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 May 20. 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 April 24, so we don't dare plant that early. We wait a few days and by May 4 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° | Mar 20 | Mar 14 | Mar 10 | Mar 6 | Mar 2 | Feb 27 | Feb 23 | Feb 19 | Feb 13 |
Last 20° | Apr 3 | Mar 28 | Mar 24 | Mar 20 | Mar 17 | Mar 13 | Mar 10 | Mar 6 | Feb 28 |
Last 24° | Apr 15 | Apr 11 | Apr 8 | Apr 5 | Apr 2 | Mar 31 | Mar 28 | Mar 25 | Mar 21 |
Last 28° | Apr 27 | Apr 21 | Apr 17 | Apr 14 | Apr 11 | Apr 8 | Apr 5 | Apr 1 | Mar 27 |
Last 32° | May 9 | May 4 | May 1 | Apr 28 | Apr 25 | Apr 22 | Apr 19 | Apr 15 | Apr 11 |
Last 36° | May 20 | May 14 | May 11 | May 7 | May 4 | May 1 | Apr 28 | Apr 24 | Apr 19 |
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° | Nov 13 | Nov 21 | Nov 26 | Dec 1 | Dec 5 | Dec 9 | Dec 14 | Dec 20 | Dec 27 |
First 20° | Oct 29 | Nov 6 | Nov 11 | Nov 16 | Nov 20 | Nov 25 | Nov 29 | Dec 5 | Dec 12 |
First 24° | Oct 21 | Oct 26 | Oct 30 | Nov 2 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 21 |
First 28° | Oct 8 | Oct 15 | Oct 19 | Oct 23 | Oct 27 | Oct 30 | Nov 3 | Nov 8 | Nov 14 |
First 32° | Sep 28 | Oct 3 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 20 | Oct 23 | Oct 29 |
First 36° | Sep 23 | Sep 27 | Sep 30 | Oct 3 | Oct 5 | Oct 7 | Oct 10 | Oct 13 | Oct 17 |
Now that you know your frost dates, use our Garden Planting Calendar for Loveland, Ohio 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.