TURFGRASS
Why Seeding Cool-Season Grasses in the Spring is Difficult
People often wonder why we recommend seeding cool-season grasses
such as tall fescue and Kentucky bluegrass in the fall. It would seem
that the spring would be the more natural time for seeding because the
entire growing season is available for the grass to become established
before the turf has to deal with winter. Actually there are a number of
reasons that tend to make fall seedings more successful.
The soils are warmer in the fall. Warm soils mean less time
required for germination and growth so the grass becomes established
more quickly. I have seen tall fescue seeded in the last week of August
come up in four days. Now, you had to be on your hands and knees to see
it but it was up. Tall fescue seeded in the spring may take well over a
week to come up and the time required to become established is much longer.
Weeds are less of a problem in the fall. The major weed problems in
the fall tend to be the broadleaves such as chickweed, henbit or
dandelion. Turf seeded in early September is usually thick enough by the
time these broadleaves germinate that often there is not much weed
invasion. Even if there is some invasion by broadleaves, the turf should
be mature enough by early November that mild broadleaf herbicides can be
applied.
In the spring, our major weed problems are the annual grasses such
as crabgrass. Since the spring-seeded turf is slow to mature, there are
often thin areas that are easily invaded by these grassy weeds. If this
invasion occurs, the weeds are better adapted to our hot, summer
conditions than our cool-season grasses and so the weeds tend to take
over. The number of chemicals that can be used on young turf is limited,
and so these grasses become more of a problem. One of the preemergence
herbicides that can be used on young grasses is dithiopyr (Dimension).
It is found in Hi-Yield Turf and Ornamental Weed & Grass Stopper and
Bonide Crabgrass & Weed Preventer and can be used on tall fescue,
Kentucky bluegrass, and perennial ryegrass two weeks after germination.
Summer is the hardest time of the year for cool-season grasses; not
the winter. Summertime is very difficult because our cool-season grasses
do not have the heat or moisture stress tolerance that our warm-season
grasses such as buffalo, zoysia and Bermuda have. Therefore they tend to
become weakened in the summer which makes them more susceptible to
disease and other stresses. Spring-seeded cool-season grasses are less
mature and therefore less able to tolerate these stresses.
Seeding cool-season grasses in the spring can be successful but is
more difficult to pull off than fall seedings. If you have a choice,
always opt for seeding cool-season grasses in the fall. (Ward Upham)
Lawn Calendar for Warm-Season Grasses
Following is a lawn calendar for zoysiagrass and bermudagrass.
Buffalograss, also a warm-season grass, is covered in a separate article.
March
Spot treat broadleaf weeds if necessary. Treat on a day that is 50
degrees F or warmer if possible. Rain or irrigation within 24 hours of
application will reduce effectiveness.
April
Apply crabgrass preventer between April 1 and April 15, or apply
preventer when the eastern redbud is approaching full bloom. If using a
product with prodiamine (Barricade), apply two weeks earlier. Crabgrass
preventers must be watered in before they will start to work.
May – August 15
Fertilize with 1 lb. of nitrogen per 1,000 square feet per application.
Follow the recommendations on the bag. More applications will give a
deeper green color, but will increase mowing and lead to thatch buildup
with zoysiagrass. Bermudagrass can also have problems with thatch
buildup but thatch is less likely with Bermuda than zoysia.
Bermudagrass – Use two to four applications.
Zoysiagrass – Use one to two applications. Too much nitrogen leads
to thatch buildup.
One Application: Apply in June.
Two Applications: Apply May and July.
Three Applications: Apply May, June, and early August.
Four Applications: Apply May, June, July, and early August.
June
If grubs have been a problem in the past, apply a product containing
imidacloprid by mid July. Imidacloprid can be applied as early as mid
May if there are problems with billbugs or May beetle grubs. These
products kill the grubs before they cause damage. They are effective and
safe but must be watered in before they become active. June is a good
time to core aerate a warm-season lawn. Core aeration will help
alleviate compaction, increase the rate of water infiltration, improve
soil air exchange and help control thatch.
