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| Ruby Muhly Photo: Plant Select |
As we see plants in our garden die off, some of us might
have the urge to tidy everything up. One of the plant categories that can
benefit most from a hands-off approach are the ornamental grasses.
There are many reasons to leave these grasses standing over
the winter months. Their foliage and seed heads offer texture, movement, and
beauty in the winter. They'll also be illuminated by the low angled winter sunshine.
Plus, many beneficial insects use these grasses to provide protection for
overwintering egg masses, larvae, and adult forms. Leaving ornamental grasses
standing until late spring gives the insects time for their eggs to hatch and
their larvae to change into adults. Birds will also use standing grasses as
sources for seed and winter shelter.
There are basically three types of ornamental grasses:
Warm-season grasses that begin growing in mid to late spring (warmer
temperatures); Cool-season grasses grow best when temperatures are cooler, between
60-75 degree F, which is why they grow most actively in the spring and fall; Evergreen
grasses remain mostly green through the year and do not need to be cut back.
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Blonde Ambition (Grama Bouteloua)
Photo: Pexels Doreen Wynja |
Warm-season grasses begin growing in mid to late spring, or
even early summer. They thrive when the temperatures rise, with major growth
and flowering occurring during summer's heat. Warm-season grasses turn brown in
winter. Warm-season grasses should be cut back in mid-spring. This will protect
the crown of the plant, and encourage new growth as temperatures warm. The
exception to this is areas of high fire danger where you should prune them
after they go brown. Warm-season grasses include Little Bluestem
(Schizachyrium), Big Bluestem (Andropogon), 'Blonde Ambition' Blue Grama
(Bouteloua), Muhly (Muhlenbergia), Switchgrass (Panicum), Maidenhair Grass
(Miscanthus), Giant Sacaton (Sporobolus wrightii.) Other common warm-season grasses
include northern sea oats (Chasmanthium), Japanese silver grass (Miscanthus
sp.), hardy pampas grass (Erianthus), perennial fountain grass (Pennisetum),
switchgrass (Panicum), and prairie cordgrass (Spartina). When you prune these
warm-season grasses, cut them severely, right down to the ground. |
| Karl Foerster' Feather Reed Grass (Calamagrostis). |
Cool-season grasses have evergreen foliage that should not
be cut to the ground. Instead, vigorously "comb out" dead leaves with
gloved hands and clip off the dead leaf tips in late fall. Then in very early
spring, cool season grasses should be cut back. As soon as the snow clears, cut
the grass back by two-thirds, leaving one-third in place. Pruning too
drastically can harm the plant. Some examples of cool season grasses include
fescues, blue oat grass (Helictotrichon), tufted air grass (Deschampsia), and
autumn moor grass (Sesleria.) In early spring, clip off old seed heads from
stalks as far down into the foliage as possible to leave room for late spring
flowers. Other cool-season grasses include Blue Avena Grass (Helictotrichon),
Fescue Grass (Festuca), Silky Thread Grass (Nassella) and 'Karl Foerster'
Feather Reed Grass (Calamagrostis).
If you
have evergreen ornamental grasses, don’t cut them back; instead, simply remove
the old leaves or blades in early spring. Examples of evergreen grasses are
sedges (Cyperaceae,) and blue oat or avena grasses (Helictotrichon sempervirens.)
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Giant sacaton(Sporobolus wrightii)
Photo: Plant Select |
If the grass plant has a ring of living leaves with a dead
center, it's time to divide the grasses to re-invigorate them. This is
necessary once every three to five years depending on the species and growing
conditions.
The following were used as sources and have very good
information about ornamental grasses:
https://extension.colostate.edu/topic-areas/yard-garden/ornamental-grasses-7-232/?fbclid=IwAR2WhY7eyrOF6-wtWizXquL3mNTBRn4RIsWH9PqDoZEHXKtpNgzXgmhoXfw
https://www.highcountrygardens.com/gardening/fall-garden-clean-up-dont-prune-these
https://web.extension.illinois.edu/grasses/
https://gazette.com/news/ornamental-grasses-need-cutting-back/article_a093036e-79bc-5fe8-8288-36b8f73a64db.html
https://harlequinsgardens.com/plants/ornamental-grasses/
