Warm Air, Cool Soil

Warm air temperatures build anticipation of plant growth but keep in mind that cool soil temperatures will strongly moderate growth during the spring. Turf growth typically will be very slow until soil temperatures exceed 50 °F throughout most of the day. Thus, N fertilizer applied to cool soils will not stimulate a lot of growth until the soil temperatures warm. Similarly, it will take a long time to germinate seed and have seedlings emergence during early spring.

Soil temperatures at the 2-inch depth of turf plots in New Brunswick are rising in response to recent warm weather. Other than during the warmest days, temperatures still remained below 50 degrees F.

 

 

 

 

 

 

 

Useful practices at this time of year are cleaning up debris such as tree limbs, twigs and leaves that could smother turf and interfere with mowing once the grass begins to grow. You can also remove dried, desiccated leaf tissue with mowing and/or vertical mowing if you would like hasten green-up of the turf. But be cautious regarding how much you open up the turf canopy, removing too much leaf tissue could expose weed seed to sunlight and trigger germination of that seed.

If a lot of turf growth needs to be forced, covering with one or two layers of permeable growth blanket is useful. See below, an area of greener leaf growth under an area previously covered with two layers of a growth blanket. Growth blankets trap heat during sunny days, encouraging growth.

Turf growth can be “forced” during late winter and early spring by covering with a permeable growth blanket.

 

 

 

 

 

 

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