Late-July through August
If you see grub damage, apply a grub killer. If Imidacloprid has been
applied, this should not be necessary. Grub killers must be watered in
immediately.
Late October
Spray for broadleaf weeds if they are a problem. Treat on a day that is
at least 50 degrees F. Rain or irrigation within 24 hours reduces
effectiveness. Use the rates listed on the label for all products
mentioned. (Ward Upham)
Lawn Calendar for Buffalograss
General Comments
Buffalograss has become more popular in recent years due to its
reputation as a low-maintenance grass. Buffalograss can survive with
less water and fertilizer than our other turfgrasses.
March
Spot treat broadleaf weeds if necessary. The most important treatment
for broadleaf weeds should be in late October to early November well
after the buffalograss is dormant. Treatments are much more effective
then than in the spring as the weeds are smaller and the weeds are
sending energy, as well as the herbicide, to the roots. Treatments in
March are to take care of any “escapes” missed in the fall spraying.
Spray early enough in March that the buffalograss is still dormant.
Look at the base of the plants to make sure there is no green. Try to
treat on a day that is 50 degrees F or warmer. Rain or irrigation within
24 hours of application will reduce effectiveness. Use a combination
product such as Trimec, Weed-B-Gon or Weed-Out. Weed Free Zone is also
good and will give quicker results under cool conditions.
April
Apply crabgrass preventer between April 1 and April 15, or apply
preventer when the eastern redbud is in full bloom. If using a product
with prodiamine (Barricade), apply two weeks earlier. Crabgrass
preventers must be watered in before they will work. Avoid using
broadleaf herbicides as the buffalograss is greening up as injury can
result. The buffalograss will not be killed but growth will slow making
the buffalograss less competitive with weeds.
June
Fertilize with 1 lb. of nitrogen per 1,000 square feet during June. More
applications will give a deeper green color. If it is felt that a second
application is needed, apply in July. If grubs have been a problem in
the past, apply a product containing imidacloprid by mid-July.
Imidacloprid can be applied as early as mid May if there are problems
with billbugs or May beetle grubs. These products kill the grubs before
they cause damage. They are effective and safe but must be watered in
before they become active. Again, treat only if grubs have been a
problem in the past. Note that the whole area may not need to be
treated. The beetles that lay the eggs for the grubs are attracted to
lights and moist soil and those areas are most likely to be infested.
Late-July through August
If you see grub damage, apply a grub killer. If imidacloprid has been
applied or if grubs have not been a problem in the past, this should not
be necessary. Grub killers must be watered in immediately.
Late October to Early November
Spray for broadleaf weeds if they are a problem. Look carefully as our
winter annuals such as chickweed and henbit are small and easily
overlooked. Use a product that contains 2,4-D as it increases
effectiveness on dandelions. Treat on a day that is at least 50 degrees
F. Rain or irrigation within 24 hours reduces effectiveness. Use the
rates listed on the label for all products mentioned. (Ward Upham)
It’s Not Too Late for Dormant Overseeding of Turfgrass
As mentioned in a companion article in this newsletter, the best
time to overseed cool-season grasses such as tall fescue and Kentucky
bluegrass is September because the turf has more time to mature before
crabgrass germination in the spring and the heat stress of summer.
However, dormant seeding of turfgrass is sometimes used to help fill in
bare spots of lawns that weren’t overseeded in the fall. Dormant seeding
is normally not used to seed large areas because of the possibility of
erosion before the seed emerges and becomes mature enough to hold the soil.
Dormant overseeding is usually done during the winter (December
through February) when it is too cold for germination to take place.
Spring seedings done in March can be just as successful as dormant
seeding, but spring rains may delay plantings. As with any seeding
program, it is vital that good seed-soil contact is achieved. There are
several methods that are commonly used in dormant seeding.
One method is to seed when there has been a light snowfall of up to
an inch over unfrozen soil. This is shallow enough that bare spots can
still be seen. Spread seed by hand on areas that need thickening up. As
the snow melts it brings the seed into good contact with the soil where
it will germinate in the spring.
