TURFGRASS
Lawn Calendar for Cool-Season Grasses
The following suggestions are for cool-season grasses such as
Kentucky bluegrass or tall fescue. Zoysiagrass, bermudagrass, and
buffalograss are warm-season grasses and require a different maintenance
regime. A warm-season grass calendar will be covered in a later newsletter.
March
Spot treat broadleaf weeds if necessary. Treat on a day that is 50
degrees or warmer. Rain or irrigation within 24 hours of application
will reduce effectiveness.
April
Apply crabgrass preventer when redbud trees are in full bloom, usually
in April. The preventer needs to be watered in before it will start to
work. One-quarter inch of water will be enough to water in any of the
products mentioned in this calendar. Remember that a good, thick lawn is
the best weed prevention and may be all that is needed.
May
Fertilize with a slow-release fertilizer if you water your lawn or if
you normally receive enough rainfall that your turf doesn’t go
drought-dormant during the summer. If there are broadleaf weeds, spot
treat with a spray or use a fertilizer that includes a weed killer. Rain
or irrigation within 24 hours of application will reduce effectiveness
of the weed killer, but the fertilizer needs to be watered in. If you
are using a product that has both fertilizer and weed killer, wait 24
hours after application before watering in.
June through Mid-July
Apply second round of crabgrass preventer by June 15 – unless you have
used Dimension (dithiopyr) or Barricade (prodiamine) for the April
application. These two products normally provide season-long control
with a single application. Remember to water it in. If grubs have been a
problem in the past, apply a product containing imidacloprid during the
first half of July. This works to prevent grub damage. If rainfall does
not occur within 24 hours, irrigate with 1/4″ of water.
Late-July through August
If you see grub damage, apply a grub killer that contains Dylox.
Imidacloprid is effective against young grubs but may not be effective
on late instar grubs. The grub killer containing Dylox must be watered
in within 24 hours or effectiveness drops.
September
Fertilize around Labor Day. This is the most important fertilization of
the year. Water in the fertilizer.
November
Fertilize. This fertilizer is taken up by the roots but is not used
until the following spring. Water in fertilizer. Spray for broadleaf
weeds even if they are small. Broadleaf weeds are much easier to control
in the fall than in the spring. Try to spray on a day that is at least
50 degrees. Rain or irrigation within 24 hours reduces effectiveness.
Use label rates for all products! (Ward Upham)
VEGETABLES
Planting Asparagus
Though it is too early to plant asparagus, it is not too early to
make plans and prepare the soil. This crop is a perennial and will
survive for many years if given proper care. It prefers full sun and a
well-drained soil and is usually placed on the edge of the garden area
so that there is no need to till around the area to plant other crops.
Proper soil prep is especially important for perennial crops. Take
a soil test to ensure proper levels of nutrients. See the accompanying
article on how to take a soil test for the correct procedure.
Work the soil as early in the spring as possible but do not work
wet soil as clods will form. Then add two inches of organic matter to
the surface and the fertilizer and work again so the organic matter and
fertilizer are blended into the soil.
Asparagus can be propagated from seed but is more often started
from 1-year-old crowns. These crowns are planted deeply; 6 to 8 inches
deep either in a hole for each crown or in a trench with shallower
planting recommended for soils with more clay. Space plants 18 to 24
inches apart. Fill in the trench gradually over the growing season to
encourage growth.
March 15 to April 15 is the best planting time. Adapted varieties
include Jersey Giant, Jersey King, Jersey Knight, Jersey Supreme and
Purple Passion. These are all male hybrids that will produce three times
as much as our old Martha or Mary Washington varieties. Males have a
number of advantages over females in that they live longer, emerge
earlier in the spring, are more productive and eliminate potential
volunteer plants that can reduce the productivity of a planting.
Weed control is very important. Competition with weeds results in
slow establishment. A shallow hoeing should be all that is needed. (Ward
Upham)
FLOWERS
Fertilizing Spring-flowering Bulbs
The best time to fertilize spring-flowering bulbs is when foliage
emerges in the spring rather than at flowering. Traditionally, gardeners
have applied fertilizer during bloom or a bit after, but because bulb
roots start to die at flowering, fertilizer applied at bloom is wasted.
Roots are active when the foliage first pokes through the ground.
Nutrients applied then help the plant produce flowers the following
year. If bulbs have been fertilized in the past, there is often plenty
of phosphorus and potassium in the soil. It is best to take a soil test
to be certain.
If the soil needs phosphorus and potassium, use a complete
fertilizer (such as 10-10-10, 9-9-6, etc.) at the rate of 2.5 lbs. per
100 square feet. This would equal 1 rounded teaspoon per square foot. If
phosphorus and potassium are not needed, blood meal makes an excellent
fertilizer. It should be applied at the rate of 2 lbs. per 100 square
feet or 1 teaspoon per square foot. Lawn fertilizers such as a 27-3-3 or
30-3-3 can be used, but cut the rate by a third. Also make sure the lawn
fertilizer does not contain a weed preventer or weed killer.
Remember to leave the foliage until it dies naturally. The energy
in the foliage is transferred to the bulb as the foliage dies and will
help the bloom for the next year. (Ward Upham)
MISCELLANEOUS
Gardening Calendar
The Kansas Healthy Yards website has a gardening calendar that many
gardeners find helpful. It lists all the months of the year and the
chores that can be done during that month. Each month is divided into
separate sections such as Vegetables and Fruits, Flowers, Lawns, Trees
and Shrubs and Houseplants. Not all suggestions will be helpful each
year but are important to have included. For example, one of the
January tips is on removing snow and ice on limbs. You may brush off
the snow, if desired, but ice should be allowed to melt naturally.
