DENVER — You've probably heard the old weather adage on the Front Range: "Don't plant tomatoes until after Mother's Day." Well, a freeze doesn't appear to be likely, but there's just enough unsettled weather ahead to wait until the weekend after. That goes for all tomatoes, peppers and other cold-sensitive veggies.
There’s a good chance that the last freeze of the season below 6,000 feet happened on Wednesday morning. Only a few spots dropped below freezing in the Denver metro, and most of those were in the south or west suburbs.
This might tempt you to plant sensitive veggies like tomatoes and peppers outside in your garden on Mother’s Day weekend. But before you do, let's look at the extended forecast.
Looking at the 14-day computer model ensemble forecast for high and low temperatures in Denver doesn't reveal anything too concerning in the way of a frost all the way through May 22. Computer models can't predict the exact temperature 14 days in advance, but this product is good at revealing trends and sending up early red flags.
In Denver, a freeze after May 22 has only happened seven times in 152 years, the latest being June 8, 2007.
However, there doesn’t have to be a frost for plants to be harmed. The low-temperature forecast for the five days after Mother’s Day is not exactly the forecast that newly planted tomatoes are going to want to see. Overnight lows below 45 degrees won’t kill the plants, but it could slow their development significantly.
In the jet stream forecast, there is a cold Canadian trough showing around May 15-16. That could end up being close enough to drop overnight temperatures in the Denver area below 40 degrees a few times after Mother’s Day. Troughs in that position are famous for sending backdoor cold fronts onto the Front Range, trapping the cold up against the foothills.
So, even though a widespread hard freeze in the Denver metro area is very unlikely at this point, the safest move would be to wait for the weekend after Mother’s Day to plant these sensitive vegetables outside — as usual.
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