Green Roofs - Living Architecture Monitor - Fall 2017 - 9

PLANT PROFILES

THE 'PERFECT' BIOPHILIC PLANT

KOELERIAMACRANTHA
DR. BRADLEY ROWE, MICHIGAN STATE UNIVERSITY, EAST LANSING

T

he theme of this Living Architecture Monitor is biophilia - a
term that literally means a love of life or living things. For
most of us, there is a psychological and/or biological need to
be connected to nature. Many studies have shown that human
beings are healthier, more productive, and experience less stress
when they have some interaction with the natural world. In line
with the concept of biophilia, plants that can move or sway in the
breeze tend to catch our eye to a greater extent than those that are
shorter or more static such as sedum or mown grass. Taller plants
also provide more structure during the winter months as they
rise above the snow. One species that is suitable for some green
roofs and also fits this description is the grass Koeleriamacrantha
(Prairie Junegrass).
Prairie Junegrass is a cool season, perennial clump-forming
grass that is native throughout much of Europe, Asia, and North
America except for the southeastern United States. It primarily
occurs in prairie habitatsat elevations from 1220 to 3660 m (4,000
to 12,000 ft) that receive 30 to 50 cm (12 to 20 in) of annual
precipitation and is classified within USDA hardiness zones 3 to
9. It naturally grows in full sun in rocky to sandy soils with good
drainage and low fertility which makes it an ideal candidate for
green roofs. The species is considered tolerant of cold, heat, and
drought, but the magnitude of its tolerance depends on the seed
source. It has survived on our roof when grown in 20 cm (8 in),
but completely died out in a depth of 10 cm (4 in) without any
supplemental irrigation.

LIVINGARCHITECTUREMONITOR.COM

The species reaches heights
from 30 to 60 cm (12 to 24
in) with a typical spread of
23 to 45 cm (9 to 18 in). The
narrow, pointed, light green
leaves are basal and relatively
short (up to 18 cm (7 in)
long). What gives the species
its height are the long flower
spikes located well above the
leaves that appear during late
spring. The green to purplish
seed heads fluff open during
flowering and become more
silver as they mature. It has
early season appeal as it greens
up early in spring and flowers
by May or June. On the down
side, even though it is one of
the first grasses to green-up in
the early spring, it may brown
out and enter dormancy during the summer in areas with
hot climates. The cooler the
climate, the longer it will last
into the fall.

Prairie Junegrass may
naturalize a roof by spreading
seed, but it is unlikely to invade
surrounding areas as it usually
spreads slowly because seedlings
are slow to establish.If sowing
seed on a roof, the area must
be maintained weed free as
the seedlings will not compete
with faster growing vegetation.
Planting plugs generally results
is greater success. It experiences
no significant insect or disease
problems, but the pollen can
make life miserable for those of
us with grass allergies.

Dr. Brad Rowe has been conducting
green roof research at MSU since
2000. He was the founding chair
of the GRHC Research Committee
and received the GRHC Research
Award of Excellence in 2008. Brad
also teaches a course on green roofs
and walls at MSU.
LIVING ARCHITECTURE MONITOR / FALL 2017 / 9
http://www.LIVINGARCHITECTUREMONITOR.COM
Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Fall 2017
