Plants

Vegetation For Roofs

There are multiple ways and many types of plants that can be used for green roofs.  The elements that go into determining which will work best depend on a number of factors:

  • Climate Conditions–sun exposure; precipitation; etc.
  • How do you plan to use space–amenity; cooling; living classroom; storm water management; vegetable garden

The varieties of plants for successful extensive green roof system plantings depend on exposure to sun.  Hardy sedum perennials are generally chosen for use on Extensive Green Roof Systems because they are drought tolerant and shallow rooting.  They generally thrive in full sun exposure even when the sun is low on the horizon in early April and late October.  These are the prime growing seasons for sedum varieties and poor placement on roofs with shadowed cover will curtail their spreading habits resulting in sparse vegetated cover.  We have adapted a palette for roofs with less than optimal cover. If your roof environment is partly shaded, we would suggest Bio Diver City Mix B. If sun exposure each day is:

  • 75% to 100%  = Bio diver City Mix A
  • 50% to 75% = Bio diver City Mix B

If below 50% sun, can represent a challenging environment for Extensive plantings.   Please call us for a consult: 866.675.9963.

Seed

Seed is available for augmenting the coverage of certain installations when the cost for immediate vegetated cover is beyond budget.  Sedum will mature from seed in two to three years.  Ideally suited to Eco-Roof Systems.

It is recommended that your installer be experienced in hydro seeding or using sedum seed, as they are very small and coverage rates very with weather  and mulching conditions.

Cuttings

One way to plant a green roof, living roof or vegetated roof is to spread ‘cuttings’ of the hardy sedum perennials that are most suited to growing in the environment.  Cuttings are small clippings of sedums sold by the pound.  Sedum cuttings will survive for many days in cool moist environments without  media in certain seasons.  When spread on newly laid green roof media, they begin to root on their own and will soon establish where they are placed.  This can be an economical way to plant or improve the cover on an existing green roof.

Vegetated Mat

Green roofing is a common practice in northern Europe.  In the areas of Germany, Switzerland and the Netherlands, 90% of all green roof installations are covered with vegetated mat. This method allows the installer to place a pre-grown mat, similar to sod for your lawn, over the drainage and media system and achieve immediate cover of up to 90% on installation.  See the case study for the Fed Ex Cargo Facility at O’Hare airport.  This method is now commercially much more economical than any other type of green roofing for a large roof structure over 10,000sq ft.  In parts of northern Europe, this vegetation is even used to landscape highways and by-ways because of its environmental success and cost.

In bloom

Green Roof Solutions works directly with all providers of this type of vegetation and can provide optimal pricing due to our buying power.  Plant species are pre-selected for your growing zone.  We have access to over 30 acres of mat inventory at any time and can combine shipments to lower your cost.

We can arrange delivery to your green roof project by refrigerated truck.  It is recommended that installation be timed immediately upon delivery.

Please contact us if you need some help making decisions on vegetation or vegetation method.