Gardening in the Salt Lake area can be a bit challenging at first, particularly if you’ve either never gardened before or if you’ve moved to the area recently. There are a few things to keep in mind as you start gardening in Northern Utah: the climate, soil alkalinity, water alkalinity, and the relative lack of precipitation during part of the year.
One thing to check when selecting perennial plants for your garden is both your area’s hardiness zone, and the hardiness of the plants. Hardiness zones are based on the average annual lowest winter temperatures. Each zone is divided up in 10 degree F increments. For 2012, the USDA Agricultural Research Service updated the hardiness zone map and instituted an interactive map into which you can enter your zip code to find the hardiness zone for your area. You can access this map at: HTTP://PLANTHARDINESS.ARS.USDA.GOV/PHZMWEB/.
Here in the Salt Lake valley, hot and dry summers are followed by cold and snowy winters- this can be tough on many plants. In Utah, the hardiness zone varies between 4 and 6, depending on where you live. Most gardens in Salt Lake City are in zone 5 with a minimum temperature ranging from –10 to –20 degrees Fahrenheit. So, before you purchase or install your perennial plants (plants that live more than two years), check to make sure they are going to survive in your area- make sure their listed hardiness is at or lower than your area’s hardiness zone.
The average last frost date in spring is May 7 and the first frost of the year is usually around October 17. If you’re accustomed to a warmer climate and you want to grow plants zone 7 or above, treat them as annuals, or plan on overwintering them inside. For marginal plants (those slightly higher in zone than your area), plan on mulching them well in the fall or plant them close to the foundation of a heated structure and they may (no guarantee, however) make it through the winter.
Soils in Utah are usually alkaline with a pH of 8 or more. The water is also alkaline and may be high in salts. Alkaline soils with a high pH level above 8.0 can impact the health of some landscape plants that are sensitive to high pH soils. The most common problem resulting from high soil alkalinity is chlorotic foliage (foliage that looks dull green or yellowish), a sign of iron deficiency. This deficiency happens because iron becomes immobile (and thus unusable to the plant) in the soil at high pH levels. Iron chelates can be applied as a supplement or, even better, choose plants that are tolerant of high pH soils.
Utah is the second driest state in the nation, normally receiving less than 16 inches of precipitation a year, most of which comes as snow. Very little precipitation falls between June and August, so designing and installing water efficient gardens is extremely important. It is also helpful to water your gardens wisely. For example, water in the early mornings or the evenings after the sun has gone down when it’s a bit cooler. This is when the water is most likely going to soak into the soil and not evaporate before hitting the ground. Keep an eye on how wet your soil is staying. Most plants can tolerate the soil drying out a bit between watering. The best test is to feel the soil- it can be a little dry on the surface, but underneath may still be damp. Also keep in mind the water needs of your plants when following this guideline, some plants like to be dry (cacti, succulents, geraniums, e.g.) while others like to have consistently moist soil (bamboo, impatiens). In addition, we encourage gardeners to plan and design their garden by water zones, situating plants with similar water needs together. For more information, check out the Waterwise Gardening fact sheet on our website.
Gardening in Utah can be rewarding and exciting, particularly with a little preparation and research into your area’s hardiness zone, soil pH, soil alkalinity, and water conditions as well as the needs of the plants you would like to grow.