"grass frost"?

[caroline7758]

I'm sure I just heard the weather man on GQT say there might be a "grass frost" tonight. Is this the same as a ground frost? Or do I need my ears washing out?

[caroline7758]

[Baccy Man]

In spring and early summer, when the temperature is expected to produce a frost using the grass minimum thermometer, but not over other surfaces (due to thermal inertia of surfaces such as concrete, tarmac etc.), then the unofficial term 'grass-frost' may be used in weather forecasts - this is to try and avoid panic by road, railway and airport operators as soon as they hear the word 'frost' but alert gardeners, growers etc., to the risk of damage.
So essentially it is a mild ground frost.

[caroline7758]

So should I cover my pots with annuals in?

[tim]

-1C here - so Cus & Courgettes covered!