November 2009, Volume 12, Issue 5
Jacklin Seed Research News Flash
Selected and adapted excerpts
Is there some way of predicting how long grass will take to germinate in the spring, especially when temperatures are cold ?
There are a few research studies that address this issue, mainly by Danish authors.
An article by Søren Ugilt Larsen and Bo Martin Bibby allows you to predict when in the spring Kentucky bluegrass will germinate, given daily air temperature.
The trick is to keep a running tally of all the daily maximum temperatures above 2.6°C ( or 37°F ).
If you take your daily high, subtract 2.6 °C ( or 37°F ), your Kentucky bluegrass will reach 50 per cent germination when the running sum exceeds 115°C ( 207°F ) cumulative degrees.
Thermal time for perennial ryegrass is 63.9 C ( 115°F ), and 43.8°C ( 79°F ) for red fescue.
An older but still relevant article comes from a 1940 USGA publication by Aubrey W. Naylor.
Naylor explains that mature Kentucky bluegrass grows in the spring long before its seed would germinate.
Bluegrass ― when well-established, grows most vigorously at temperatures between 60° and 75°F.
Kentucky bluegrass, once it has become established, will grow well under conditions which are unfavorable for the germination of its seed and for early growth.
Classification Of Turfgrasses According To Their
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Turfgrass species |
Seed germination rate |
Seed establishment rate |
Optimal germination |
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|
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Annual bluegrass
|
Moderately fast |
Moderately slow |
20 to 30°C |
Annual ryegrass
|
Very fast |
Very fast |
20 to 30°C |
Canada bluegrass
|
Moderately slow |
Slow |
— |
Chewings fescue
|
Moderately fast |
Moderately fast |
20 to 25°C |
Colonial bentgrass
|
Moderately fast |
Moderately slow |
15 to 30°C |
Creeping bentgrass
|
Fast |
Moderately slow |
15 to 30°C |
Creeping bluegrass
|
Fast |
Moderately slow |
— |
Hard fescue
|
Moderately fast |
Moderately fast |
— |
Kentucky bluegrass, |
Moderately slow |
Slow |
15 to 30°C |
Kentucky bluegrass, |
Moderately fast |
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Perennial ryegrass
|
Fast |
Fast |
20 to 30°C |
Red fescue
|
Moderately fast |
Moderately fast |
15 to 30°C |
Red top
|
Moderately fast |
Fast |
20 to 30°C |
Rough bluegrass
|
Moderately slow |
Slow |
20 to 30°C |
Sheep fescue
|
Moderately fast |
Moderately fast |
— |
Tall fescue
|
Moderately fast |
Moderately fast |
20 to 30°C |
Establishment rates are an estimated measure of the time required for seedlings to develop, under optimal conditions, into mature and healthy plants that are « ready-for-use ». The optimal conditions for the seed germination of most species may not require a single temperature, but a rhythmic alternation of temperature. In the above table, the first number indicates the initial temperature that must be maintained for approximately sixteen hours. The second number indicates the following temperature that must be maintained for approximately eight hours. ( Beard, 1973 )
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For a copy of the original A Look At Report, go to the following link …
NORAHG has archived more information about TURF & ORNAMENTALS, and other topics, on The Pesticide Truths Web-Site …
A LOOK AT … REFERENCES & SLIDE SHOWS – TURF, ORNAMENTALS, ENVIRONMENT, & MAINTENANCE
https://pesticidetruths.com/toc/a-look-at-references-turf-ornamentals/
A LOOK AT … REPORTS – TURF, ORNAMENTALS, & MAINTENANCE
https://pesticidetruths.com/toc/a-look-at-reports/
A LOOK AT … CAREER MANAGEMENT
https://pesticidetruths.com/toc/a-look-at-career-management/
UPDATES & WARNINGS
https://pesticidetruths.com/toc/updates-warning/
THE WISDOM OF ART C. DRYSDALE
https://pesticidetruths.com/toc/the-wisdom-of-art-c-drysdale/