Harrison County, in Mississippi, sits in USDA hardiness zone 9a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
A short list that earns its place here — artichoke, fig, california poppy, and cabbage — with any one site's soil, sun, and drainage making the final cut.
Harrison County lies within the Gulf Coast — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Harrison County holds more than one microclimate.
Soils and elevations shift across Harrison County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Harrison County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Harrison County — the short answer
Harrison County, Mississippi: USDA zone 9a, about 309 days between hard freezes, across 367K acres.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 4
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 10
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~309
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 367K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 9a is Harrison County's average, not your lot's — a low corner or a tree line moves it. Against Harrison County's 309-day season, see what your own ground reads.
Heat and winter chill in Harrison County
Across a year, Harrison County accumulates about 6,509 growing degree days above 50°F, about 1,111 more than the middle Mississippi county — ahead of every other Mississippi county. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Winter banks about 299 hours below 45°F, 893 fewer than the Mississippi middle of 1,192. Chill is what tells a fruit tree its dormancy is over, and it is set by climate rather than by anything you can build.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Harrison County
Across Harrison County, the ground is predominantly Ultisols, where Poarch, Smithton, and Harleston are the most extensive named soil series. The soil is generally well drained with a fine sandy loam surface. Topsoil pH runs about 4.9–5.0, very strongly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Ultisols
Drainage
Well drained
Prime farmland
41%
Hydric soils
26%
Soil still varies lot by lot — soil types explained.
How the ground varies across Harrison County
The USDA soil survey maps 42% of Harrison County as well drained — but another 54% drains differently: 22% moderately well drained, 15% poorly drained.
Poarch is the most extensive named soil at 29% of mapped acres, then Smithton (10%) and Harleston (9%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Harrison County
Each reading below is measured for Harrison County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Harrison County are well drained, in hydrologic group B — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Harrison County runs about pH 4.9–5.0, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Wet ground
MeasuredAbout 26% of Harrison County is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredHarrison County runs about 309 days between hard freezes — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
The kind of country Harrison County is in
Harrison County spans 2 EPA Level III ecoregions — Southeastern Plains (65%) and Southern Coastal Plain (35%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Harrison County
We scored all 1,086 plants against Harrison County's own USDA zone 9a and its own 309-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Mississippi profile.
Is it too late to plant in Harrison County?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Jan 7; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 4 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 10 — long-season crops need about 90 days of runway, quick greens only 30. In a climate this gentle, “too late” hardly applies — the question becomes which crops prefer the cooler months ahead.
Documented around Harrison County
- monarch butterfly5 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Harrison County
USGS estimates 972 lb of 2,4-d on Harrison County farmland in 2019, its largest by weight, ahead of Triclopyr (426 lb) and Glyphosate (221 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Harrison County — and how to grow with it.
We checked the federal record across Harrison County — 1,322 documented sites across 6 of the 9 source types we track.
The most significant on record: 12 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Harrison County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Harrison County
Closest first, across Harrison County. Listing isn't leaking, and distance isn't exposure.
- Gpt VortacUnderground Storage Tanks · 1900 ft
- SAIA MOTOR FREIGHT LINEBrownfields · 2300 ft
- Gpt Atct Control TowerUnderground Storage Tanks · 0.5 mi
- Coastal Energy Company Of MSUnderground Storage Tanks · 0.5 mi
- Highway 49 Chevron #12Underground Storage Tanks · 0.6 mi
- COASTAL ENERGY WHOLESALE TIRESBrownfields · 0.6 mi
- PHILLIPS BUILDING SUPPLY OF GULFPORTBrownfields · 0.6 mi
- Northwest Airlines IncUnderground Storage Tanks · 0.6 mi
- Race Way #674/6736Underground Storage Tanks · 0.6 mi
- BUTCH OUSTALET INCBrownfields · 0.6 mi
- Gulfport Biloxi Regional AirportUnderground Storage Tanks · 0.6 mi
- 047L0683 HARRISONNitrate · 0.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Harrison County's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Harrison County.
Sources Checked
across Harrison County
Severity Distribution
across Harrison County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Harrison County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Harrison County average
Your land is one point inside Harrison County
Everything above resolves to Harrison County as a whole — one PHZM band and one county frost record, read across 367K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at county scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better county average.
Your Lot vs the Harrison County Average
Harrison County Average
- ●USDA Zones 9a, averaged across Harrison County
- ●One soil character for all of Harrison County
- ●Frost dates read at Harrison County's scale: Feb 4 to Dec 10
YOUR Parcel
- ✓Your exact zone, not Harrison County's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Harrison County
Pull a site-specific report for your exact address in Harrison County, Mississippi — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Harrison County averages can't show:
We read public map data around Harrison County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Harrison County average
How we know this about Harrison County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Harrison County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Harrison County
When does frost risk typically end in Harrison County?
The last hard freeze (28°F) in Harrison County typically lands around Feb 4, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Feb 25.
How long is the growing season in Harrison County?
Measured between 28°F hard freezes, Harrison County sees about 309 frost-free days — roughly Feb 4 through Dec 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 25 to Nov 26, about 274 days.
Is the soil safe to grow vegetables in Harrison County?
The federal record around Harrison County is a meaningful one — 1,322 documented sites, mostly Underground Storage Tanks entries (525), the nearest Underground Storage Tanks record about 0.4 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
Everything above is measured at Harrison County's scale — its 9a band and its 309-day season. Your yard writes its own version of Harrison County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Mississippi's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Harrison County’s own scale
9 of the readings below were taken at Harrison County's own scale — its own ~309-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,322 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Harrison County's own USDA hardiness band, zones 9aUSDA PHZM 2023
- Harrison County's own 28°F hard-freeze dates and its ~309-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Harrison CountyUSDA NRCS SSURGO
- 1,322 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.4 miles outFederal environmental registers
- Harrison County's boundary and the 367,136 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~309-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Harrison County spans, Southeastern Plains the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Harrison County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Harrison County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Mississippi grower plans around — written at state scale, so they stay on the state guidefrom Mississippi
What this page can’t tell you
- How the season shifts across Harrison County — the ~309 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Harrison County's 367,136 acreswhy one lot differs from the next →
- Which of those 1,322 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Harrison Countyread your own land →