Plant the hardy unusual roots in early spring, around the April 3 to April 16 frost window, and hold the tender ones until after it. The dates below come from NOAA climate normals for the Baltimore reference station, and they are odds, not promises. Western Maryland and the Eastern Shore both sit outside those numbers. Here is how to read them, and where to confirm them for your own county.
The short answer for Maryland
The last spring frost in Maryland falls between April 3 and April 16, and the first fall frost between October 26 and November 5. Both ranges come from the NOAA NCEI 1991-2020 Climate Normals, and both measure the same thing: the 30 to 70 percent probability band for a 32°F freeze. April 3 is roughly where the odds of another freeze are still near 70 percent. April 16 is where they have fallen to about 30. In the fall the band runs the other way. The NOAA station data is for Baltimore, so treat the dates as a reference point, not a rule for every yard in the state.
A frost date is not a deadline. A “last frost of April 16” means that in roughly three springs out of ten, a 32°F night still shows up after that date. If you plant by the calendar and ignore the forecast, you are placing a bet, and a 30 percent chance of losing seedlings is a bad bet for anything tender.
Turning the window into planting dates
Most sowing decisions follow from where a root crop sits relative to that spring band. The frost-tolerant roots, the kind that shrug off a freeze as seedlings, can go in as soon as the soil is workable, which in Maryland means inside or even ahead of the April 3 to April 16 span. Salsify, scorzonera, parsnips and burdock fit that description, and the ground does not need to be warm for them, only thawed and not waterlogged. For more on which ones earn space in a Maryland bed, see The Best Unusual Roots to Grow in Maryland.
Tender roots work the other way. Anything that blackens at 32°F belongs after April 16, and a sensible gardener adds a cushion of a week or two beyond the end of the band. Warm-season roots also want warm soil, and soil lags behind air temperature by weeks. A mild afternoon in mid-April tells you very little about what is happening six inches down.
The fall end of the calendar does two jobs. For long-season roots, the October 26 to November 5 band is the date to count backward from: the crop has to be mostly finished, or properly mulched, by then. For hardy roots left in the ground, the same dates mark when the sweetening begins, since cold nights push starch toward sugar in parsnips and similar crops. This page has no verified root-by-root sowing table for Maryland, so it sticks to the frost evidence and the logic that follows from it.
What will not work here
Maryland’s problem is rarely a short season. The trouble is what happens in the middle of it, and what the winter does at either end.
Start with the heat. Maryland summers are hot and humid, and cool-season roots sown late in spring tend to meet July as half-grown plants. Heat-stressed roots turn woody, bolt, or stall. The better approach is to sow the cool-loving types early enough to size up before summer, or to wait for late summer and let them mature in the cooling weather before the October 26 to November 5 frost band arrives.
Humidity punishes close spacing. Crowded foliage stays wet after rain and dew, and in a humid state that invites leaf spot and rot. Thin earlier and harder than the seed packet’s minimum suggests, and give the rows room to dry out.
Watering weekly and hoping for the best does not travel well either. Maryland’s summer rain tends to arrive in bursts, so a root bed can swing from soaked to parched in days. Those swings cause splitting and forking, and can leave a crop tough and bitter. Mulch and steady moisture beat a fixed weekly schedule.
Winter sets the other limit. The mean daily minimum of the coldest month at the Baltimore reference station is 25.4°F (NOAA NCEI Climate Normals 1991-2020). That is an average of the lows, not the record, and plenty of nights fall below it. Hardy roots handle that fine, and many will overwinter in the ground under mulch. Tender, tropical-origin roots will not survive a winter in an unprotected bed. They have to be lifted and stored, or grown as annuals and replanted each year, and no amount of optimism about “mild Maryland winters” changes that.
The last failure is timing by enthusiasm. A warm week in late March convinces plenty of people to plant everything at once, and a freeze afterward can wipe out a tender planting entirely. Hardy roots forgive an early start, and tender ones do not. Planning around that difference is most of the work, and the wider context is in Growing Unusual Root Crops in Maryland.
