Hardiness Zone Change

By Debbie Roland and Emmy Ulmschneider, Master Gardeners

Gardeners here and on social media have been all in a “tizzy” about the USDA assigning new gardening zones. So what is a gardening zone? The USDA divides North America into 11 hardiness zones. Zone 1 is the coldest; zone 11 is the warmest.

The United States is primarily the country that uses the hardiness zone map, although England sometimes uses this reference as well.

The plant hardiness zone is an assessment of the last thirty years of weather that shows the average low temperature in your region. The map just shows what zones are where. They have nothing to do with your growing season or with your first and last frost date. Those can be very different in places that may be in the same zone.

If you pull the USDA hardiness zone map I (Debbie) show to be in Zone 8a (northeast Ector County) and Emmy is in Zone 8b (Midland County). My average low temperature is 10 to 15 degrees and Emmy’s is 15 to 20 degrees even though we only live about 10 miles apart.

In vegetable gardening it doesn’t matter what zone you are in since you are starting new seeds at the beginning of each season and you pull those at the end of that growing season. The first and last frost dates are important to know when growing your own food so you know when to plant.

And bear in mind that even within your yard microclimates can affect how plants grow. Planting tender plants like citrus against a wall that absorbs daytime heat places it in a micro-climate that is warmer than a more exposed area. The zones are a guide but you still need to determine for yourself what will and won't work in your garden.

If you are an ornamental gardener (such as roses or any plant that is left out over the winter season) you need to know if these plants will survive the low temperatures in your area. Researching the plant and reading the plant label will help you know if you can successfully grow a plant, shrub or tree.

Perennial actually means “through the years”. These plants will die back to the ground and come back next season. The low temperatures will not apply to them unless there is an extreme Snowmageddon type weather event.

So what does this mean for you? Probably not much. You need to look at your yard, whether or not you have microclimates within your yard and what your growing experience with each plant has been. If you are just planting that plant for the first time log on to our website (westtexasgardening.org) and look at our recommended plant lists. The lists were created from recommended lists for Texas and local Master Gardeners have eliminated plants that, in their experience, will not grow well in the West Texas climate extremes.

If you have questions, call the AgriLife office in Odessa at 498-4071 or in Midland at 686-4700. Additional information, and our blog for access to past articles, is available at westtexasgardening.org. Click on “Resources”.