The map
above is based on average dates when you can
begin setting out plants without fear of frost in the U.S
and Canada.
Many
old garden hands in Mid-Atlantic states, for example, will
tell you that the first day for outdoor spring planting
is actually April 20, when they will set out frost-resitant
varieties of vegetables (peas,
radishes)
before planting warm weather crops and flowers nearer the
end of the month.
In
short, use the map as a guideline only, and if you are still
unsure of the safe frost-free date in your area, take adventage
of local garden wisdom by asking knowledgeable neighbors
when they begin planting their spring gardens.
Climate
is what we expect, weather is what we get.
Mark Twain
More
Frost Free Dates:
U.S.
Spring Freeze Occurence
The
Atlas of Canada - Last Frost in Spring
UK
First & Last Frost Dates