Horticulture Magazine

Sedum ‘Stonecrop’

purple ornamental sedum in the garden
By CHRIS LEE
Chris Lee, MA - Gardening Writer

Chris is a gardening writer and nature enthusiast. He graduated from Oxford Brookes University in 2022 with an MA in Psychology. Chris works with the Leeds Green Action Society, helping their food cooperative by growing various fruit and vegetables on their two allotments in Hyde Park, Leeds.

/ Updated August 24th, 2023
Reviewed By COLIN SKELLY

Colin is a Horticulturist and Horticultural Consultant with experience in a range of practical and managerial roles across heritage, commercial and public horticulture. He holds the Royal Horticultural Society’s Master of Horticulture award and has a particular interest in horticultural ecology and naturalistic planting for habitat and climate resilience.

/ Meets Our Editorial Guidelines
Contributions From RAY STEPHENSON
Ray Stephenson, Chairman of The Sedum Society

Currently the Editor and Chairman of The Sedum Society, Ray has written over 200 papers on sedums and also published his own book all about this prized succulent. He also has his own national sedum collection that is recognised by Plant Heritage.

, NIAMH MULLALLY
Niamh Mullally, Owner of Southwold Succulent Co.

With over 20 years of experience in horticulture, Niamh is the owner of Southwold Succulent Co, based in Suffolk, UK. Niamh has a large following on Instagram, where she shares other plants that she grows in her garden, as well as the succulents she is so fond of.

, KATHERINE CROUCH
Katherine Crouch - Garden Designer

Katherine Crouch is an award-winning Garden Designer who won the BBC Gardener of the Decade in 2008. Other accolades include a Gold Medal at the RHS Chelsea Flower Show in 2013 and BBC Gardener of the Year in 1999. Katherine still runs her garden design service and also offers talks and consultations at various gardening clubs, online and in person.

Sedum – or stonecrop – is a popular succulent.

They’re resistant to heat, drought, and other harsh conditions, making them great plants for beginners.

One of the reasons this plant is so popular is its enormous versatility in appearance.

Some varieties sport jelly-bean-like buds, while others have hugely flamboyant yellow flowers which seem to paint sunshine right across your garden.

“Sedum is a large genus with a huge variety of species that include types for succulent collectors through to hugely popular garden favourites,” shares Master Horticulturist Colin Skelly.

“As a garden perennial, they are tough, drought tolerant when established and provide beautiful late summer flowers.”

For this guide, we’ve worked with some of the most experienced sedum growers in the UK:

  • Ray Stephenson – Editor and Chairman of The Sedum Society.
  • Niamh Mullally – Owner of Southwold Succulent Co.

“The palette of colours, especially on the evergreen varieties, makes me particularly passionate about growing sedums,” says Niamh.

“Once established, maintenance is minimal, and they have a great capacity to thrive in droughts and survive harsh winter conditions.”

Overview

Botanical NameSedum
Plant TypeSucculent
Native AreaMostly northern hemisphere; Africa and South America
Hardiness RatingVarious
FoliageSucculent leaves and stems
FlowersVarious
When To SowApril, May
Flowering MonthsJune, July, August, September, October
Sunlight

Preferred
Full Sun

Exposure
Exposed or Sheltered

Size

Height
0.5 – 1M

Spread
0.1 – 0.5M

Bloom Time
Varies

Soil

Preferred
Chalk, Loam, Sand

Moisture
Well drained

pH
Neutral / Alkaline

Although the sedum genus also includes annual and biennial plants, the majority of popular varieties are perennial. 

Before choosing your Sedum variety, bear in mind the wide range of potential aesthetics.

Variety of multicoloured sedum in rock garden

Researching the varieties available, and understanding what each will look like throughout its lifetime, is a key part of choosing the right Stonecrop for your garden.

This is especially true if you’re planning to create a succulent display or rock garden, something along the lines of the image above.

Whatever variety you choose, you can expect carpets of colour from yellows and oranges, to reds and pinks – and even turquoises, blues and greys.

How To Grow Sedum

Sedum doesn’t grow as large as some other plants.

The maximum height for the varieties above is about 0.5m, although many will be smaller.

People enjoy Stonecrops for their mat-forming tendencies – giving you low, wide spreads of colour and visual interest.

“Grow Sedums in your garden for a drought-proof, bug-proof, windproof, hardy, late-summer spectacular in full sun on average soil,” says Katherine Crouch, an award-winning garden designer.

“Neither fussy nor invasive, you can split your sedum every three years and it won’t splay.”

If after reading this far you’ve decided to introduce a Sedum to your garden, here’s what you need to know.

Hardiness

Each of the varieties above has a hardiness rating of H5 or higher, meaning they can survive down to -10°C – or pretty much everything a British winter can throw at them.

evergreen orpine covered in snow in a winter garden

Several varieties are rated H6 or H7, meaning they’ll still manage down to below -20°C. 

Soil Requirements

“I recommend John Innes no 3,” says Niamh.

“When combined with perlite, it’s sufficiently free-draining whilst being a permanent planting medium.”

All the varieties above will do just fine in sand or loam, with others being happy in chalk or clay as well.

