Celeriac, kohlrabi, horseradish and Jerusalem artichokes can all be grown in Missouri, and the soil matters more than the calendar. At Kansas City International Airport (MCI), the last 32°F freeze falls between April 6 and April 20. These roots wait for warm ground, though, and that comes after the frost risk ends. For the crops themselves, start with Celeriac, Kohlrabi, Horseradish and Jerusalem Artichokes.
When the soil is warm enough in Missouri
The date most gardeners want is the one in NOAA’s 1991-2020 Climate Normals: April 6 to April 20 for the last spring freeze at the MCI station, the 30 to 70 percent probability band for a 32°F reading. Treat it as an anchor, and adjust for where you live. MCI sits well north of the city, so downtown Kansas City runs about five days earlier in spring, and southern Missouri is milder still.
A frost date is a probability, not a promise. Some years the last freeze comes earlier than that band, and some years it comes later.
The frost date is also a proxy. Celeriac and kohlrabi seedlings, and horseradish and Jerusalem artichoke pieces, respond to soil temperature, not to the last freeze. Air warms in a day, but a bed holding cold water from March rain takes weeks. Soil warms after the frost risk ends, not along with it. A cheap soil thermometer pushed a few inches into the bed tells you more than any date. Your state extension service publishes the soil temperature thresholds for each crop (more on that below).
In practice, kohlrabi is the forgiving one, a cool-season brassica that can go out around the end of the frost band. Celeriac is the opposite. It is started indoors well ahead and set out only once the ground has lost its chill, because a cold snap can push young plants toward bolting instead of building a root. Horseradish roots and Jerusalem artichoke tubers can go into the ground as soon as it is workable and no longer waterlogged.
Site Jerusalem artichokes before you plant them
This is the planting gardeners most often regret. Jerusalem artichoke is effectively permanent once planted. Every fragment of tuber left in the soil regrows, and digging the bed over only scatters more pieces. Give it a corner you will never want for anything else: a bed edged by lawn or pavement, or a deep container with a solid bottom. Never put it in the middle of a vegetable plot you rotate. Harvest thoroughly, and expect shoots to come back anyway.
The tubers store inulin instead of starch, and many people find that they cause digestive discomfort. Start with a small first portion and see how you react.
Horseradish needs a plan too
It spreads from root pieces, so it also belongs in a spot you can leave alone. Preparation is a separate hazard. Grating a fresh root releases compounds that burn the eyes and airways. Open a window, run a fan, and keep your face well back from the bowl.
How long the season lasts here
Take the late edge of the spring band and the early edge of the fall one. The last freeze falls between April 6 and April 20, and the first fall freeze between October 18 and October 29 (same NOAA station and normals). April 20 to October 18 is about 181 days, and April 6 to October 29 is about 206. Your window sits somewhere between those two numbers, shifted a few days either way depending on your location in the state.
What does that length allow? Mostly, it allows a second chance. A window of roughly six to nearly seven months leaves room for a spring kohlrabi sowing to come out of the ground in time for a second sowing for fall, started in the heat of summer so it matures in cooling weather before the October freeze band opens. A northern territory with a shorter window rarely has that option, and the first sowing is the only one. Here, a failed or bolted first sowing is not the end of the year. The succession sowing guide on this site covers spacing the second round.
The window also changes whether transplanting is worth the risk to the roots. Celeriac and kohlrabi both resent root disturbance, and a check at transplanting, with roots left intact and the seedling set at the same depth it grew, costs a few days of growth. Where the season is short, that loss can decide the crop. In Missouri, with a window this long, indoor starts and careful transplanting are affordable, and celeriac in particular benefits from them. Horseradish and Jerusalem artichokes are not affected, since they go in as root pieces and make use of whatever season is left.
For comparison with states that have different seasons, see Growing Unusual Root Crops in Maryland and Growing Unusual Root Crops in Washington.
