temperature

Last week I wrote about some calculations to find the inflection point when the temperatures change from being better for warm-season grass (like bermudagrass, seashore paspalum, or zoysia) to being better for cool-season grasses (like perennial ryegrass, creeping bentgrass, or kentucky bluegrass).

The turfgrass growth potential (GP) is a number that represents the proximity of the actual temperature to the optimum temperatures for growth. GP is used for a lot of things. One can use it to make estimates of nutrient use, estimates of topdressing amounts, and to find the time in autumn when the cool-season growth potential starts to exceed the warm-season growth potential.

Every now and then I get some questions about the temperature-based growth potential (GP). The most recent question was about relative humidity: “I am curious about the effect relative humidity has on growth potential?

I was wondering what the effect was. I expected a 1 or 2 °C decrease in nighttime soil temperature in drier soils, compared to soils with more water. I didn’t find it.

I think temperature has more of an influence on turf growth, and I will use some data from Iceland to show why. This concerns the situation when there is not shade from buildings or trees, and looks at a situation when the light is more than sufficient for growth, but the grass does not grow.

Here’s a mystery about green patterns in straight lines on greens in Iceland. This is Iceland in early May. There was still snow on the mountains around Reykjavik. The greens in question are primarily fine fescue.

Every turf manager knows that temperature has a huge influence on the growth rate of the grass. Consequently, mowing, fertilizing, overseeding, winter dormancy, heat stress of cool season grasses, and much more are all directly influenced by temperature.

I had thought the fans in the tea fields of Shizuoka were used to reduce fungal diseases of the foliage during hot and humid weather. I’ve learned that the actual reason for these fans is to prevent frost from forming on the leaves during winter, by blowing warmer air (cold air is heavier, and sinks) down to the plants.

This fact sheet provides an overview of the turfgrass growth potential (GP), explaining what it is, how it is calculated, providing examples of estimated plant nitrogen use based on GP, and much more, including suggestions on how the GP can be modified and extended.