Yes — Strong Match
ageratum is grown as an annual, so season length decides it here, not a winter zone — and New Jersey's typical season runs ~222 frost-free days against the ~60 ageratum needs.
Sow by about Aug 31
Ageratum is grown as an annual, so what decides it here is season length, not a winter zone. It needs about 60 frost-free days and a typical New Jersey season runs ~222 frost-free days, leaving 162 days of slack. That is room to sow as late as about Aug 31 and still finish before the usual first freeze (Nov 9), or to run a second succession.
Want more weeks at either end of that window? How to buy the weeks →
60 frost-free days required against New Jersey’s ~222-day season. NOAA Regional Climate Centers ACIS 1991-2020 (28°F killing freeze), state median across counties, via stateClimateData.ts.
Your yard isn't the whole zone.
Ageratum is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical New Jersey site runs ~222 frost-free days, but that is a state median, not your yard: slope, trees, and low spots move the last-frost date across a single parcel. Enter your address and we'll score ageratum against your land's actual frost dates, sun, and soil.
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Zone Comparison
Ageratum Needs
- USDA Zones: Data pending
- Frost-Free Days: 60+
- Sun: Full Sun
- Mature size: 1.5 ft tall
- Picking window: ~90 days of harvest
- Drought tolerance: Low
New Jersey Has
- USDA Zones: 6a-8a
- Last Hard Freeze (28°F): Mar 26 - Apr 4
- First Hard Freeze (28°F): Nov 5 - Nov 17
- Annual Rainfall: 40-50 inches
- Common Soils: Sandy loam (Pine Barrens), Silt loam, Clay
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Ageratum in New Jersey
The frost window
Across New Jersey, the last spring hard freeze (28°F) clears between Mar 26 and Apr 4, and the first fall hard freeze lands between Nov 5 and Nov 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 215-day window you can count on — up to 236 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
When to start the seed
Those dates are when ageratum goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from New Jersey's late-side last freeze of Apr 4 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Days to maturity vs. the window
At 70 days to maturity (USDA PLANTS Database), counting from the last hard freeze it ripens with 145 days to spare even in New Jersey's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Morris County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
Frost-free days
Ageratum wants 60+ frost-free days; a typical New Jersey site sees ~222 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Ageratum needs ~800 GDD (base 50°F) to ripen. The state median runs ~3340 GDD (from PRISM 1991-2020 climate normals), so New Jersey's typical season clears that easily.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Ageratum likes near-neutral soil (pH 5.5-7). That's the common-ground band across New Jersey's sandy loam (pine barrens) and silt loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 6.5 — worth knowing before you decide whether a New Jersey soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your New Jersey site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
New Jersey's soils run mostly sandy loam, but SSURGO maps the series, texture, and drainage under your exact parcel. What matters for ageratum is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how ageratum performs.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. New Jersey soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Ageratum in New Jersey — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: Data pending (USDA PLANTS Database)
- State Zones: 6a-8a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Mar 26 - Apr 4 to Nov 5 - Nov 17 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 70 days
What Else to Consider for Ageratum in New Jersey
Zone compatibility tells you about winter cold survival — but New Jersey growers also need to think about:
Sandy Pine Barrens soils are nutrient-poor
Urban heat island effects in northern NJ
Deer browse is extreme in suburban areas
Growing ageratum here specifically
New Jersey's soils run mostly sandy loam (Ultisols), and whether that suits ageratum's pH 5.5–7.0 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward ageratum's 5.5–7.0 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every New Jersey grower, not just ageratum — is covered on the New Jersey growing guide.
Timing shifts within New Jersey
New Jersey isn't one climate. In Morris County, the last hard freeze (28°F) holds until about Apr 11 — roughly 11 days later than the recorded state median — so plant ageratum to your county's window, not the statewide date.
Ageratum needs about 60 days of frost-free season to complete its cycle. Even Sussex County — New Jersey’s shortest season at 196 frost-free days — clears that by 136 days, so season length isn’t the constraint anywhere in New Jersey. What varies is your own parcel.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Ageratum's 60-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Ageratum draws honeybees, native bees, and butterflies (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, ageratum can only work that bloom inside New Jersey's frost window — roughly 222 days, opening after the last 28°F freeze (Mar 26 - Apr 4) and closing at the first (Nov 5 - Nov 17), per NOAA Regional Climate Centers ACIS, 1991-2020.
Recommended Ageratum Varieties for New Jersey
New Jersey publishes no state variety trial for ageratum, so we won't invent a "best for New Jersey" list. Choose types rated to your USDA hardiness zone (6a-8a), and confirm winter survival and drainage against your own parcel.
New Jersey Cooperative Extension
For New Jersey-specific cultivar recommendations, planting calendars, and pest pressure for ageratum, the canonical source is Rutgers Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Ageratum native to New Jersey?
No — the USDA PLANTS Database lists Ageratum as introduced rather than native in the Lower 48, so it is not part of New Jersey's native flora. It grows here as a garden plant; pairing it with a few New Jersey natives keeps local pollinators fed too.
Looking for plants that belong here? The New Jersey growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Ageratum in New Jersey
When can I plant Ageratum in New Jersey?
New Jersey's last spring hard freeze (28°F) clears between Mar 26 and Apr 4, and the first fall hard freeze lands between Nov 5 and Nov 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Ageratum mature before first frost in New Jersey?
Yes — Ageratum matures in 70 days (USDA PLANTS Database), and New Jersey's dependable hard-freeze-free window runs 215 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 145 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Ageratum grown in across New Jersey?
New Jersey spans USDA hardiness zones 6a-8a (USDA ARS PHZM 2023). Ageratum carries a range of zones Data pending, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical New Jersey site have?
A typical New Jersey site sees ~222 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Ageratum needs 60+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Morris, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Ageratum native to New Jersey?
No — the USDA PLANTS Database lists Ageratum as introduced rather than native in the Lower 48, so it is not part of New Jersey's native flora. It grows here as a garden plant; pairing it with a few New Jersey natives keeps local pollinators fed too.
How should I amend the soil for Ageratum in New Jersey?
Ageratum prefers pH 5.5-7 and well (dry spells) drainage (Growable Ground Plant Database). That sits in the common-ground band across New Jersey soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Ageratum actually grow on my specific land in New Jersey?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores ageratum against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in New Jersey
State-level data is a sketch. Your Growable Ground report scores ageratum against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that New Jersey ageratum averages can't show:
We read public map data around New Jersey — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the New Jersey ageratum average
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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