50cm wide and tall. In May and June, the foliage and stems take on an unusual bronze-red colour. The flowers open a beautiful mix of yellow and pink in late July.

Unfortunately, the blossoms are over in just a few short weeks, but during that time Bees will visit incessantly. The biggest downside is how quickly the flower-heads turn brown – a sight we expect only later in the summer. If you find them unsightly, just dead-head, but if you can put up with them until the autumn they will become an asset.

I grow Strawberries and Cream in a raised bed with other drought tolerant plants which provide a long season of interest. Below: white flowers of garlic chives (Allium tuberosum), the blue fairy thimble bell flower (Campanula cochlearifolia ‘Elizabeth Oliver’) and mauve Society garlic (Tulbaghia violacea), pink hyssop (Hyssopus officinalis ‘Pink form’) and late-flowering pink German garlic (Allium senescens glaucum)

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Small Trailing Border Sedums

Small, trailing

Border Sedums

The small border sedums are like miniature versions of the large border sedums but with thin, lax stems. Like their larger cousins, they produce starry flowers in the late summer (Aug-Sep) which are highly attractive to pollinators. The main difference is that they are shorter, typically only reaching 1ft (30cm) tall, but spreading to 2ft (60cm) or more. Some, such as ‘Vera Jameson’ form long trailing stems, such that their flowers tend to be produced around the edge of the plant with the centre somewhat bare. The trailing habit can be put to good use, as stems will weave through adjacent plants without harming them. Others, such as the SunSparkler® Series, make denser clumps with a smaller spread, so stems remain more upright in the centre of the mound and flowers cover the plant all over.

Many of the small border sedums change colour throughout the season. Above is Sedum ‘Vera Jameson’ early in April. The foliage is distinctly glaucous blue, with a hint of dusky purple in the stems. By July, however, the same plant has spread to over 3ft (90cm) across with the stems and flower heads taking on a strong Burgundy red. (Seen here growing charmingly with white gypsophila and the diminutive pale-blue Campanula ‘Elizabeth Oliver’)

Sedum ‘Plum Dazzled’

A wonderful small sedum, with deep purple foliage all season. The flowers open in August and September – a good deep pink. Growing here with glaucous-blue myrtle spurge (Euphorbia myrsinites) and Russian Sage (Perovskia ‘Little spire’) — h20cm s40cm.

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Mat-Forming, Alpine Sedums

mat-forming

ALPINE

Sedums

One of the most reliable ground cover sedums is the crimson stonecrop (Sedum spurium). This low growing, mat-forming alpine is tough enough to form a carpeting plant at the front of the border or in a gravel or rock garden and even tolerates some shade.

There are many named cultivars of crimson stonecrop, including white, pink, red and yellow-flowered forms. The foliage consists of small serrated succulent leaves in whorls along trailing stems. Most cultivars have dark green leaves, but red, purple, variegated and golden leaved forms can be found.

Given an open, bright position, crimson stonecrop will create a dense mat, just 4in (10cm) thick and up to 2ft (60cm) across. Like most sedums it is drought tolerant and thrives on poor soil in a sunny or part-sunny spot.

Sedum spurium ‘Spot on rose’ has incredible pink cactus-like blooms. The one above is growing happily in the shade of a small deciduous shrub (Vitex agnus-castus)

Sedum spurium ‘ Dragon’s blood’ is grown primarily for its deep red foliage. Here, it is being prettily invaded by two varieties of creeping thyme, which will gradually overtake it and kill it.

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Growing Sedums


 

SEDUMS GROWN IN THE BORDER: Large and small sedums can be grown effectively in garden borders, where they provide a long season of interest. There are actually 6 different sedums in the photo above!

GROWING SEDUMS

Sedums are easy to grow being generally trouble-free and long lived. They prefer a failrly free-draining and not-too-fertile soil in full or part-sun. Avoid excessively rich or waterlogged soils.

Growth pattern
Sedums grow from a crown of densely packed buds. As the stems grow they spread outwards, forming a shuttlecock shape. Many of the smaller varieties have long thin stems, which trail across the ground, leaving the centre of the plant open with flowers around the edge. These wandering stems can snake effectively through adjacent plants.

Planting position
The taller varieties do well in the middle of the border, planted singly or in groups of three or more. The smaller varieties need to be placed to the front of the border where they look good against gravel, rocks or low ground-cover plants. Some of the lower-growing varieties will trail over the edge of low walls or raised beds.

Self Seeding
Sedums often self-seed with the offspring showing a high degree of variation. I like potting these up and seeing how they develop: often, unfortunately, their flower colour tends to be less distinct than the parent.

Propagation
Sedums are relatively easy to propagate.
(1) Division: Clumps can easily be dug up, divided with a sharp spade, and replanted.
(2) Offsets: Sedum stems readily produce roots and shoots close to the soil. If you spot a stem that is sprouting buds close to the soil, simply cut back the main stem somewhat, then remove the remaining section with the basal buds using a trowel to retain any soil the stem has rooted into. Pot it up using a free draining soil.
(3) Cuttings: simply cut a stem in summer, remove the lower leaves and place it in a jar of water, until roots sprout. Pot the cuttings up and grow on.

