What is your “zone” – and does it really matter? – Picayune item

What is your “zone” – and does it really matter?

Published 9:43 am Wednesday 23 November 2022

Every day I get emails from gardeners and field questions on the Mississippi Gardening Facebook page about growing various plants where the authors mention their USDA plant hardiness zone. Which to me has little to do with the reality of gardening in Magnolia State.

Here I go again, seemingly contesting the production efficiency dogma preached by my fellow gardeners. But as you and I know, and Aunt Mamie, who is a damn good gardener even though she’s never taken gardening master classes, there are some things we gardeners say that are technically correct but not strict requirements for the average home gardener are success.

It’s like adding at the bottom of all my emails that I’m a twin; My birthday month doesn’t take into account my upbringing, my attitude, where I live, what style I choose, or whether I prefer wine or a strong beer. These are conversation starters, not insights into my overall character.

Basically, what these serious gardeners are telling me is simply whether it will freeze in the winter. Aside from summer annuals and tropical plants that don’t tolerate cold weather for long, the actual low doesn’t matter that much — a freeze is a freeze, whether it’s in the single digits, hovering in the tens for a few days, or just temporarily dipping into the uppers 20s along the coast.

I mean, England, which is on the same latitude as Nova Scotia, should be super cold for most of the winter, but because it’s surrounded by warm Gulf Stream waters, it’s in the same USDA Zone 8 as most of Mississippi. To reiterate, Mississippi and England are in the same zone. The same with Seattle. All three places rarely get into the teens, rarely have ice.

In fact, coastal England, Ireland and even Scotland are the same Zone 9 as our coastal counties, but they grow things we can’t.

Regardless of how the zone charts tell us that David Austin roses should grow in Mississippi, it doesn’t make them that way. They have a hard time coping with our heavy rains and hot humid summer nights.

That’s my point here. No matter what the charts say, seasoned gardeners know that cold weather isn’t the only thing that limits plants. Some, like bananas, amaryllis, and citrus can take a little frost but not a prolonged or really deep frost, but for the vast majority of good Mississippi garden plants it’s about the same.

This is because there are other important factors that affect plant growth, including summer heat (especially at night), heavy rainfall, long sunny but also dry periods in winter, sun or shade, soil type, nearby tree roots, and how everything is changed , how we plant, water and fertilize, as well as insects and diseases. Add a microclimate that transforms the environment in the same way a normally hardy garden plant cannot survive in a mall parking lot.

What I think we need is a Mid/Lower/Coastal South map that overlays average frigid winter temperatures with dramatic midweek highs and lows, plus our average first and frost dates, plus hot, muggy summer nights, which actually suffices for many Plants, our too-wet winters and too-dry summers, pathetic dirt, incredible pest pressure and busy gardeners’ schedules.

Whether your zone is 7, 8, or 9 (forget that worthless “a” and “b”), it only matters to a few plants along the coast. And wherever gardeners protect border plants, everything becomes moot.

Where it’s freezing, zones like zodiac signs aren’t good indicators of success.


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