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 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 April 17, so we don't dare plant that early. We wait a few days and by April 25 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 24 | Mar 17 | Mar 12 | Mar 7 | Mar 3 | Feb 27 | Feb 22 | Feb 17 | Feb 10 |
Last 20° | Apr 3 | Mar 28 | Mar 23 | Mar 20 | Mar 16 | Mar 13 | Mar 9 | Mar 5 | Feb 27 |
Last 24° | Apr 8 | Apr 4 | Mar 31 | Mar 29 | Mar 26 | Mar 23 | Mar 21 | Mar 17 | Mar 13 |
Last 28° | Apr 15 | Apr 11 | Apr 8 | Apr 5 | Apr 3 | Apr 1 | Mar 29 | Mar 26 | Mar 22 |
Last 32° | Apr 28 | Apr 24 | Apr 21 | Apr 18 | Apr 16 | Apr 14 | Apr 11 | Apr 8 | Apr 4 |
Last 36° | May 8 | May 3 | Apr 30 | Apr 28 | Apr 25 | Apr 23 | Apr 20 | Apr 17 | Apr 13 |
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 28 | Dec 3 | Dec 7 | Dec 10 | Dec 14 | Dec 17 | Dec 20 | Dec 24 | Dec 29 |
First 20° | Nov 17 | Nov 23 | Nov 27 | Dec 1 | Dec 4 | Dec 8 | Dec 11 | Dec 15 | Dec 21 |
First 24° | Nov 3 | Nov 9 | Nov 13 | Nov 17 | Nov 20 | Nov 23 | Nov 27 | Dec 1 | Dec 7 |
First 28° | Oct 24 | Oct 30 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 24 |
First 32° | Oct 16 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 2 | Nov 5 | Nov 9 | Nov 14 |
First 36° | Oct 1 | Oct 6 | Oct 10 | Oct 13 | Oct 16 | Oct 18 | Oct 21 | Oct 25 | Oct 30 |
Now that you know your frost dates, use our Garden Planting Calendar for Sandusky, OH 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.