Rock Island, Texas, sits in USDA hardiness zone 9a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Expect artichoke, fig, california poppy, and cabbage to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Rock Island, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Rock Island lot. 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 Rock Island — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Rock Island — the short answer
Rock Island, Texas: USDA zone 9a, about 314 days between hard freezes, across 3K acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 29
- Colorado County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 9
- Colorado County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~314
- Colorado County normal — NOAA 1991–2020, nearest to this town
- Town area
- 3K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Colorado County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Rock Island's average, not your lot's — a low corner or a tree line moves it. Against Rock Island's 314-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Rock Island
Each reading below is measured for Rock Island itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsRock Island runs about 314 days between hard freezes (read from Colorado County, the closest normal to Rock Island) — 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
Winter hardiness
MeasuredRock Island sits in USDA hardiness zone 9a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Rock Island is in
Rock Island sits in the Western Gulf Coastal Plain — EPA Level III, inside the wider Great Plains. That is read at Rock Island's own centroid rather than borrowed from Colorado County.
What Grows in Rock Island
Every plant below cleared Rock Island's own zone 9a and its 314-day season. Each card opens that plant's Texas profile. How we score.
Is it too late to plant in Rock Island?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Jan 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jan 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 9 — 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.
What's on the federal record near Rock Island
Closest first, within ~10 miles of Rock Island. Listing isn't leaking, and distance isn't exposure.
- COPANO PROCESSING HOUSTON CENTRAL GAS PLTToxics Release Inventory · 4.6 mi
- RICE CONSOLIDATED ISDUnderground Storage Tanks · 4.7 mi
- SO 6Underground Storage Tanks · 6.4 mi
- SANDY CREEK STOREUnderground Storage Tanks · 6.5 mi
- SONNTAGS SERVICE STATIONUnderground Storage Tanks · 6.6 mi
- HANSON CENTRAL AGGREGATES STAFFORDBrownfields · 6.9 mi
- ALTAIR RECYCLING FACILITYBrownfields · 7.2 mi
- ALTAIR DISPOSAL SERVICES LLC - LANDFILLBrownfields · 7.3 mi
- ARENA PLANTBrownfields · 7.3 mi
- ROUNDHOUSEUnderground Storage Tanks · 7.8 mi
- HBH TRUCKINGUnderground Storage Tanks · 7.8 mi
- WELLTECHUnderground Storage Tanks · 7.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Rock Island'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 Rock Island.
Total Sites
65
within ~10 miles of Rock Island
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Rock Island
Severity Distribution
within ~10 miles of Rock Island
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Rock Island, Underground Storage Tanks runs higher than the national average — 60 sites within ~10 miles of Rock Island. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Rock Island
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 Rock Island average
Your land is one point inside Rock Island
Everything above resolves to Rock Island as a whole — one PHZM band, read across 3K acres, with hard-freeze dates borrowed from Colorado County’s record because no 30-year normal resolves at this town’s own centroid. 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 town 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 local average.
Your Lot vs the Rock Island Average
Rock Island Average
- ●USDA Zones 9a, averaged across Rock Island
- ●One soil character for all of Rock Island
- ●Frost dates read at Rock Island's scale: Jan 29 to Dec 9
YOUR Parcel
- ✓Your exact zone, not Rock Island's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Rock Island
Pull a site-specific report for your exact address in Rock Island, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rock Island averages can't show:
We read public map data around Rock Island — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rock Island average
How we know this about Rock Island
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Colorado County’s record, because none resolves here; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Rock Island
When does frost risk typically end in Rock Island?
The last hard freeze (28°F) in Rock Island typically lands around Jan 29, 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 19.
When is the first frost in Rock Island?
The first hard freeze (28°F) in Rock Island typically arrives around Dec 9, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 25, so the watching starts about Nov 9 — about 314 days after the spring freeze cleared.
How long is the growing season in Rock Island?
Measured between 28°F hard freezes, Rock Island sees about 314 frost-free days — roughly Jan 29 through Dec 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 19 to Nov 25, about 279 days.
Is the soil safe to grow vegetables in Rock Island?
The federal record around Rock Island shows 65 documented sites, mostly Underground Storage Tanks entries (60), the nearest Toxics Release Inventory record about 4.6 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Rock Island?
From about Nov 9 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Dec 9 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Dec 9. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Rock Island's scale — its 9a band and its 314-day season. Your yard writes its own version of Rock Island's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Rock Island’s own scale
5 of the readings below were taken at Rock Island's own scale — the 3,210 acres it covers and 65 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Rock Island's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 65 documented contamination sites on the federal record near Rock Island, the closest Toxics Release Inventory record about 4.6 miles out from the town centreFederal environmental registers
- Rock Island's boundary and the 3,210 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~314-day seasonGrowable Ground crop-matching engine
- The ecoregion at Rock Island's own centroid, the Western Gulf Coastal PlainUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Rock Island has no normal of its own, so its county's is the closest measured readfrom Colorado County
- Soil character — no town-scale survey exists, so Rock Island's 3,210 acres read through its county's SSURGO summaryfrom Colorado County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Colorado County
- The growing challenges every Texas grower plans around — written at state scale, so they stay on the state guidefrom Texas
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Colorado County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Rock Island's 3,210 acreswhy one lot differs from the next →
- Which side of Rock Island you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,210 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Toxics Release Inventory record about 4.6 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Rock Island-wide figureread your own land →
More in Texas
Wider growing context
What grows across TexasRock Island sits outside our named growing regions, so Texas as a whole is its closest context here.