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 17. 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 22 | Mar 14 | Mar 9 | Mar 4 | Feb 28 | Feb 23 | Feb 18 | Feb 13 | Feb 5 |
Last 20° | Apr 3 | Mar 28 | Mar 23 | Mar 19 | Mar 15 | Mar 11 | Mar 7 | Mar 2 | Feb 23 |
Last 24° | Apr 13 | Apr 7 | Apr 3 | Mar 31 | Mar 27 | Mar 24 | Mar 20 | Mar 16 | Mar 11 |
Last 28° | Apr 24 | Apr 19 | Apr 15 | Apr 12 | Apr 9 | Apr 7 | Apr 4 | Mar 31 | Mar 26 |
Last 32° | May 3 | Apr 29 | Apr 26 | Apr 23 | Apr 21 | Apr 18 | Apr 16 | Apr 13 | Apr 8 |
Last 36° | May 17 | May 12 | May 8 | May 5 | May 3 | Apr 30 | Apr 27 | Apr 23 | Apr 18 |
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 11 | Nov 21 | Nov 29 | Dec 5 | Dec 11 | Dec 17 | Dec 23 | Dec 30 | Jan 10 |
First 20° | Nov 7 | Nov 12 | Nov 15 | Nov 19 | Nov 22 | Nov 25 | Nov 28 | Dec 1 | Dec 7 |
First 24° | Oct 23 | Oct 29 | Nov 2 | Nov 5 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 25 |
First 28° | Oct 10 | Oct 16 | Oct 21 | Oct 25 | Oct 29 | Nov 1 | Nov 5 | Nov 10 | Nov 16 |
First 32° | Oct 5 | Oct 9 | Oct 12 | Oct 15 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 30 |
First 36° | Sep 27 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 11 | Oct 13 | Oct 16 | Oct 20 |
Now that you know your frost dates, use our Garden Planting Calendar for Bremo Bluff, 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.