FROST
WARNINGS
Frost warnings,
issued near the
beginning of the summer growing season, keep gardeners on their toes.
Since everyone likes to get a head start on the summer garden
(perhaps for bragging rights to 'the first tomato') they plant
their
tomatoes and annual flowers as early as possible. Unfortunately,
many of these tender plants will be severely damaged or killed by a
late frost.
Frost is more likely to occur in low-lying areas due to the
pooling of cold air close to the ground. Therefore, even when there
is
frost damage in valley gardens, ridge top gardens might be spared. This is one
reason fruit growers attempt to locate their orchards in higher
locations, so the tender flowers that will someday be fruit, aren't as
likely to be 'nipped' by a late frost.
PROTECTING AGAINST FROST DAMAGE
The best defense against frost is not planting too early in the
growing season. The rule of thumb in northeastern gardens is to
plant tender annuals and vegetable plants on or after Memorial Day.
Our best prediction for the last average spring frost in the Pittsburgh
area is May 20th. However, during some years annuals could have been planted
May 1st without suffering frost damage, while other years a late frost at
the end of May could have wiped out tender plants.
Heavy frost is most likely to occur on those cold, clear nights when
the stars are bright and there isn't a 'blanket' of cloud cover to
hold heat close to the earth. Most weather services will issue Frost
Warnings, but it's best to be alert and pro-active if you've
planted early, or wish to spare your landscape plants from damage.
In order to cheat nature a bit and get plants in early, there are
a few products available that will help, such as row covers and other
inventions, that keep heat close to plants and frost away. The most
basic way to protect plants in your home landscape is by covering
them with a cloth tarp. We've found 10 ft x 10 ft leaf tarps
work very well (synthetic burlap). Something like an old bed sheet or pillow case will
also work, provided they are light weight and don't break the plant under
their weight. Burlap works well also, but must be thoroughly dried
before storage. Hanging baskets and potted plants can be moved under
a patio roof, or in the event of freezing temperatures, moved inside
a garage or house.
Commercial nurserymen often use "frost blankets" to protect their
nursery stock during spring cold spells. Trees are laid down and
grouped together in a row, then the row is covered with a
lightweight, white, synthetic material that resembles landscape
fabric. All the edges must be firmly secured with weight (rocks,
other potted plants) to prevent the wind from getting under the
cover and removing it.
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