Native Plants

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Sunday - August 26, 2007

From: Brooklyn, NY
Region: Northeast
Topic: Green Roofs
Title: Green roof in New York City
Answered by: Nan Hampton and Mark Simmons

QUESTION:

Hi, I am interested in planting native plants on green roofs in New York City. I am wondering how deep your soil is on the center's native plant green roof and if it is irrigated, or was it ever irrigated, and if so for how long? Could you recommend New York State native plants that would work well in 4"-5" of soil and little irrigation? Thanks!

ANSWER:

We have 4" of synthetic soil and we do irrigate, but that's because we need our roofs to be able to transpire for storm water mitigation as well as for cooling in our sub-tropical climate. For minimal water up in the NE USA most use temperate succulent plants like sedums. There's good information on this type of green roof from Green Roof Plants. Ed Snodgrass' book, Green Roof Plants, is excellent.

According to this site, there are two types of green roofs, extensive and intensive. Extensive green roofs use low-lying plants that provide groundcover and are very drought tolerant. Intensive green roofs use plants that provide more of a natural landscape that may have heights of several feet and require deeper soil depth and irrigation.

The priniciple types of plants that Snodgrass recommends are succulents, in particular, sedums or stonecrops. This limits the native plants available that are native to New York to Sedum ternatum (woodland stonecrop).

Rhodiola rosea (roseroot stonecrop) is also native to New York, but is on the State Protected Plants in New York list, so is not really an option to use.

Here are a few suggestions for other plants native to New York that do well in the sun and require little water. They are generally low plants, <1 or 2 feet and should do well in on extensive green roof.

GRASSES

Koeleria macrantha (prairie Junegrass)

Sporobolus heterolepis (prairie dropseed)

HERBS

Antennaria neglecta (field pussytoes)

Cerastium arvense (field chickweed)

Coreopsis lanceolata (lanceleaf tickseed)

Erysimum capitatum (sanddune wallflower)

Hypoxis hirsuta (common goldstar)

Lithospermum canescens (hoary puccoon)

Rudbeckia hirta var. pulcherrima (blackeyed Susan)

Tephrosia virginiana (Virginia tephrosia)