Hardiness Zones vs. Heat Zones: What Georgia Gardeners Need to Know This Spring
If you’ve been watching the forecast lately, you’re not alone. Every spring in Georgia, gardeners start nervously refreshing their weather apps when a late-season cold front rolls in. Suddenly we’re all asking the same question:
“Are my plants going to survive the cold tonight?”
That’s where hardiness zones come in. But while we’re busy protecting plants from spring chills, there’s another important factor many gardeners overlook — heat zones.
And if you’ve ever watched your thriving garden slowly struggle by late summer, heat zones might explain why.
What Are Hardiness Zones?
The USDA Hardiness Zone system tells us how cold our winters can get. It’s based on the average minimum winter temperature, which helps gardeners determine whether a plant can survive the cold in their region.
Here in North Georgia, most of us fall into Zone 7b–8a, meaning winter temperatures can drop as low as 5–15°F. This is why every spring we keep a close eye on late frosts. Even though warmer weather is arriving, tender plants can still be damaged by sudden cold snaps.
Hardiness zones help answer an important question:
Will this plant survive our winters?
But that’s only half the story for Southern gardeners.
The Other Side of Gardening in the South: Heat Zones
Once spring settles in and the risk of frost passes, our focus shifts from cold… to heat. Heat zones measure the number of days a region experiences temperatures above 86°F (30°C).
Why that number? Because for many plants, photosynthesis slows dramatically once temperatures climb above about 86–87°F.
When that happens:
Growth slows or stops
Plants become stressed
Leaves wilt or turn bitter
Many herbs and greens bolt early
If temperatures cool overnight, plants may recover. But during long stretches of heat and warm nights — which Georgia summers are famous for — plants can remain stressed for weeks.
Why Georgia Gardens Often Struggle in Late Summer
Many gardeners assume summer is when plants should thrive. But in reality, many herbs and leafy plants prefer cooler temperatures and actually grow best in spring and fall.
For example, herbs like cilantro are cool-season growers that tend to bolt when exposed to too much heat and direct sunshine.
That’s why you may notice a pattern:
Gardens thrive in April and May
Plants begin slowing down in July
By August, everything looks a little tired
It’s not bad gardening, it’s simply heat stress.
The Secret to Gardening in Georgia: Seasonal Windows
Instead of thinking of gardening as one long growing season, Southern gardeners often work with multiple planting windows.
Spring Garden
March – May
Perfect for leafy greens, herbs, and cool-season crops.
Summer Garden
June – August
Best for heat-loving plants like basil, peppers, okra, and roselle hibiscus.
Fall Garden
September – November
Another opportunity for cool-season herbs and greens.
Understanding when plants thrive, and when they struggle, can make a huge difference in garden success.
A Helpful Way to Think About It
Hardiness zones answer one question: “Will this plant survive our winter?”
Heat zones answer another: “Will this plant survive our summer?”
And here in Georgia, both matter.
As We Head Into Growing Season…
Right now, many of us are watching the forecast for late frosts and protecting tender plants. But as you plan the rest of your garden this season, it’s just as important to think about how plants will handle our summer heat. Understanding both hardiness zones and heat zones helps you choose the right plants, and the right planting time, for a thriving garden all year long.
At Planted Wellness Co., this idea of “right plant, right time” is exactly why we grow and sell our plants in seasonal small batches.
You might notice that some herbs only appear at certain times of the year. For example, we’re often asked in the middle of summer if we carry cilantro — but here in Georgia, cilantro is a cool-season herb that thrives in spring and fall, not in the peak of summer heat. So that’s when we offer it.
Our goal isn’t just to sell plants, it’s to help you succeed with them. By offering plants at the times they’re most likely to thrive, we can help you build a garden that works with Georgia’s climate instead of fighting against it.
Because at the end of the day, our mission is simple: to cultivate the wellness of gardens and lives.
