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 8. 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 10, so we don't dare plant that early. We wait a few days and by May 21 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.
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
Last 16° | Apr 13 | Apr 8 | Apr 4 | Apr 1 | Mar 29 | Mar 26 | Mar 23 | Mar 19 | Mar 14 |
Last 20° | Apr 17 | Apr 13 | Apr 10 | Apr 7 | Apr 5 | Apr 2 | Mar 31 | Mar 28 | Mar 23 |
Last 24° | Apr 28 | Apr 23 | Apr 19 | Apr 16 | Apr 14 | Apr 11 | Apr 8 | Apr 4 | Mar 31 |
Last 28° | May 8 | May 4 | May 1 | Apr 28 | Apr 26 | Apr 23 | Apr 21 | Apr 18 | Apr 14 |
Last 32° | May 22 | May 17 | May 13 | May 10 | May 7 | May 4 | May 1 | Apr 28 | Apr 23 |
Last 36° | Jun 8 | Jun 2 | May 29 | May 25 | May 21 | May 18 | May 14 | May 10 | May 4 |
The charts on this page show the probabilities of receiving a certain temperature on a certain day. Some examples that might help:
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
First 16° | Oct 28 | Nov 1 | Nov 5 | Nov 8 | Nov 10 | Nov 13 | Nov 16 | Nov 19 | Nov 24 |
First 20° | Oct 16 | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 3 | Nov 7 | Nov 10 | Nov 16 |
First 24° | Oct 5 | Oct 11 | Oct 15 | Oct 18 | Oct 21 | Oct 25 | Oct 28 | Nov 1 | Nov 7 |
First 28° | Sep 25 | Sep 30 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 24 |
First 32° | Sep 13 | Sep 18 | Sep 21 | Sep 24 | Sep 27 | Sep 29 | Oct 2 | Oct 5 | Oct 10 |
First 36° | Sep 11 | Sep 15 | Sep 18 | Sep 21 | Sep 23 | Sep 25 | Sep 28 | Oct 1 | Oct 5 |
Now that you know your frost dates, use our Garden Planting Calendar for Faribault, MN to know when to sow and transplant your various vegetable plants!
Data is provided by the NOAA National Centers for Environmental Information. Photography by Garden.org member TBGDN.