Green roofs in the UK are becoming more and more interesting. Slowly but surely, green roof designers and installers are gaining experience in growing different plant species in these challenging conditions.

One of my all-time favourite green roof plants however is an old favourite. It’s a UK wild flower that blooms quite early in the year and copes will in a shallow growing medium. It looks delicate but is actually as tough as old boots. It’s Saxifraga granulata – the Meadow Saxifrage.

What does Meadow Saxifrage look like?

You probably won’t look twice at this plant unless it’s actually flowering. The leaves are roughly kidney shaped but they have jagged edges. They lay flat to the ground and for most of the year are pretty insignificant.

But the flowers – oh the flowers. They’re wonderful. Pure white, a centimetre or so wide and up to 12 on each branch. They’re held 15-20 cm above the ground (when growing in meadows etc they can be up to 50cm tall, but just like most plants, they tend to be more compact when growing on a green roof). Stems are sticky and hairy.

Each flower has 5 petals that form a kind of cup shape. The golden-yellow stamens sit prettily in the bottom of the cup.

Meadow Saxifrage

Image: Wikimedia Commons

When does Meadow Saxifrage bloom?

On a green roof made with Enviromat sedum matting, meadow saxifrage is the first species to come into flower in spring. Expect to see blooms from April – June. This is a perennial plant, so you should see it every year. And if it’s happy on your roof, it will reproduce so that the display gets better and better every year.

Why is Meadow Saxifrage such a good plant for green roofing?

The word “Saxifrage” means “stone breaking” and the plant family is named because these plants tend to grow in rock crevices on hills and mountains. You will probably have noticed Meadow Saxifrage’s cousins growing in rockeries or for sale in the alpine section of the garden centre.

These plants don’t mind harsh conditions. Neither do they mind having a very shallow layer of growing medium to root into. That makes them great for green roofs where a deep layer of substrate would put too heavy a load on the building.

The early flowering habit means that they bring spring colour to the roof and provide nectar and pollen for early flying bees.

Being a native wild flower, Meadow Saxifrage doesn’t need intensive feeding. On a living roof it manages well with one light feed a year. The fertiliser formulated for sedum roofs suits it perfectly.

Where can I buy Meadow Saxifrage?

This little plant is pre-seeded into Enviromat sedum mats. Depending on what time of year your Enviromat is delivered to you, you might not notice the plants to begin with. The leaves appear in early spring and disappear towards the end of summer. But rest assured, the plants are there.

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