As overnight temperatures dip below freezing, some farmers in San Luis Obispo County are taking steps to protect their crops from the frost.

At the Dragon Spring Farm on Santa Rosa Creek Road near Cambria, Mike and Carol Broadhurst grow a variety of produce, including avocados, citrus and an acre of blueberries. In order to prevent the loss of the blueberry crop, the couple has covered four rows of berries and deployed smudge pots.

“We go out at 2 or 3 in the morning to light them,” Carol Broadhurst said.

The farm also grows Star Ruby grapefruit that are vulnerable to the cold. Ironically, the crops typically most vulnerable to frost — avocados and citrus — are faring well because of where they are planted, Carol said.

Those trees were planted on hillsides where they tend to be above the coldest temperatures. Cold air is denser and flows downhill so there can be as much as a 10 degree difference between the ridge tops and the two-and-half acres of bottomland on the farm.

Smudge pots and wind machines are two common tools in fighting frost. But the most important thing a farmer can do is irrigate, Carol said.

“A freeze takes a lot of water out of the plants, so you have to irrigate a lot,” she said.