09 February 2016 |

Horticulture Newsletter 2016, No. 6

Written by K-State Horticulture Newsletter - Newsletters

Video of the Week:
How to Water Succulents and Cacti

Turfgrass:
Lawn Calendar for Cool-Season Grasses

Tall Fescue lawn
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 receive enough rainfall that your turf normally 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. It must be watered in before it becomes active.
 
Late-July through August
If you see grub damage, apply a grub killer that contains Dylox. Imidacloprid is effective against young grubs and 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. Spray on a day that is at least 50 degrees. Rain or irrigate within 24 hours reduces effectiveness. Use label rates for all products! (Ward Upham)

Flowers:
Handling Tips for Valentine's Day Roses

Valentine's Rose
If you are fortunate enough to receive roses from a loved one this Valentine's Day, follow these guidelines to help extend the life of your flowers.
 
For floral arrangements:
1) Keep the vase filled or floral foam soaked with warm water. Add fresh, warm water daily. If the water turns cloudy, replace it immediately. If possible, recut stems by removing one to two inches with a sharp knife. Do this under water. This allows the stems to draw in water instead of air.
 
2) Keep flowers in a cool spot (65 to 72 degrees Fahrenheit), away from direct sunlight, heating or cooling vents, directly under ceiling fans, or near radiators.
 
3) If a rose starts to wilt, remove it from the arrangement, and recut the stem under water. Submerge the entire rose in warm water. The rose should revive in one to two hours.
 
For loose stems:
1) If you can't get your flowers in a flower food solution right away, keep them in a cool place.
2) Fill a clean, deep vase with water and add the flower food obtained from your florist. Be sure to follow the directions on the package.
 
3) Remove leaves that will be below the waterline. Leaves in water will promote bacterial growth.
 
4) Recut stems under water with a sharp knife and place the flowers in the vase solution you've prepared. (Ward Upham)

Miscellaneous:
Soil Testing

soil testing tools
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 that goes from the surface to 6 to 8 inches deep. Mix the samples together in a clean container and select about 1 pint of soil. For more detail on taking a soil test, see the K-State Dept of Agronomy instructions.
 
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 small 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

wet soil
In many parts of the state, this would be a good problem to have. So let’s say you just had a rain and need to take a soil test. It would be best to wait until the soil dries but it is possible to take soil tests when soils are wet though 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 information on how to take a soil sample, see
http://www.agronomy.k-state.edu/services/soiltesting/home-owner-samples/soil-analysis/sample
-collection.html
 
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

Root competition
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 out from the shade 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 break them up. 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.
 
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)
 
Contributors: Ward Upham, Extension Associate

Video of the Week:
How to Water Succulents and Cacti

Turfgrass:
Lawn Calendar for Cool-Season Grasses

Tall Fescue lawn
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 receive enough rainfall that your turf normally 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. It must be watered in before it becomes active.
 
Late-July through August
If you see grub damage, apply a grub killer that contains Dylox. Imidacloprid is effective against young grubs and 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. Spray on a day that is at least 50 degrees. Rain or irrigate within 24 hours reduces effectiveness. Use label rates for all products! (Ward Upham)

Flowers:
Handling Tips for Valentine's Day Roses

Valentine's Rose
If you are fortunate enough to receive roses from a loved one this Valentine's Day, follow these guidelines to help extend the life of your flowers.
 
For floral arrangements:
1) Keep the vase filled or floral foam soaked with warm water. Add fresh, warm water daily. If the water turns cloudy, replace it immediately. If possible, recut stems by removing one to two inches with a sharp knife. Do this under water. This allows the stems to draw in water instead of air.
 
2) Keep flowers in a cool spot (65 to 72 degrees Fahrenheit), away from direct sunlight, heating or cooling vents, directly under ceiling fans, or near radiators.
 
3) If a rose starts to wilt, remove it from the arrangement, and recut the stem under water. Submerge the entire rose in warm water. The rose should revive in one to two hours.
 
For loose stems:
1) If you can't get your flowers in a flower food solution right away, keep them in a cool place.
2) Fill a clean, deep vase with water and add the flower food obtained from your florist. Be sure to follow the directions on the package.
 
3) Remove leaves that will be below the waterline. Leaves in water will promote bacterial growth.
 
4) Recut stems under water with a sharp knife and place the flowers in the vase solution you've prepared. (Ward Upham)

Miscellaneous:
Soil Testing

soil testing tools
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 that goes from the surface to 6 to 8 inches deep. Mix the samples together in a clean container and select about 1 pint of soil. For more detail on taking a soil test, see the K-State Dept of Agronomy instructions.
 
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 small 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

wet soil
In many parts of the state, this would be a good problem to have. So let’s say you just had a rain and need to take a soil test. It would be best to wait until the soil dries but it is possible to take soil tests when soils are wet though 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 information on how to take a soil sample, see
http://www.agronomy.k-state.edu/services/soiltesting/home-owner-samples/soil-analysis/sample
-collection.html
 
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

Root competition
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 out from the shade 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 break them up. 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.
 
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)
 
Contributors: Ward Upham, Extension Associate

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