Research Matters - New plants for green roofs

Green roofs provide an eco-friendly way of cooling buildings but the roof environment is a tough one for plants. While succulents such as Sedum spp. seem well-suited to it, a roof consisting only of sedums can present a rather bland appearance.

In the experiments reported here, species that naturally grow in shallow, well-drained soils were grown in "dry-down" trials together with sedums and other succulents. The plants were raised singly in containers with a 100mm depth of substrate and were grown for 10 weeks in a greenhouse with irrigation.

The interval between successive irrigations was then gradually increased until eventually no more water was given. Each species was then left without water until no viable green tissue could be seen above ground. At this point, irrigation was restarted and the proportion of plants of that species that revived was recorded.

In general, succulent plants were better able to resist being dried down and were also more likely to recover again. The succulent plants Sempervivum 'Royal Ruby', Sedum lanceolatum and Allium cernuum proved to be ideal for green roofs.

Among the herbaceous plants tested, Antennaria parvifolia, Buchloe dactyloides and Thymus pseudolanuginosus survived for a reasonable time without water and the latter species was thought particularly suited for green roof use.

Dr Ken Cockshull, Associate Fellow, Warwick Crop Centre, University of Warwick

Moisture Content of Extensive Green Roof Substrate and Growth Response of 15 Temperate Plant Species During Dry Down by Bousselot, Klett and Koski (2011). HortScience 46 (3): 518-522.

ISHS members can view HortScience from the website www.ishs.org


Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Sign up now
Already registered?
Sign in

Before commenting please read our rules for commenting on articles.

If you see a comment you find offensive, you can flag it as inappropriate. In the top right-hand corner of an individual comment, you will see 'flag as inappropriate'. Clicking this prompts us to review the comment. For further information see our rules for commenting on articles.

comments powered by Disqus

Read These Next

Tree planting guide - three basic rules

Tree planting guide - three basic rules

Choosing the right plant, correct planting procedure and best aftercare are the three basic rules for sucessful tree planting, Sally Drury explains.

Tree planting - what are the benefits of planting trees?

Tree planting - what are the benefits of planting trees?

Mitigating climate change, providing windbreaks and reducing the risk of soil erosion are some of the best reasons for planting trees, says Sally Drury.

Dierama

Dierama

Beautiful but underused, this tall and elegant plant can persist for years, says Miranda Kimberley.


 
Horticulture Jobs
More Horticulture Jobs

Industry Data

An exclusive report for HW subscribers revealing the key development trends, clients and locations for 2017.

Are you a landscape supplier?

Horticulture Week Landscape Project Leads

If so, you should be receiving our new service for Horticulture Week subscribers delivering landscape project leads from live, approved, planning applications across the UK.

Landscape Contracts & Tenders

Products & Kit Resources

BALI National Landscape Awards 2016

Read all about the winning projects in the awards, run in association with Horticulture Week.

Noel Farrer

Founding partner of Farrer Huxley Associates Noel Farrer on landscape and green space
 

Read Noel Farrer