A frost or freeze in Spring gardens can be devastating!
The month of May can lull gardeners into a false sense of security when it comes to outdoor plants in the northeastern United States.
Even though weather has begun to warm-up nicely in May (most nights stay above 40-degrees F.) there can still be a night or two when temperatures drop into the low-30's and cause severe damage to the tender new growth on landscape plants and freshly planted annual flowers and vegetable plants in the garden.
Cold damage showed up as brown leaves on this Laceleaf Japanese Maple two weeks after a couple cold nights in mid-May
Some plants are more susceptible to cold damage than others. Ornamental plants like the Laceleaf Japanese Maple in the photo above are particularly sensitive to late spring cold snaps. It can be like the old one-two knockout punch If new buds and leaves get hit hard twice in the Spring!
These are typically the nights
when the sky is clear,
with no cloud cover
to hold the Earth's warmth.
Therefore, it is best to throw a bed sheet over top of these sensitive plants when they have already leafed-out and you hear a cold night is in the weather forecast. You can also use several pages of newspaper to cover plants but plastic is not recommended. Plants in pots can be moved under cover or inside.
This unpredictable cold during the month of May is one reason many gardeners wait until Memorial Day to plant frost-sensitive plants like tomatoes.