Heat and water in Missouri
This page does not carry a verified count of days above 90°F or a figure for summer rainfall, so it will not quote one. Counts like that come from a reference station and describe that station, not the whole state, and Missouri runs from the Kansas City area to the milder south. What can be said is how the crops behave. Kohlrabi and celeriac are cool-season plants, and summer heat stresses them, tending toward woody kohlrabi and a stalled celeriac root. Irregular watering splits and toughens both. Mulch, steady moisture, and some afternoon shade at the root help more than anything else you can do in July.
Where summers are humid, expect foliar disease on celeriac and fungal rot in wet soil, so airflow between plants and drainage matter. The University of Missouri Extension publishes local weather and disease information through its county offices.
Two facts govern the group. The first is season length. At about 181 to 206 days between the freeze bands, celeriac, the long one, has a real chance of finishing here, provided you compare the days to maturity on the seed packet with your own window. It is not a certainty, and a late start eats the margin.
The second is the winter low. At the Kansas City reference station, the mean daily minimum of the coldest month is 19.5°F. This is not the record low. The USDA Plant Hardiness Zone Map (2023, built on 1991-2020 normals) places Missouri in zones 5b to 7b, so the cold varies across the state. At that figure, ground freezes in the north and winter can bring colder spells than the average suggests. It decides what stays in the ground under mulch and what comes out before the soil freezes.
| Crop | Winter plan |
|---|---|
| Horseradish | Hardy perennial, can stay in the ground under mulch |
| Jerusalem artichoke | Hardy perennial, can stay in the ground under mulch |
| Celeriac | Lift before the soil freezes and store |
| Kohlrabi | Harvest before hard freezes and store, or eat fresh |
Stored roots call for inspection, not trust. Check them often. A soft patch, a weeping spot or a moldy crown ends the question for that root, and a firm appearance never proves a root is safe to eat. No storage duration is promised here, since it depends on conditions you cannot control from a page.
Which these root crops suit Missouri
The choice here comes down to type, and not to cultivar name. This page cannot source varieties trialled in Missouri, and naming one from memory would be guessing. A gardener who plants a variety that failed locally has lost a season. So the right answer is the University of Missouri Extension, whose trials and county offices are the only recommendation that means anything for your soil. Ask for the varieties trialled near you.
What this territory’s facts do tell you is how to choose among types. A window of about 181 to 206 days is generous enough that you need not hunt for the fastest types of everything. But for celeriac, favor an earlier-maturing type, because the margin is thinnest there. Heat favors plants given airflow and shade at the root, so space them generously and mulch. Humidity makes disease resistance the first criterion, and seed descriptions state it.
One caution on rotation. Kohlrabi, like turnip and rutabaga, is a brassica. It shares its pests and diseases with cabbage, kale and mustard, so a gardener who rotates it into a cabbage bed has rotated nothing. Check the rotation page on this site before you plan the beds.
For the perennials, there is less to choose. Horseradish and Jerusalem artichoke are tough and cold-hardy through the Kansas City minimum. Site them for permanence, as above, and treat the winter low as settled.
Common questions
Is April 6 to April 20 safe for planting everything?
No. That band is a 30 to 70 percent probability of a 32°F freeze at MCI, and the soil may still be cold after it. Check the soil temperature before you plant.
Can I leave celeriac in the ground over winter in Missouri?
Not safely. With a coldest-month mean minimum of 19.5°F at the Kansas City reference station, plan to lift it before the soil freezes. Horseradish and Jerusalem artichokes are the ones that can stay under mulch.
Where should I put Jerusalem artichokes?
In a place you will never want for anything else. Any tuber fragment left behind regrows, so avoid rotated vegetable beds. Many people find the tubers cause digestive discomfort, so begin with a small portion.
Which varieties should I buy?
Ask University of Missouri Extension for the varieties trialled in your part of the state. This page names none, because it has no local trial results to base them on.