MCC Daily Tribune Archive

Frost Warning


Unusual circumstance, but it has happened before here in the Rochester area. Historically we have always told folks wait until May 31 to plant frost-sensitive stuff.

Well, if it’s going to be mid 30s for the Rochester area, there is a good chance we will get critical cold temperatures for nearby areas, i.e. west Rush.  If we get cloud cover during the coldest time during the night, that should help keep frost to a minimum (usually above 28).  But if it clears, then it will dip to create damage to growth tips and blossoms on plants. Most tree fruits are done with blossom but strawberries are still blooming.  If it gets lower then 27 then there will be significant damage.  When temps get to 24 or lower, then its severe damage, usually unrecoverable crops.

Hoar (type) frost can kill a plant by initiating the freezing of the water inside the plant cells. 

Many types of dark colored soils are better at absorbing light that light colored soils during the day.  Consequently dark colored soils can store more heat and not be as prone to frost.

Don’t cultivate when a frost threatens.  A loose, cultivated field insulates the soil and prevents heat movement from the soil to the air and around the plants.  A more compacted soil will actually release heat more quickly to the air, thus protecting the plants.

The use of covers – this is a good stand by and the best time to apply them would be in late afternoon when the wind has died down.

Irrigating the field with sprinklers will also work. As the water freezes heat is released as long as ice is being formed.   However, once you start irrigating you cannot stop irrigating until the next morning when the sun is on the crop and the ice loosens.

For crops like field corn and sweet corn, the growth tip is well protected and will be ok.  Cabbage, broccoli, cauliflower, celery, peas, lettuce, spinach, and onions should be ok.

If you have potatoes or sweet potatoes and they are sprouting, just put some soil over the sprouts to protect them.

Most annuals, seedlings,  tender perennials  (i.e. zonal geraniums), and tender vegetables such as tomatoes, snap beans, sweet potato, pepper, cucumber, watermelon, muskmelon, lima bean, squash and pumpkin.are frost sensitive and are likely to experience cold damage if lower then 32 degrees. Protect them as best as possible. Bring them in and or cover them with blankets, buckets.

Don’t wash the frost off a plant in the morning after a frost/freeze.

Bob King
Agriculture and Life Sciences Institute
05/28/2008