According to Growth Habits
Before planting you should
also understand the growth habit of the grass. Grasses can be either
clump forming or rhizome forming. The latter is often called
"running" grass (yes, it can be invasive and will vary from
area to area - check with your country extension office before you
plant). The clump forming grasses will grow in very nice, neat mounds
or clumps. They tend to mix very well with other perennials and will
not become invasive. They will increase in girth slowly over time.
Make sure you choose a
grass the right size and shape for your landscape needs. Some
ornamental grasses get extremely tall! Grasses are also
available with variegated leaves - these can be horizontal or vertical
bands of color, patches, stripes or spots. Textures vary from
very fine and feathery to thick strap-like blades. The late
summer and autumn seed heads vary widely too - from frothy or
feather-like whites, pastels and deep, bright colors, to the more
coarse bead-like or rope-like types. The best ornamental grass
gardens will include a collection of different types that provide
size, color, seed head, and texture contrast.
The rhizome forming
grasses spread by underground stems and can become very aggressive and
invasive. These grasses have their place but it may not be in a
well-tended perennial border since they can soon take over an entire
Before selecting a grass,
be sure to understand how it grows so you won’t be planting a future
problem. Some attractive but aggressive grasses include Blue
Lymegrass, Cordgrass, Ribbongrass, and Silver
Banner Grass (miscanthus sacchariflorus) These can be useful
for covering slopes to prevent soil erosion, but do use them with
Cool season grass will
start to grow early in the spring and may even remain semi-evergreen
over the winter. They also seem to do better and have better
foliage when they are cool or if they are given sufficient water
during drought periods. If they are not watered during drought, they
tend to go dormant resulting in brown foliage.
These grasses may require
more frequent division to keep them healthy and vigorous. If
not, they tend to die out in the center. For the ones that remain
semi-evergreen, you should only cut off the brown or winter injured
foliage in the spring. Some of the more popular cool season grasses
include, Fescues, Blue Oat Grass (Helictotrichon), Tufted
Hair Grass (Deschampsia), and Autumn Moor Grass (Sesleria).
Warm season grasses will
do better during warmer times of the year and remain good looking even
when temperatures are high and moisture is limited. Warm season
grasses do not begin to show growth until the weather becomes stable
and the soils warm. The previous seasons growth usually browns out in
the fall requiring the cutting back of plants to about 4-6 inches in
Japanese Silver Grass
Warm season grasses
usually do not require as frequent division as cool season grasses.
Some warm season grasses include Northern Sea Oats (Chasmanthium),
Japanese Silver Grass (Miscanthus sp.), Hardy
Pampas Grass (Erianthus and Cortaderia), Perennial
Fountain Grass (Pennisetum), and Switch Grass (Panicum).
As with any perennial,
preparing the soil before planting will insure success.
Prepare the bed by deep tilling and adding organic material.
Ornamental grasses do not require high amounts of fertilizer. Adding
about one pound of a general-purpose fertilizer (like 10-10-10) during
soil preparation per 100 sq. ft. of planting bed should be sufficient.
Ornamental grasses can be
planted in the spring or the fall. The advantage of spring planting is
to give the plants adequate time to develop a good root system before
winter. Fall planting is often not as reliable without some additional
precautions, particularly in years with early or severe winters. You
should try to complete fall planting during August and September. Then
provide a light cover of straw or hay during the first winter for best
Apply the mulch after
several hard frosts. Plants should be planted no deeper than their
previous growing depths and should be well watered after planting.
Maintaining uniform soil moisture around the plant hastens
establishment. Plants planted too deep tend to develop root diseases
or simply rot in the ground.
Perennial grasses can be
propagated by seed sown in spring or autumn. Established clump
forming plants can be lifted and split in the spring. Grasses
that form rhizomes can be propagated by cutting the rhizome into
sections (each with at least one growing point) and each section
planted at the same depth as when it was lifted from the mother plant.
Plants should be well
watered the first season after planting so they can develop a good
root system. Established plants do not need regular watering, but may
need supplemental watering during drought periods. The amount of water
will depend on the grass species, the site, and on the quality, size
and growth rate desired.
If your area is too moist,
increase soil drainage by mixing in sharp sand, or stick to growing
sedges or rushes and other ornamental grass types recommended for
moist soils (see below).
Cultivate around grass
plants to control weeds. Apply mulch to reduce the need for
cultivation as well as watering. Mulching also tends to keep grasses
in check that have a tendency to be heavy reseeding types.
Protection and Spring Clean up
Grasses do not need to be
cut down before winter. In fact, they make a stunning contrast in the
winter garden when left standing, plus the foliage helps to insulate
the crown of the plant. Cut back the foliage to about 4-6 inches in
the spring before growth resumes. When foliage is removed, spring
growth will begin earlier. Old foliage left on the plant can delay the
crown’s warming and growth by as much as 3 weeks.
To divide your
plants depends on how they are spaced and how they look, the appearance
of the plants as well as the health should determine if it needs
dividing.. Plants suffering from die-out in the center should be
divided to improve appearances. Division is done in the spring before
growth resumes or in the late summer or fall after the growing season.
Plants that bloom late could be divided in the spring.
Ornamental grasses are
not bothered by pests, but if you see Aphids, then spray the plant
with water from a hose to dislodge the critters.