Another method is dependent on the surface of the soil being moist
followed by some freezing weather. As moist soil freezes and thaws,
small pockets are formed on the wet, bare soils which are perfect for
catching and holding seed. As the soil dries, the pockets collapse and
cover the seed.
If dry enough and the soil is unfrozen, seed can be applied to bare
spots and then raked in to ensure good seed/soil contact.
With any of the above methods, seed germinates in the spring as
early as possible. There will be limitations on what herbicides can be
used for weed control. Tupersan (siduron) can be used as a crabgrass
preventer on new seedings even before they have come up. Also dithiopyr,
found in Hi-Yield Turf and Ornamental Weed & Grass Stopper and Bonide
Crabgrass & Weed Preventer, can be used on tall fescue, Kentucky
bluegrass, and perennial ryegrass two weeks after germination. Dithiopyr
is longer lasting and more effective than siduron. Other preemergence
herbicides available to homeowners require that the turf be well
established before application. (Ward Upham)
FRUIT
Growing Blueberries
Blueberries are not native to Kansas and are difficult for us to
grow. However, they will grow in the eastern half of the state though
good preparation before planting is vital. Blueberries are related to
azaleas and rhododendrons and require an acid pH, preferably 4.8 to
5.2. Blueberries do not have root hairs, so watering and mulching are
important.
It is best to start planting preparations a year ahead of time to
allow for pH adjustment, weed control, and the addition of organic
matter. The first step is a soil test to determine how much the pH needs
to be reduced. For a pH up to 5.5, the addition of sphagnum peat moss at
the rate of 2 cubic feet per 100 square feet will be adequate. For a pH
5.5 to 6.0, add 1 pound of sulfur per 100 square feet of bed in addition
to the peat moss. For a pH 6.0 to 6.5, add 1.5 pounds of sulfur per 100
square feet of bed. For pH levels above 6.5, use 2 pounds of sulfur per
100 square feet of bed and double the amount of sphagnum peat moss
suggested earlier. Do not use aluminum sulfate to correct a high pH
because excessive levels of aluminum can be toxic to blueberries. For
each 0.5 movement up the pH scale from 6.5, add an additional pound of
sulfur. Sulfur can be applied as a dust, but pelletized sulfur is much
easier to spread.
Treat only the row. Row width should be 8 feet. Blueberries are
normally spaced about 5 feet within the row. Sulfur takes time to react,
so allow as much time as possible between sulfur application and
planting. Blueberries will bear more if you plant more than one variety.
Recommended varieties vary, but you may want to try Bluecrop
because it is adaptable. Patriot also seems to do well. You may want to
try some other varieties. Blueberries should be mulched. Sawdust is the
traditional material, but straw and wood chips will work as well. Mulch
to a depth of about 3 inches.
Blueberries must be irrigated. Soils should be kept moist but never
waterlogged. Adding peat moss to the planting row will elevate the
planting bed enough that standing water should not be an issue. However,
an elevated bed will dry out more quickly, so there must be a means of
adding water. Trickle irrigation works well. Watering twice a week
during the summer with enough water to wet the soil 8 inches deep should
be sufficient except under extreme heat. Watering once a week may be
enough during the cooler spring and fall weather. As you might guess,
there is more to growing blueberries than can be included in a short
article. Dr. Art Gaus from the University of Missouri shared this
instruction sheet on how to grow blueberries more than 25 years ago. It
is still excellent information on blueberry culture. You can access it
by going to:
http://hnr.k-state.edu/doc/extension-gardening-tips/Blueberry_Production.pdf
Blueberries require commitment. Anything less than excellent
preparation and care will result in failure. (Ward Upham)
Blueberries in Containers
Growing blueberries in containers is becoming more popular due to
the difficulty in growing them in our native Kansas soils (see
accompanying article). Chosen varieties are usually half-high plants
that are a cross between highbush and lowbush blueberry species. Plants
can be as small as 18 inches tall and wide (Top Hat), but typically are
larger. Here are several tips for producing container grown blueberries:
Acid soil pH: Blueberries need an acid pH between 4.8 and 5.2.
