The charts on this page show the probabilities of receiving a certain temperature on a certain day. Some examples that might help:
|First 16°||Oct 27||Nov 1||Nov 4||Nov 7||Nov 10||Nov 13||Nov 16||Nov 20||Nov 25|
|First 20°||Oct 16||Oct 22||Oct 25||Oct 28||Oct 31||Nov 3||Nov 7||Nov 10||Nov 15|
|First 24°||Oct 8||Oct 13||Oct 17||Oct 21||Oct 24||Oct 27||Oct 31||Nov 4||Nov 9|
|First 28°||Sep 25||Sep 30||Oct 4||Oct 7||Oct 10||Oct 13||Oct 17||Oct 20||Oct 26|
|First 32°||Sep 19||Sep 24||Sep 27||Sep 30||Oct 2||Oct 5||Oct 8||Oct 11||Oct 15|
|First 36°||Sep 13||Sep 16||Sep 18||Sep 20||Sep 22||Sep 24||Sep 26||Sep 28||Oct 2|
What's a safe temperature for tender plants? When the nightly temperature falls, frost can form, even above 32°, because the air is colder high above the ground and the frost can form up there and then fall down onto your garden and do some damage, even if it's 36° on the ground. So many factors come into play, including wind, concrete, houses, trees and other structures, etc etc etc. Because of all this, you might want to consider 36° as "the danger zone".
In your average springtime, you have a 90% chance that there will be no 36° nights by June 2. In other words, you can pretty much count on being safe from frost by that day. But we want to get those tomatoes in the ground as soon as possible, right? We see that there's still an 80% chance of 36° on May 4, so we don't dare plant that early. We wait a few days and by May 15 we are at the 50/50 point. At this point, we are close and we can start watching the weather forecast. If the upcoming week's forecast doesn't show below 40°, then it's probably okay to risk planting out your plants. If conditions change and a surprise frost does threaten, there's always things you can do to protect plants from frost.
|Last 16°||Apr 11||Apr 5||Apr 2||Mar 29||Mar 27||Mar 24||Mar 20||Mar 17||Mar 11|
|Last 20°||Apr 16||Apr 11||Apr 8||Apr 5||Apr 2||Mar 30||Mar 27||Mar 24||Mar 19|
|Last 24°||Apr 21||Apr 17||Apr 13||Apr 11||Apr 8||Apr 5||Apr 3||Mar 30||Mar 26|
|Last 28°||May 4||Apr 29||Apr 25||Apr 21||Apr 18||Apr 14||Apr 11||Apr 7||Apr 1|
|Last 32°||May 16||May 11||May 8||May 6||May 3||Apr 30||Apr 28||Apr 25||Apr 20|
|Last 36°||Jun 2||May 27||May 22||May 19||May 15||May 12||May 8||May 4||Apr 28|
Now that you know your frost dates, use our Garden Planting Calendar for Rochester, Minnesota to know when to sow and transplant your various vegetable plants!