SEDUM PROBLEMS

Slugs and Snails
Although usually pest free, watch out for slugs and snails attacking the crowns in winter and early spring. Keeping the winter crown free of leaves and mulch can help.

Reversion
One problem with some of the named varieties is reversion, where a desired trait such as variegation, decorative leaf or flower colour spontaneously reverts to the typical form. This can affect part or all of a plant, and is especially problematic when plants are propagated. Consequently, named varieties can vary considerably between nurseries, making accurate identification difficult. If you want more of a particular variety, it is often best to divide your own plants rather than buy new ones, which may look quite different.

Root rot
If your soil or pots are too moist, the roots of sedums will rot. Often, the plant will soldier on, and appear to be alive, even producing new buds and shoots from the base in spring. Give the old stems a slight tug, though, and it will come away in your hand. If the soil dries out, new roots will grow, but the plant will suffer a set back and take a few years to recover.

Vine Weevil
Sometimes vine weevil grubs attack the roots of sedums grown in pots. The symptoms are similar to root rot, with the plant gradually deteriorating, and eventually coming away from the soil. For chemical control try Bug Clear Ultra Vine Weevil Killer. Alternatively use a biological control such as Nemasys® Vine Weevil Killer.


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Growing Sedums in Pots

Growing

SEDUMS

in pots

  1. Sedum spectabile — as part of a group of pots with Agapanthus and white roses
  2. Random seedling — found and potted up. Grown on in greenhouse with other succulents.
  3. Sedum ‘Matrona’ — growing happily in terracotta pot.
  4. Sedum ‘Double Martini’ — planted with other succulents in terracotta planter.
  5. Sedum ‘Strawberries and Cream’ — rescued self-sown seedling
  6. S. spectabile cuttings — cut stems rooted in water then transplanted into pots.


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Planting Ideas

Planting

Ideas

COMBINING SEDUMS WITH SILVER FOLIAGE This unidentified pink sedum is one of my favourites, growing into a neat dome just 40cm high. It has rounded grey-green leaves and soft pink buds. I have combined it here with silver foliage including the fluffy mugwort Artemisia schmidtiana ‘nana’ and the fine pointed foliage of Snow in Summer, Cerastium tomentosum.

SEDUMS IN A COASTAL PLANTING Sedum spectabile ‘Brilliant’ is planted here with other perennials that tolerate coastal conditions: salt-laden winds and full sun. Top left is the lilac daisy Erigeron glauca ‘Sea breeze’, while in front is the hardy ice plant, Delosperma cooperi. Agapanthus, Echinops and Eryngium would also be work as companions.

DROUGHT-TOLERANT PERENNIALS In this part of my garden, the purple foliage of Sedum ‘Plum Dazzled’ works perfectly with other dry-garden perennials, including Alliums, blue and white Triteleia ‘Rudy’ (bottom left), vivid blue Salvia ‘May Night’ (top left), and the glaucous-blue foliage of Perovskia ‘Little Spire’ (top right) and Euphorbia myrsinites (bottom).

△▽ SEDUMS IN A GRAVEL GARDEN Sedums of all sizes are at home in gravel and rock gardens.

Above, Sedum ‘Plum dazzled’ is growing with (clockwise): Allium senescens subsp. glaucum, Helianthemum ‘Wisley pink’ and Salvia ‘Snow Hill’.

Below, A spontaneous seedling of Sedum ‘Strawberries and Cream’ is growing with cobweb house leeks (Sempervivum arachnoideum) and a patch of biting stonecrop (Sedum acre).

SEDUM ROOF The small alpine sedums will cope well with the harsh conditions on a green roof, growing in minimal substrate with little water. This photo is from my green roof garden a few years ago. In the foreground, red leaved Sedum spurium ‘Dragon’s blood’ and silver-blue Sedum reflexum fight it out. The orange plant in the distance, is Sedum ‘Angelina’ poking up through a carpet of wooly thyme. The plant in the middle of the photo, covered in strange seeds, is Euphorbia myrsinites.

SEDUM GROWING ON THE EDGE OF A POND
This trailing Sedum ‘Vera Jameson’ comes into flower at a time when many of the other perennials have finished, including the cranesbill (Geranium sanguinium) behind it, and the nearby spearmint (left) and red valerian (right).


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Additional Resources


3 thoughts on “Herbaceous Sedums In The Perennial Garden”

  1. I have a Sedum Spectabile and while I was chopping off last year’s stems, I noticed that a couple of the bigger stems had tiny plantlets growing on it. Is this usual and how do I grow them on?

    Reply
    • Hi Georgie! Yes, this is one of the ways they reproduce. You can cut off the stem above and below these plantletts – preferably just below ground to get some roots too, but this isn’t essential. Plant the section of stem shallowly (even horizontally) with the baby sprouts just above the surface, in a sharp-draining compost, and they will grow roots. Or you can just leave them in situ, cutting off the old stem above them, and your clump will expand.

      Reply

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