January 21, 2021

What gardening zones can't tell you

While you probably already know your growing zone, there are a number of important factors for successfully growing your own food that gardening zones can’t tell you…

“What gardening zone am I in?” is one of the more common questions on gardening forums. But there is a lot more to gardening zones than just the area of the country where you are located. In fact, growing conditions and temperatures can vary widely within states, local regions, and even your own garden plot! As the video below explains, knowing your overall growing zone is just the beginning.

A growing zone map can tell you average low temperatures and average first and last frost dates for a given season in your general region, but there are so many other factors that can impact your local temperatures and therefore your success with growing certain crops. What other information do you need to know to help your garden grow and thrive?

Here are 5 additional considerations to keep in mind that your gardening zone can’t predict:

1.) Growing zone maps show only average minimum temperatures – not extremes.

This means you can have unseasonably cold winters where temperatures may fall well below what is shown on the map. This can impact what crops you can successfully grow in the fall and winter months. If you choose veggies based on their hardiness to a certain temperature, you could end up losing much or all of your harvest if your winter temperatures fall below normal. It would be more helpful to know what the extreme low temperatures for your area may be, in order to choose crops that will survive in that temperature range just in case you have an extra cold winter.

2.) It doesn’t tell you how hot the summers may be.

Especially as our climate continues to warm, it is just as important to know what average summer temperatures may be in your area. A climate data map or chart can be very helpful here, as your gardening zone may not be a good predictor of how many days of extreme heat are average for your area.  You will especially want to look at how many days in a given time frame average above 86 degrees Fahrenheit. Many vegetables either can’t survive in sustained temperatures above 86 degrees, or will slow or stop production. This doesn’t mean that you can’t grow in those areas, but if your area sees average temperatures above this point for certain months of the year, you may want to choose more heat-resistant varieties, grow in partially shaded areas, or skip those months altogether and focus your gardening efforts on the cooler months. This plant heat zone map will be very helpful in your garden planning process.

3.) It can’t tell you how much sun or daylight you get.

One of the most important factors for growing most types of vegetables is how much sun (or daylight) your garden area receives. While there are some crops that will grow well in shady areas, most crops (especially fruiting crops such as peppers, tomatoes, melons, or squash) need quite a bit of sunlight to grow and produce well. Day length will also influence the size and productivity of your plants – and gardening zones don’t show day length – although that would certainly be a useful addition.

4.) Gardening zones have nothing to do with your soil.

If I had to pick just one factor that can make or break your garden’s success, it is the health and makeup of your soil. Rich, healthy soils with lots of organic matter are essential for growing a healthy and productive garden. Obviously, your growing zone has nothing to do with this essential factor. Fortunately, this is one aspect that you have much more control over than you do your gardening zone. There are numerous ways to build and improve your soil over time, even if you’re starting out in an area with poor soil to begin with. Compost, mulch, and soil testing combined with any appropriate soil amendments are key.

5.) Your gardening zone doesn’t account for microclimates.

Even if you live in a certain growing zone, your garden can experience several different microclimates all within the same garden space. Microclimates are areas where the temperature may vary (sometimes widely) from the surrounding area. This may be influenced by a number of factors, from the presence of water bodies or light-reflecting surfaces (like bare ground or a nearby brick or stone wall, for example), to your local topography, the amount of snow cover during the winter, or sun and wind exposure. Each of these factors may significantly impact the temperature in different areas of your garden.

As you can see, there are many factors that will influence the success and productivity of your vegetable garden besides just what gardening zone you are in. In order to truly garden well, you will want to do a bit of research and find out the number of days your area averages above 86-degrees, the number of days below freezing, and your first and last average frost dates. These three pieces of data will tell you the average length of your main growing season. It will also be helpful to know the average day length during your growing season, and the number of hours of sun your garden space receives each day. Once you have determined these numbers, you can properly plan for which crops to grow and when, and whether you need to take steps to improve your growing area by implementing strategies to change or improve your microclimate(s).

 

(Image Source: USDA-ARS and Oregon State University (OSU), Public domain, via Wikimedia Commons.)

 

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About the author 

Rose S.

An avid gardener since childhood, I love sharing my passion for gardening with others! I have gardened in a number of different climates and settings, from large fenced garden plots, to tiny patio and container gardens, and I firmly believe that everyone can learn to grow at least some of their own food - no matter where you live. Growing your own food can help you take control of your own health and food supply, and there has never been a better time to get started!

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