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