Sphagnum peat moss is very acid and often used in large quantities in
soil mixes for acid-loving plants. In fact, blueberries can be grown in
peat moss alone if nutrients are provided but that is an involved
process. A 50/50 mix of peat moss and potting soil is recommended. This
will provide nutrients and weight so the plant is less likely to blow
over in wind.
Container size: Though containers as small as 2 gallons can be used
for half-high blueberries, a larger container will be more stable in the
wind and provide a larger moisture reserve during hot, dry weather.
Watering: Blueberries do not have root hairs, so they are not
efficient in picking up water. Potting soil should be kept moist. This
will likely be the most challenging aspect of growing blueberries in
containers. A large container will not need to be watered as frequently
as a small one.
Winter care: Though plants are winter hardy, the roots are not. Move
pots into an unheated, attached garage or bury them in the soil or mulch
enough to bury the pot in early November. Water them periodically during
the winter. Use your finger to determine if the soil is moist one inch
deep. If not, then water until some flows out the bottom of the pot.
Varieties: Though blueberries will produce some fruit if only a
single variety is grown, two varieties will increase the potential fruit
crop. Suggested varieties include Top Hat and Northsky. Each should
reach about 18 inches high, though Northsky will likely grow wider than
Top Hat. Northblue is another choice that should produce more fruit than
either Top Hat or Northsky but should reach 2 to 3 feet high. North
Country is intermediate in size at 18 to 24 inches high and should
produce a moderate amount of fruit.
Wind protection: Wind protection will decrease the amount of water
these plants need and reduce the chances of leaf scorch.
Exposure: Blueberries do best with a minimum of 6 to 8 hours of
sunlight a day. Try a northern or eastern exposure that is protected
from the wind. (Ward Upham)
MISCELLANEOUS
Establishing a Wildflower Area
Native grasses and many native wildflowers do well within a wide pH
range. Any pH between 5.5 and 8 should work. Just make sure the area
receives at least 8 hours of sun a day.
It is better to choose a blend of grasses and wildflowers rather
than a single species. Companies that provide regional blends include
Sharp Brothers, Stock Seed and Wildseed Farms.
These plants do not take root and grow well in areas that already
have established plants. Existing vegetation should be killed before
seeding. Follow the following steps to increase the chances of success.
– Control perennial weeds by using a product containing glyphosate.
– Using glyphosate the fall before planting makes soil preparation
easier the following spring
– Adjust pH and fertilize according to soil test before planting.
– The seedbed should be firm so that a boot heel sinks in no more
than ½ inch.
– The goal is good seed/soil contact.
– Can mix seed with damp sand (4:1 sand/seed) for more uniform
coverage with a drop seeder or whirlybird spreader.
– The seed should be raked in about 1/4″ deep. It is best if the
seedbed is firmed up by using roller or driving over the area with a
riding lawn mower. Don’t mulch.
– Keep seed moist while the seed is germinating (3 to 4 times per
week, if possible). Slowly back off watering as plants develop.
What about planting dates? Warm-season grasses and most prairie
flowers should be seeded between April 1 and May 15. To control any
remaining living vegetation, spray with a product containing glyphosate,
wait a week and plant. Make sure the soil temperature is at least 60
degrees before planting. Soil thermometers are often available in garden
centers, hardware stores and auto stores (they are used to test air
temperatures from air conditioners as well as in gardens).
Hand weeding can help but must be done with care to avoid uprooting
small prairie flowers. Mowing as high as possible can help control fast
growing weeds while preserving most of the foliage on the prairie
flower. (Ward Upham)
Contriubtors: Ward Upham, Extension Associate
Division of Horticulture
1712 Claflin, 2021 Throckmorton
Manhattan, KS 66506
(785) 532-6173
For questions or further information, contact: [email protected] OR
[email protected]
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