Gardeners who scrambled on Monday to protect new plants from a predicted overnight frost will have to repeat the chore on Tuesday night.

The Twin Cities can expect a second consecutive night below freezing -- Monday night's was the first freezing temperature since March 9 -- and temperatures across much of southern and central Minnesota are expected to dip to the mid-20s.

Carol Hejl at the landscape project desk at Gerten's Greenhouses and Garden Center in Inver Grove Heights said gardeners who "jumped the gun" and planted new annual plants or even perennials, or have early-season green vegetables already sprouting, should cover them with a sheet or bring them into a garage or other shelter.

Tulips and other perennials should be fine, she said, although even cool-weather pansies ought to be protected.

She said Mother's Day remains the traditional date by which new plants can survive outside, but the extreme warmth of recent weeks has had many people thinking May arrived weeks ago.

The forecast calls for a slow warmup into the weekend after Tuesday night.

The average date of the final 28-degree reading of the season in the Twin Cities is April 16; in Cambridge, Minn., it's April 30. The final 32-degree experience in the Twin Cities is April 29, on average, and in Cambridge May 9.