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Total Landscape Management

Early Spring Planting-What Plants Can Withstand a Late Frost?

It is March and definitely time to start planning your spring garden. Utah’s weather can be unpredictable, and it can vary in temperature from area to area. Did you know that urban and suburban areas have a slightly longer growing season in Utah than rural areas? It’s the reflected heat from roads and building that keep things warmer longer. Did you know that benches surprisingly have longer growing seasons than the lowest valley elevations? Cold air can get trapped in lower parts of the valley, shorting its growing season.

The best way to plan for your garden is to know your area and its projected frost free days. In Salt Lake County, most people expect frost to be done by Mother’s Day. That’s a day that’s easy to remember and shoot for. On average, Utah’s growing season is May 15-October 25, but that’s the average. If you want more precise information about your area, you can call the Utah State University extension office for Salt Lake County (385) 468-4820.

When planning your garden, you can predict which plants can withstand the most cold and late frosts. Did you know that plants are rated for how well they withstand cold temperatures? Knowing your plants’ hardiness rating can help you decide what to plant and when.

Hardy plants can be planted as soon as the ground is thawed and is workable, probably by around April 3. Another option is that you can start growing them indoors now and then transplant them outside by the end of April. These plants include the following:

  • Broccoli
  • Cauliflower
  • Cabbage
  • Peas
  • Spinach

Semi-hardy plants can be planted outside about mid-April. They are a few weeks behind hardy veggies. They include the following:

  • Beets
  • Carrots
  • Lettuce
  • Potatoes
  • Onions

Tender plants can be planted outside after the last frost date, so close to Mother’s Day. They include the following:

  • Celery
  • Cucumber
  • Corn
  • Beans

Very tender plants are the most delicate and easily killed by frost. They should be planted a week after the last frost date, so to be safe, the third week of May. Remember, you can always start plants like tomatoes and peppers indoors in March and then transplant them. Very tender plants include the following:

  • Squash
  • Melons
  • Tomatoes,
  • Eggplants
  • Peppers

Following this calendar is the safest way to help most or all of your plants survive. Undoubtedly, in April we are going to have some warm days. Some of us may even turn on our A/C. It may seem silly to wait to plant the tender and very tender plants until mid-May. But know that these dates are based on average temperatures that have been recorded for many years. You can generally trust these dates. However, nothing is a guarantee. There have been some late frosts recorded as late as the last week of May.

In Salt Lake City, you never know what weather you are going to get. It could be sunny enough for lawn maintenance one minute and freezing rain the next. So watch the weather forecasts, and do you best. If you happen to lose some tender plants due to a late frost, know that you haven’t lost everything. You can replant the ones you lost. It’s easy to find starts at your local garden center.