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