Ask an Expert: Spring Has Sprung, but Frost Still Likely

    Ask an Expert: Spring Has Sprung, but Frost Still Likely

    FrostDetermining when to plant a garden can be especially confusing in Utah’s unpredictable, varied climate where last-frost dates can vary by many days within just a few miles. Many experienced gardeners have planted and later lost their plants to frost.

    An example of how fickle Utah’s climate can be is in Cache Valley. Frost-free days vary from an average of 113 days in Lewiston and Trenton to 158 days on the USU campus. Similar examples are common around the state.

    Geographic characteristics of where you live can help in determining when to plant. When a yard is located in a populated area or on a mountain bench, it usually has a longer growing season. Other areas located at slightly lower elevations where cold air drains and cannot escape have a shorter season. This is why local commercial orchards are generally located on benches. Additionally, urban and suburban areas are slightly warmer than surrounding areas due to the urban heat effect. Heat from buildings and warmth generated by sunlight reflected from roads and other surfaces increases temperatures and delays frost. It can be helpful to chat with a local farmer or experienced gardener in your area to determine what works for him or her regarding when to plant.

    In addition to frost information, it is important to take into account the needs of the plants. Vegetables planted locally fall into four basic categories: hardy, semi-hardy, tender and very tender. Depending on which category a plant belongs to, planting dates vary from early spring until early summer. Consider the following:

    • Hardy vegetables, including asparagus, broccoli, cabbage, onions, peas and spinach, can be planted as soon as the soil is workable in early spring. This usually ranges between 45 and 60 days before the average last frost. These same vegetables can be safely planted until the average last frost date.
    • Semi-hardy plants, such as beets, carrots, lettuce and potatoes, can be planted one to two weeks after the hardy group. These can be planted until the average last-frost date.
    • Tender vegetables, such as celery, cucumbers, corn and most beans, should be planted on the average last-frost date. 
    • Very tender plants, such as squash, beans, melons, tomatoes, eggplants and peppers, should not be planted until at least a week after the average last frost. Even if frost does not occur before this time, these plants will not grow well and are more susceptible to disease until warmer weather. 

    If you have lost plants to frost, you are not alone, and all you can do is try again.

     

    Average Frost Dates for Various Utah Locations (Note that these dates are averages and can vary from year to year.)

     

                 Frost Dates

     

    City

    Last

    First

    Frost-Free Days

    Alpine

    May 20

    September 30

    136

    Blanding

    May 13

    October 12

    153

    Cedar City

    May 10

    October 5

    148

    Delta

    May 17

    September 28

    134

    Farmington

    May 5

    October 10

    158

    Fillmore

    May 16

    October 4

    140

    Huntsville

    June 11

    September 9

      89

    Kanab

    May 7

    October 20

    166

    Lake Town

    June 15

    September 10

      87

    Logan

    May 14

    September 25

    135

    Morgan

    June 6

    September 11

     98

    Moroni

    June 1

    September 18

    109

    Ogden

    May 1

    October 24

    176

    Park City

    June 9

    September 1

      92

    Price

    May 12

    October 7

    148

    Roosevelt

    May 18

    September 25

    130

    Spanish Fork

    May 1

    October 13

    165

    St. George

    April 6

    October 28

    205

    Tooele

    May 7

    October 14

    159

    Tremonton

    May 3

    October 10

    160

     

    By: Taun Beddes, Utah State University Extension horticulturist, 801-851-8460, taun.beddes@usu.edu
    Published on: May 03, 2016

    Related Articles

    Ask an Expert: When to Plant? That is the Question

    Ask an Expert: When to Plant? That is the Question

    Determining when to plant a garden can be especially confusing in Utah's unpredictable, varied climate where last-frost dates can vary by many days within just a few miles. Many experienced gardeners have planted and later lost their plants to frost.

    Read More
    Ask an Expert: Slithering Snakes Spotted in Parks and Lawns

    Ask an Expert: Slithering Snakes Spotted in Parks and Lawns

    Just in time for Halloween, an increased number of snakes have recently been reported in lawns, golf courses and city parks. Aside from callers being spooked by an unexpected encounter with a snake, they are also concerned about the snakes harming them, their children or taking up residence in their homes.

    Read More
    There's a New Pest in Town

    There's a New Pest in Town

    The elm seed bug has been recognized as Utah's newest pest. It was first discovered in Utah in July 2014 and confirmed by the Utah State University Extension Utah Plant Pest Diagnostic Lab and the U.S. Department of Agriculture, Animal and Plant Health Inspection Service. The elm seed bug has now been widely reported along the Wasatch Front, Cache County, east to Duchesne County, west to Tooele County and south to Grand County.

    Read More