When To Plant?

I get many questions just like this one that came in this morning…

“When will it finally be safe to start planting flowers and doing landscaping projects without fear of cold temps killing the plants at night? A rough estimate is fine.”

First off, there isn’t much skill in a specific forecast beyond seven days, but there is some skill at pattern recognition and thoughts on possible weather out to 16 days.

NEXT SEVEN DAYS: We are looking at lows in the mid 30s early Monday of next week, and that would mean a potential freeze for the colder valleys across the northern half of Alabama. That is the only morning with some freeze possibilities during our forecast period.

LONG RANGE: Let’s talk statistics… the information below is for Birmingham, based on weather records from 1895-2010:

Earliest last freeze – February 3rd, 1945
Average date of last Spring freeze – March 26th
Latest Spring freezing temperature – April 23rd, 1986
Earliest Autumn freezing temperature – October 18th, 1948
Average date of first Autumn freeze – November 9th
Latest first freeze – January 10th, 1932

So, the average date of the last Spring freeze is March 26; nine days away. Needless to say, it is too early to plant anything now that could be harmed by freezing temperatures. And, you can see we have had a freeze as late as April 23.

Based on the projected Arctic Oscillation, which stays negative into mid-April, we have to figure we will have on or two freeze threats perhaps into early April (see the bottom chart below)…

BOTTOM LINE: If you want to be perfectly safe, wait until April 15. However, I would suggest odds are pretty good you will be safe from a freeze beginning April 10. But, understand there are no guarantees in the weather business!

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