To find the gardening calendar, go to
http://kansashealthyyards.org/ and click on “Gardening Calendar” in the
gray bar at the top of the page. (Ward Upham)
Soil Testing
Most gardeners think that soil tests are done only to find out what
nutrients are deficient. However, it is just as important to know if you
have adequate levels of nutrients so you don’t add unneeded fertilizer.
The most basic soil test checks pH and the levels of phosphorus and
potassium. Most of the lawn and garden soil tests that come out of our
soil-testing lab show more than adequate levels of both phosphorus and
potassium. If those nutrients are not needed, applying them is a waste
of money and can be a source of pollution. In extreme cases, excess
phosphorus can interfere with the uptake of micronutrients. So, if you
haven’t taken a soil test in several years, take one this spring.
Begin by taking a representative sample from a number of locations
in the garden or lawn. Each sample is composed of about 8 sub-samples
that go from the surface to 6 to 8 inches deep. Mix the sub-samples
together in a clean container and select about 1 pint of soil. For more
detail on taking a soil test, click here and choose “Soil Analysis” in
the left column.
Take the soil to your local K-State Research and Extension office
to have tests done at the K-State soil-testing laboratory for a fee. A
soil test determines fertility problems, not other conditions that may
exist such as poor drainage, poor soil structure, soil borne diseases or
insects, chemical contaminants or damage, or shade with root competition
from other plants (see accompanying article). All of these conditions
may reduce plant performance but cannot be evaluated by a soil test.
(Ward Upham)
Soil Tests When Soils are Wet
If your soil is wet, it would be best to wait until the soil dries
before taking samples. Though it is possible to take soil tests when
soils are wet, there are precautions.
Soil samples should be air-dried before being submitted for
testing. Do NOT use artificial means of drying such as an oven or
microwave as such treatment may result in inaccurate readings of
nutrient levels. Also, be sure to use a clean container to collect the
sample. Wet samples are more likely to absorb foreign materials adhering
to the container, which may also influence soil test results.
For more detail on taking a soil test, click here and choose “Soil
Analysis” in the left column. Then click “Sample Collection” at the
bottom of the center column.
Take the sample into your local extension office. If you don’t know
the address for your local, county extension office, see
http://www.ksre.ksu.edu/Map.aspx (Ward Upham)
What a Soil Test Does Not Tell You
Though soil tests are useful for identifying nutrient deficiencies
as well as soil pH, they do not tell the whole story. We often receive
soils from gardeners that are having a difficult time growing crops even
though the soil test shows the pH is fine and nutrients are not
deficient. Here are some factors that can affect plant growth that are
not due to nutrient deficiencies or pH.
Not enough sun: Plants need a certain minimum amount of sun before
they will grow well. As a general rule, flowering (and fruiting) plants
need at least 6 to 8 hours of full sun per day. There are, of course,
exceptions such as impatiens that bloom well in shade. Move sun-loving
plants into more sun or use plants that are better adapted to shady
conditions.
Poor soil physical characteristics: Roots need oxygen as much as
they need water. A tight clay soil or excessive water can restrict soil
oxygen levels as well as make root penetration of the soil difficult.
Increasing the organic matter content of clay soils can help rebuild
good structure. Add a 2-inch layer of organic matter and till it in.
Walnut trees: Walnuts give off a natural herbicide that interferes
with the growth of some plants such as tomatoes. Vegetable gardens
should be at least 50 feet away from walnut trees if possible. For a
listing of plants that are susceptible to walnut, go to:
http://www.omafra.gov.on.ca/english/crops/facts/info_walnut_toxicity.htm
Tree roots: Trees not only compete with other plants for sun but
also for water and nutrients. Extra water and nutrients may be needed.
Shallow soils: When new homes are built, the topsoil is often
stripped off before the soils are brought to grade. Though the topsoil
should be replaced, it sometimes is not or is not replaced to the same
depth as it was originally. You are left with a subsoil that usually
does not allow plants to grow well due to a lack of soil structure.
Adding topsoil to a depth of 8 to 12 inches would be best but this often
is not practical. In such cases, try to rebuild structure by adding
organic matter and working it into the soil.
In other cases, a thin layer of soil may be spread over rock or
construction debris. Plantings in shallow soils will wilt and die more
quickly than other plants that are on a deeper soil. Use a soil probe to
find such obstructions.
Too much phosphorus: Most Kansas soils are naturally low in
phosphorus. However, soils that have been fertilized for a number of
years may have phosphorus levels that are quite high. As a matter of
fact, the majority of soil tests we receive show phosphorus levels in
the “high” category. Extremely high phosphorus levels can interfere with
the uptake of some micronutrients such as iron, manganese and zinc.
High phosphorus soils should only be fertilized with fertilizers that
have relatively low amounts of phosphorus.
Improper watering: Roots develop where conditions are best for
growth. Shallow, frequent watering leads to roots developing primarily
near the surface of the soil where the soil is moist. Such shallow root
systems are easily damaged by heat and any interruption in the watering
schedule. It is better to water less frequently and to a greater depth
to encourage a deeper root system that is less sensitive to heat and
water stress.
Watering during the evening can also be detrimental to plants if
the irrigation wets the foliage. Many diseases are encouraged by free
water on the leaves. Watering late in the day often will keep the
foliage wet until dew forms. Dew will keep the foliage wet until it
evaporates the next morning. It is better to water early in the morning
so leaves do not stay wet as long. If you must water late in the day,
use drip irrigation if practical (such as in a vegetable garden).
Overwatering: Roots need to breathe. In other words, they must have
oxygen in order to survive. Be careful to not water so heavily that the
soil remains saturated. Water deeply but allow soil to dry somewhat
between waterings. (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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(K-State Research and Extension)
