What Is A Planting Zone?
A growing zone is a classification system used to classify various soil types. Each type of soil has its own unique characteristics. These characteristics are determined by the amount of water available in different areas within the soil profile. Water-holding capacity (HCL) determines how much water can be held in the ground before it becomes too soft or too hard to hold onto. For example, clay soils have high HCL while sandy soils have low HCL. Soil types with low HCL are called loam soils because they do not retain enough water to support plant growth.
Planting zones determine which plants can grow where. Plants that prefer certain growing conditions will flourish there, but others may struggle.
Some crops such as corn and wheat require warm temperatures in order to thrive. Other crops like beans and squash need cool temperatures. Soils with higher levels of organic matter provide better protection from pests than those with lower levels of organic matter.
The USDA’s National Agricultural Statistics Service (NAS) developed a list of the most common growing zones based on data collected between 1935 and 1985. The NCS uses these zones when classifying crop production areas (CPA).
These areas differ slightly from the map above since the NCS uses modern data. The map is a secondary source of information that anyone can use to learn about their area.
Utah Planting Zones – USDA Map Of Utah Growing Zones
You’ve probably seen a map like the one above before. These maps are commonly used by gardeners to choose plants that are well adapted to their specific growing zone.
You may be wondering why our maps look different. That’s because our map displays United States Department of Agriculture (USDA) planting zones. We made this map to help people determine which plants can thrive in specific areas based on the USDA’s hardiness zone system. This system uses data collected by the National Oceanic and Atmospheric Administration (NOAA).
What Is A USDA Hardiness Zone?
Hardiness zones are based on average annual minimum temperatures. The United States National Arboretum created the hardiness zone system to help people find plants that can survive in specific areas. They created the original system in 1961 and have updated it several times since then. The Arboretum recently completed a major overhaul of the hardiness zone system in 2010. This new system is more accurate than the old one and provides a much finer level of control. The new system created a total of 13 map zones. It also assigned hardiness zone numbers from 1 to 13. The map below shows the zones in detail.
These numbers correlate to specific averages for minimum temperatures during a three-year period. These temperatures affect how well plants can adapt to their specific growing conditions.
The Arboretum determines these averages using historical climate data from weather stations within each zone. They divide the United States and southern Canada into zones based on this information. People often use the zones defined by the Arboretum to choose plants. This is why you see them on flower pots at your local garden center.
13 Zones Make Up The USDA Hardiness Zone Map
The map has 13 zones that cover the US, Puerto Rico and Canada. Each zone represents a 10° Fahrenheit range of average minimum temperatures across the zone.
The map only shows the zones in the continental US and southern Canada. Hawaii and territories also have hardiness zones, but they do not use the 10° Fahrenheit system. They use a system that divides the zones into pineapple-shaped areas.
The 13 zones are divided into alphabetical groupings. These groupings create zones with roughly similar average minimum temperatures.
The Arboretum created these groupings based on data from 1981 to 2010.
Sources & references used in this article:
Selection and Culture of Landscape Plants in Utah by LA Rupp, D Libbey – 1996 – digitalcommons.usu.edu
Development of a new USDA plant hardiness zone map for the United States by C Daly, MP Widrlechner, MD Halbleib… – Journal of Applied …, 2012 – journals.ametsoc.org
Gardening Guide for High-Desert Urban Landscapes of Great Basin Regions in Nevada and Utah by R Heflebower – fs.fed.us
Use of individualistic streamflow-vegetation relations along the Fremont River, Utah, USA to assess impacts of flow alteration on wetland and riparian areas by GT Auble, ML Scott, JM Friedman – Wetlands, 2005 – Springer
Random forests applied as a soil spatial predictive model in arid Utah by AK Stum, JL Boettinger, MA White, RD Ramsey – Digital soil mapping, 2010 – Springer
Hydrogeology and spring occurrence of a disturbed juniper woodland in Rush Valley, Utah by FJ McCarthy III, JP Dobrowolski – Proceedings RMRS., 1998 – books.google.com
Habitat relationships of saltcedar (Tamarix ramosissima) in central Utah by JD Brotherson, V Winkel – The Great Basin Naturalist, 1986 – JSTOR
Soil characteristics and plant exotic species invasions in the Grand Staircase—Escalante National Monument, Utah, USA by M Bashkin, TJ Stohlgren, Y Otsuki, M Lee… – Applied Soil …, 2003 – Elsevier