Understanding Gardening Zones: Do They Really Matter?

Whether or not you’re new to gardening, you may be a little confused by some of the terminology.

I started dabbling in growing things when I lived on my own for the first time at age 18. I bought some seed packets to save money on seed starts. But, the U.S. hardiness zones on the backs of the seed packets confused the heck out of me! And back then, the internet was still relatively new. When you wanted to chat online, you still had to wait for the dial up modems and do an ICQ chat. I couldn’t afford a computer either and had to the University’s computer lab for access. So, looking up “U.S. hardiness zone” on the internet wasn’t even on my mind.

I still didn't know what a “gardening zone” or “hardiness zone” meant for a long time thereafter. I learned my basics from my dad, which was to grow what seems logical in your climate, and learn what vegetables and fruits thrive in certain areas. For example, if I know Ong Choy comes from Asia and is grown in warm countries, then I could assume that I could grow it in Texas. Dad taught me via the school of experience.

There is a lot to be said about personal experience, but learning more should be part of it as well. I think I finally understood what a “hardiness zone” or a “gardening zone” was about 10 years ago.

So what is it? The zones are determined by a map that’s created and updated every few years by the U.S. Department of Agriculture. The map divides North America (includes Hawaii and Puerto Rico) into 13 zones by minimum average annual temperatures. The lower number a zone is, the lower the temperatures in that zone. Find your hardiness zone here.

Why It Matters

Knowing your gardening zone can help you determine the right time to plant certain vegetables and flowers and what types of plants will thrive and flourish in your climate. Having a general comprehension and awareness of zones can also help you understand how another gardener’s climate may differ from yours, which is important when you are sharing and exchanging growing information.

You can also make smarter plant purchases. For example, I am in Zone 10b, where the average minimum temperatures are between 35°F to 40°F (1.7°C to 4.4°C). Knowing this, as much as I love lingonberries, I won’t buy them because lingonberries thrive in cooler climates and are hardy in zones 2 to 7. The average minimum temperatures in zones 2 and 7 are between -50°F to -40°F (-45.6°C to -40°C), and 0°F to 10°F (-17.8°C to -12.2°C), respectively. With those vast differences, I don’t think I could even keep a plant alive beyond 3 months!

When the Zones Aren’t As Important

Knowing your zones is important, but they are also just guidelines.

I want to encourage you to push your gardening boundaries a little. Don’t avoid trying something just because it may not be recommended for your zone. The plant may not do super well, but it can still do okay in many cases.

In zone 10, I know I can push the boundaries of some plants that are typically hardy only to zone 8 or 9. I just have to be smart about the cultivars I choose, and may need to take extra steps to protect the plants. You can do the same, as long as you’re willing to try, including failing. Either way, you would have learned something from trying.

I have a peppercorn vine. Yep, the same kind that produces black peppers, Piper nigrum. Peppercorn is a perennial vine that is indigenous to Southern India, and is hardy in zones 12 and 13. Some gardening sites say that the vine is hardy in zones 10 and 11 as well, but I would say that they are more of a tender perennial in zones 10 and 11, meaning that to grow it well in zones 10 and 11, the plant requires a bit more TLC. The plant loves a warm tropical climate and stop growing when the temperatures dip below 65°F (18°C). The peppercorn vine won’t tolerate frost.

In zone 10b, the average minimum temperature is a bit too chilly for the optimal growing conditions preferred by the plant. Furthermore, my zone does get the occasional frost and near-freezing winds, which are all conditions the plant cannot tolerate. So, in order to grow it successfully in my zone, I have to protect it and bring it indoors in the winter and provide it with a source of heat, like a heating mat. Otherwise, it will likely succumb to the cold and die. In fact, it almost died because I’m too cheap to turn on the heater in the house in the winter and it was in a chillier part of the house. I saved it by putting it on a heating mat.

Be Bold, Be Smart

In summary, use the plant hardiness zones as a guideline for your planting decisions. However, don’t let those zones be rigid guidelines, because within each growing zone, there are variations in microclimates too. With a little care, you can push the boundaries a bit.

[Link: article on microclimates]

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