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