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