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