JoAnne Skelly: Climate change lengthens growing season

I never thought I would live in one place long enough to witness climate change firsthand. But, after 36 years in west Washoe Valley, I can say that the growing season has gotten longer.

When I first moved here, and for at least 25 years afterward, it wasn’t safe to plant cold-sensitive crops until after June 1, even though the average last frost date was supposed to be May 15.

Sometimes that June planting date is still the case, but with judicious covering of crops, I can usually plant here in mid- to late May now. On the other end of the season, I could count on multiple freezes in August, often forcing me to bring all the green tomatoes indoors to ripen. Now, it seems that the average first frost date has moved almost to Oct. 1 from the old Sept. 15 date for folks in town.

On the whole, I think many long-time gardeners might agree with me that the season is longer. However, this is Northern Nevada and if you wait five minutes the weather will change. By that I mean, don’t count on a longer growing season. At this time of year, watch the weather every night to see if you have to cover your cold sensitive crops. I keep lots of old flannel sheets and blankets for this purpose. Plastic acts as a conductor of cold, so I avoid using it for cold protection.

A good indicator that a freeze is likely is if the sky is clear, there is no wind in the evening, and the meteorologist is reporting weather in the mid- to upper 30s. If you value your veggies, you may want to cover them that night.

Use the USDA Plant Zone map to discover the average winter low in your zip code (https://planthardiness.ars.usda.gov/). This map says the average low for my zip code, 89704, as well 89701 and 89410, is 0 degrees to 5 degrees Fahrenheit.

Some areas may be warmer. I doubt I will plant anything now, but if you want to try, transplants will work better than seed.

Here are cold hardy crops with their lowest temperature tolerated in parenthesis: kales (20), lettuce (25), spinach (15-20), arugula (20), chives (perennial), collards (10-20), carrots (5-15), beets (20), Brussel sprouts (20) cilantro (20), parsley (20), parsnips (5), mustard greens (20), radishes (20), leeks (5), turnips (25).

Cold tolerance can vary by variety and microclimate. If you mulch plants heavily, that should help protect them and keep the soil warmer. Row covers can be protective as well.

JoAnne Skelly is Associate Professor & Extension Educator Emerita at University of Nevada Cooperative Extension. Reach her at skellyj@unr.edu.