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