They’re generally not fussy about pH, with most varieties accepting alkaline or neutral soil.

white flowering wild stonecrop growing in a mulched border

A couple can manage acidic, too – best to check the specific needs of the variety you choose.

The most important thing when planting a Sedum is the moisture level.

“Concentrate on your soil mix. Never use multi-purpose compost and make sure it’s free draining before you plant,” warns Niamh.

Your soil should be well-drained, but this isn’t a plant that will grow well in waterlogged or even overly moist soils.

Planting

Most Stonecrop varieties require full sunlight to thrive, although a few can make do in partial shade.

All of those above will grow well while facing south, but beyond that, there’s no hard-and-fast rule for which direction your Stonecrop should face.

Some in our list are quite versatile, being able to cope with three or even four directions.

Others are fussier, and will only grow their best in a south-facing aspect.

Our advice is to look at specific information for the variety of Stonecrop you’re planning to plant.

When To Plant

The best time to plant a Stonecrop is spring, after the risk of frost has passed and before summer starts to heat up.

gardener using a blue trowel to plant out a Sedum telephium plant

Make sure to plant out in the correct soil conditions, as newly-planted Stonecrops will be most liable to damage.

Planting Out

When planting from seed, leave at least 15cm of space between each plant.

Also make sure to read up on your variety, because certain ones need more space – sometimes up to 60cm.

If you’re growing from a division taken from another Sedum plant, ensure the whole root ball is covered by soil.

The hole should be deep enough that the entire root ball is buried just below the surface.

Cuttings are even more straightforward: just place the cutting in the hole and cover it over.

If soil conditions are correct, then your plant should take root easily.

Sedum Care

Newly planted Stonecrop plants need a bit of TLC to become properly established.

Keep a careful eye on the soil moisture levels, making equally sure that they don’t stay too wet or get too dry. 

Once your plant is established, you don’t need to be quite so vigilant about moisture levels.

stonecrop plant surrounded by a metal frame used to support new growth

Sedums are succulents, after all: a type of plant noted for its ability to weather drought and retain water for dry spells.

Sedums will appreciate a layer of compost being added to the soil once a year.

Avoid anything too high in nitrogen, as this can cause wilting.

If you’re growing your sedums in a container, Niamh has the following advice:

“In Suffolk, I use 40% soil to 60% perlite for my growing medium. This ratio can be increased to 20/80 if you’re in a wetter area.

“Keep a bag of horticultural grit in your shed or greenhouse. The grit level may drop after a harsh winter and a top-up in springtime will revive your containers.”

Pruning

Stonecrops can be safely pruned back to keep them from getting unruly. 

If you’re planning to prune, deadhead after flowering.

There’s no need to do this, however, and the choice is purely aesthetic.

Some gardeners prefer to leave the fading flowers to add a bit of extra colour.

Common Problems

Stonecrops are relatively well-behaved when it comes to pests.

However, Ray explains that the problems that might face sedums vary massively depending on the variety.

“Some varieties need specialised horticulture, whilst others are difficult to kill. You need to know the requirements of the one you are growing.”

Take the usual garden precautions, and you should be able to avoid spending your whole life battling pests and infestations.

As we’ve said throughout this guide: your best bet is to look at specifics for the type(s) you’ll be planting in your garden.

Some are renowned for being pest-free, while others have slightly higher tendencies of attracting certain critters.

magnified view of caterpillar sat on the pink flowers of a stonecrop plant

Knowing which precautions you should take can help you to avoid problems before they arise.

Here’s what to look out for:

Glasshouse Whitefly

This is a sap-feeding insect that likes to suck the life-giving nectar out of all sorts of plants. Sadly, certain varieties of Stonecrop are on their preferred menu.

Sometimes you’ll see the insects themselves – small, with white wings. Other times you may notice their calling card – sticky residue on your plants.

Once whiteflies establish themselves, they can be hard to remove. Deliberately introducing small wasps is one way to control this pest (you can order them online). Alternatively, certain organic sprays can bring them under control.

The best way to avoid whiteflies is to keep on top of weeding, and checking bought plants for any signs of infestation before planting them out.

Aphids 

These fellas also like to suck sap, and are also attracted to certain varieties of Stonecrop.

As with whiteflies, you’ll usually be able to see aphids with the naked eye – they’re small and green, and hang around on the leaves of plants they’re feasting on.

If your Stonecrop looks weak or generally unhealthy and you can’t see any aphids, take a closer look – sometimes they lurk out of sight.

leaves of sedum reflexum covered in tiny black aphids

Small amounts of aphids can be tolerated, but if they start to get out of control, certain pesticides can be used to remove them.

The health of your plant is the benchmark of whether an infestation is getting out of control.

Glasshouse Red Spider Mite

Yet another bug that will help itself to the sap from your Stonecrop’s leaves, the glasshouse red spider mite is worth keeping an eye out for.

The symptoms will be similar to previous pests in this list: an unhealthy plant with stunted growth, with a possibly mottled appearance.

This mite thrives in warm conditions, so an outdoor plant will probably be safe in winter.

If your Sedum is growing in a greenhouse, keep a lookout all year round.

Removing infected plants immediately is a good way to prevent further spread; otherwise, predatory mites and certain types of pesticides offer effective control.

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