What changes across Maryland
There is no single Maryland answer, and the hardiness numbers say so directly. The USDA Plant Hardiness Zone Map 2023, built from 1991-2020 normals, places the state in zones 5b to 8a. That is nearly three full zones, each representing about a 10°F step in average annual extreme minimum temperature. The system rests on one variable only, the coldest night of the year, so it says nothing about summer heat, humidity or rainfall.
The dates in this article are anchored to Baltimore, and the other parts of the state differ from it in predictable directions:
| Area | How it compares with the Baltimore reference |
|---|---|
| Western Maryland (Garrett, Allegany) | Mountainous, and runs weeks later in spring; frost can come earlier in fall |
| Baltimore reference station | Last spring frost April 3 to April 16; first fall frost October 26 to November 5 |
| Eastern Shore | Runs milder, so spring planting can start somewhat sooner |
For a reader in the western mountains, the practical shift is to move every spring date later by weeks and to treat the fall deadline with more suspicion. Cold air pools in valleys and hollows, and even a few hundred feet can change when the ground thaws. Long-season roots are the first thing to cut from the list up there.
On the Eastern Shore, milder conditions give an earlier start and a slightly later finish. That buys room for the slower roots, though summer heat still arrives with the same force, so the heat warnings above apply.
Do not guess your own zone from this page. The USDA map lets you search by ZIP code. Use it alongside the frost dates, not in place of them, since one describes winter survival and the other describes planting risk.
Where to check this for your own county
The best next stop is University of Maryland Extension, the state’s land-grant extension service. This page is a state-level view built on one reference station, and a county recommendation beats it every time. Extension staff work with local soil, local frost pockets and local pest pressure.
Look for two things. The first is a local planting calendar: a vegetable planting guide that lists spring and fall dates by region or county, which you can compare with the April 3 to April 16 and October 26 to November 5 bands here. If your county’s dates differ from Baltimore’s, trust the county’s. The second is any record of varieties trialled near you. Unusual roots are a thin area for formal trials, so a lack of results for something like scorzonera does not mean it fails. Ask the local Master Gardener program or the county office whether anyone in the area has grown it, and what they saw.
One caution on the source material for this page: the extension calendars on file are lawn-care schedules from another state, which do not apply to root crops or to Maryland, so none of their dates appear here.
Checking this against your own garden
Every date above is an average over thirty years of records at one weather station. Your garden’s own signals will beat it, and two of them need no equipment.
- Soil warmth by feel. Push your bare hand into the bed to about the depth of your knuckles. If the cold makes your hand ache within a minute, tender roots should wait. A bed that feels cool but not painful suits the hardy types. A south-facing slope or a raised bed will pass this test days before a low, shaded corner does, and that gap is your microclimate.
- The first true leaves. Sow a short row of radishes at the start of spring. When the first true leaves show, after the rounded seed leaves, note the date. A fast, sturdy start says the ground is ready for the next crop, and a slow start says it is not.
Common questions
When is the last frost in Maryland?
For the Baltimore reference station, the last spring 32°F freeze falls between April 3 and April 16. That is the 30 to 70 percent probability band from NOAA’s 1991-2020 normals, so a later freeze is still possible. Western Maryland runs weeks later, and the Eastern Shore is milder.
Can I plant unusual roots before the last frost date?
Frost-tolerant roots, yes, once the soil can be worked. Tender ones should wait until after April 16, with a margin added, because a freeze after that date is still possible in roughly three springs out of ten.
What USDA zone is Maryland?
Maryland spans zones 5b to 8a on the USDA Plant Hardiness Zone Map 2023, so there is no single answer. Check the USDA map by ZIP code to find where you fall, because the zone reflects only the coldest night of the year.
Do I need to dig tender roots before winter?
Yes. The mean daily minimum of the coldest month at Baltimore is 25.4°F, and tropical-origin roots will not survive in an unprotected bed. Lift and store them, or replant each spring. Hardy roots can stay in the ground under mulch.