Most gardeners in Georgia can sow or plant unusual root crops twice a year: once after the soil warms in spring, and again in late summer for fall and winter harvests. The Atlanta station puts the last spring freeze between March 11 and March 29, but that date is only a signpost. What decides success is soil warmth, summer heat and choosing root types that suit both. The same questions come up for Celeriac, Kohlrabi, Horseradish and Jerusalem Artichokes, and Georgia answers them differently from most states.
When the soil is warm enough in Georgia
NOAA’s 1991-2020 Climate Normals for the Atlanta station (USW00013874) put the last spring 32°F freeze between March 11 and March 29. That range is the 30-70% probability band, so it describes odds, not a promise. Some years a freeze will slip past the late end. Say it once and move on: plan around the range, keep row cover handy.
The frost date also answers a slightly different question than the one root crops ask. Frost tells you when air temperatures stop dropping below freezing. These crops care about the soil, and soil lags the air. It warms after the frost risk ends, not with it, which is why a bed can be frost-free in late March and still be too cold and wet for seed to do much. A cheap soil thermometer pushed a few inches down tells you more than a calendar. Your state extension service publishes the soil temperatures each crop wants, and the University of Georgia Extension is the place to find them for Georgia conditions.
One caution on the dates themselves. Atlanta is an urban airport heat island. North Georgia and the mountains freeze several weeks earlier in fall, and the coastal plain runs milder. Treat the Atlanta numbers as a reference point, then shift them for your own ground.
Planting order by type
Cool-season roots such as turnip, rutabaga and kohlrabi are the first to go in once the soil can be worked. Celeriac is set out as transplants and wants a long, steady stretch of growth. Horseradish goes in as root pieces in spring and then sits there for years.
Jerusalem artichoke needs its own warning, and the warning comes before the planting advice. Once planted, it is effectively permanent. Every fragment of tuber left in the soil regrows, so digging it out never quite works. Site it where a spreading stand is welcome: a fenced corner, a bed with a hard edge, a spot far from the vegetable rows. Some gardeners confine it to a large sunken container or a bordered strip, though even then small tubers escape. Plant the tubers after the last freeze risk has passed, and expect to harvest and replant the same patch indefinitely.
The tubers store inulin rather than starch, and in many people that causes digestive discomfort. It is a plain fact of the vegetable. A small first portion is the sensible way to find out how you react.
This page names no varieties. The ones trialled in Georgia soil are the only recommendation that means anything, and extension trial data is where they live.
How long the season lasts here
Take the same Atlanta station and count. The first fall freeze falls between November 13 and December 1. From the earliest spring date (March 11) to the earliest fall date (November 13) is 247 days. From the latest spring date (March 29) to the latest fall date (December 1) is also 247 days. Mix the extremes and the window runs from 229 days (March 29 to November 13) to 265 days (March 11 to December 1). Call it roughly seven and a half to eight and a half months between freezes.
That length matters because of what it allows. A window this long gives room for a second sowing. A short-season gardener gets one go at turnips or kohlrabi, and that first sowing is the whole crop. In Georgia, a spring planting can be harvested and a second sowing started in late summer, timed so the roots mature in the cooler weeks of fall. The succession sowing guide on this site walks through spacing those sowings so the harvest comes in waves instead of one glut.
The window also changes the transplant math. Where the season is short, every transplant needs a clean root system, because a check at planting costs weeks you do not have. Georgia’s longer frost-free stretch gives a transplant more room to recover. Even so, celeriac seedlings that sulk after a rough move can lose ground they struggle to regain, so handle them gently and keep the roots intact.
Be careful with these numbers in one direction. A long frost-free window is a calendar fact, not a guarantee that every crop thrives across all of it. Summer sits in the middle of that window, and the middle is the hard part. That is where the next section picks up. Gardeners in colder states face the opposite problem, as the pages on Growing Unusual Root Crops in Ohio make clear.
