Establishing and Managing Switchgrass 4-22-09
gengberg April 22nd, 2009
Establishing and Managing Switchgrass
Mark Renz, Dan Undersander, and Mike Casler
Switchgrass (Panicum virgatum) is a vigorous warm season, native perennial grass adapted to
Wisconsin and planted for many purposes including livestock grazing, wildlife cover, and as a
biofuel crop. Switchgrass begins growth in late spring and continues through the summer if
moisture is available. It grows 3 to 6 feet in small to large sodded clumps that spread slowly
from numerous scaly creeping rhizomes. The leaves have a bluish cast and can attain a length of
2 feet. At the junction of the leaf blade and leaf sheath the ligule is a dense ring or cup of hairs
on the upper leaf surface. The panicles are pyramid shaped with many purplish spikelets. Under
native conditions it is usually found along creeks, streams and protected areas, but establishment
and productivity has been best in fields with loam to sandy loam soils.
Switchgrass in June Four Months’ Growth in October
VARIETIES/ECOTYPES
Switchgrass varieties/ecotypes vary widely in their adaptation to environmental conditions.
Cold winters, hot summers, and day length are the most important of these environmental
factors, all of which vary according to latitude. Because of this, switchgrass varieties/ecotypes
should be moved no more than one hardiness zone from their origin. Sunburst originates within
hardiness zone 4 and Cave-in-Rock originates within hardiness zone 5. Both are well adapted to
the north central USA, with excellent tolerance to cold winters and relatively high biomass yield.
ESTABLISHMENT
Switchgrass has relatively small seed averaging approximately 370,000 seeds per pound. The
suggested seeding rate is 6 to 7 pounds of pure live seed when close drilled (8 inches or less
between rows) or broadcasted. Switchgrass should be planted in the spring after soil temperature
is above 60o F. Planting is recommended on a firm, well prepared seedbed at a depth of 1/2 to
3/4 inch. Cultipacking after planting helps establish good contact with soil and speeds
germination. No-till planting of switchgrass has also been successful in Wisconsin. If possible
plant after no-till soybeans as no-till corn fields have rougher terrain that can make harvesting of
biomass difficult. Switchgrass is slow to establish and many of the resources collected in the
establishment years are used to develop an extensive root system. Due to this, switchgrass
should not be grazed or cut during the seeding year unless weed density is high or growth is
exceptional.
WEED MANAGEMENT
Several management methods can be utilized for managing weeds while establishing
switchgrass. Selection of the most appropriate method is based on the weed species present and
the appropriate density. In general, sites with extensive perennial grass infestations (e.g.
quackgrass) should be avoided as they are difficult to manage while establishing switchgrass. If
possible, reduce the weed populations as much as possible before planting. This can be done
with repeated cultivations and/or burndown herbicide applications before planting switchgrass.
Growing roundup ready corn or soybeans year(s) prior to establishment of switchgrass is also
effective in reducing weed populations, especially perennial weeds.
Annual broadleaf weeds are common in the establishment year and if populations are dense,
establishment can be reduced. These weeds can be controlled with timely mowing and/or the
use of a labeled broadleaf herbicide. If mowing, leave at least 6 inches of stubble.
If a broadleaf herbicide is used, wait until switchgrass plants have at least 3-4 leaves (or are 3-4
inches tall) before application to avoid injury. Weedy grasses can also be troublesome as they
are much more difficult to control without injuring switchgrass seedlings. Research has
evaluated the effectiveness of Certainty, Drive, Journey, and Pursuit on grasses as well as
broadleaf weeds and the potential for injury to switchgrass seedlings. While these herbicides are
registered for applications at various times, best results have been seen with pre-emergent
applications. Post-emergent timings do provide weed suppression, but are not recommended to
be applied until 3-4 leaves are present. This delay in application has resulted in reduced
establishment and productivity compared to pre-emergent applications. Injury has been observed
with Certainty, Journey, and Pursuit, but switchgrass seedlings outgrew this injury
Please note that Journey can only be applied pre-emergent and atrazine is not registered for use
in switchgrass in Wisconsin. Once fields are established it is not expected that additional weed
management will be necessary.
Herbicides for use in establishing switchgrass Continue Reading »