Heat and water in Georgia
This page does not carry a verified count of days above 90°F or a summer rainfall total for Georgia, so it will not guess at either. What can be said safely is qualitative: Georgia summers are hot and humid, and that combination, more than any single temperature, shapes what happens to root crops between June and September. Heat slows or stalls cool-season roots. Humidity favors fungal disease and rot, especially where the soil stays wet around the crown.
Two facts govern this group of crops. The first is season length. Celeriac is the long one, and a window of 229 to 265 days between freezes means it can finish on the calendar here. Whether it finishes well depends on how it handles summer, so the sensible approach is to time celeriac so most of its growth lands in the cooler shoulders of the year, with mulch to keep the roots cooler through the heat.
The second fact is the winter low. The coldest month at the Atlanta reference station has a mean daily minimum of 35.6°F. That is an average night, not a record low, and it sits above freezing. In Atlanta terms, that makes it reasonable to leave hardy roots and the perennials (horseradish and Jerusalem artichoke) in the ground under a layer of mulch. Cold snaps still happen, and the USDA Plant Hardiness Zone Map (2023) runs from 6a to 9b across Georgia. That is a territory-wide range, and the mountain counties sit at the cold end of it. If the soil is going to freeze where you garden, lift what you want to keep and store it before it does.
Storage touches food safety, so inspect before you trust. Look over every root for soft patches, weeping spots or a moldy crown. Any of those ends the question for that root; do not cut the bad part away and keep the rest. A root that looks sound on the outside is not proof that it is safe, and no keeping time can be promised from a page like this one.
Horseradish deserves a plain note at the preparation stage. Grating a fresh root releases compounds that burn the eyes and airways. Work with ventilation, keep your face away from the bowl and step back after grating. It is not a joke, and it catches people who have never handled the fresh root.
Gardeners at the other extreme will find a different pattern in Growing Unusual Root Crops in Arizona, where dry heat is the main constraint instead of humidity.
Which these root crops suit Georgia
Reason from Georgia’s own facts. A long season with hot summers favors types that mature before or after peak heat and can be given airflow and shade at the root. A humid climate makes disease resistance the first criterion, ahead of flavor or size. That is the logic, and it works by type.
| Root crop | What Georgia conditions favor |
|---|---|
| Turnip and rutabaga | Sowings timed for cool weather, spring and fall, with a second sowing in late summer |
| Kohlrabi | Early spring and fall sowings; heat is the enemy |
| Celeriac | Growth timed for the cooler shoulders, mulched roots, steady moisture |
| Horseradish | A permanent bed with good drainage; hardy enough to overwinter under mulch in Atlanta terms |
| Jerusalem artichoke | A contained, deliberate site, since it never leaves |
Turnip, rutabaga and kohlrabi are all brassicas. They share their pests and diseases with cabbage, kale and mustard, so a gardener who moves them into a bed where cabbage grew has rotated nothing. Rotate by plant family, and give brassicas a different family to follow.
No variety is named on this page, and that is deliberate. Cultivar names that work in one county can fail in the next, and the only recommendation worth following is one that was trialled in Georgia ground. The state’s land-grant extension service holds that information. Contact University of Georgia Extension or your county office for the varieties tested near you, and ask specifically about disease resistance, since humidity makes that the deciding trait.
Common questions
Can celeriac really finish in Georgia?
On the calendar, yes. The window between freezes at the Atlanta station runs 229 to 265 days. Heat is the harder test, so time its growth for the cooler stretches and mulch the roots.
When should Jerusalem artichokes go in?
After the last freeze risk has passed, in a site you are happy to give up permanently. Any tuber left behind regrows.
Can I plant turnips where cabbage grew?
Avoid it. Turnips, rutabagas and kohlrabi are brassicas and share troubles with cabbage, kale and mustard. Rotate to a bed that has held a different plant family.
Do the Atlanta dates apply where I live?
Only roughly. They come from one airport station in an urban heat island. North Georgia and the mountains freeze several weeks earlier in fall, while the coastal plain runs milder, so adjust both ends of the window for your own ground.