Unlikely — Zone Mismatch
triffid weed (zones 10-12) does not overlap with District of Columbia's zone range (7b-8a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Triffid Weed is hardy to zone 10, and the warmest ground in District Of Columbia is zone 8 — 2 zones short. Planted in open ground it will not survive a District Of Columbia winter. To grow it here, grow triffid weed under glass — a greenhouse is the only lift this wide the engine models.
A greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 10-12 (plant) against 7-8 (District of Columbia). Lift modeled by crop_engine Sprint 20B effective_zone_modifier (+2 zones) via api/fast_sections.py Unlock Engine v2.
Your yard isn't the whole zone.
District of Columbia spans zones 7b-8a, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score triffid weed against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Triffid Weed Needs
- USDA Zones: 10-12
- Sun: Full Sun
District of Columbia Has
- USDA Zones: 7b-8a
- Last Hard Freeze (28°F): Mar 15
- First Hard Freeze (28°F): Nov 24
- Annual Rainfall: 39-43 inches
- Common Soils: Urban fill, Silt loam, Clay loam
Plant Zone Range (zones 10-12)
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 Triffid Weed in District of Columbia
The frost window
Across District of Columbia, the last spring hard freeze (28°F) clears between Mar 15 and Mar 15, and the first fall hard freeze lands between Nov 24 and Nov 24 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 254-day window you can count on — up to 254 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.
Winter standing
District of Columbia runs as cold as USDA zone 7, and no sourced winter-hardiness floor is on record for triffid weed, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether triffid weed is a permanent planting or a replant-every-spring crop for you turns on your own zone within District of Columbia; check its hardiness range against that before treating it as long-lived ground.
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.
Soil + Drainage Fit
Triffid Weed tolerates a wide pH range (pH 4-7.5) — 3.5 units, acid ground through alkaline — so soil acidity is rarely what limits it in District of Columbia. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 5 and 6.5 — worth knowing before you decide whether a District of Columbia soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your District of Columbia site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
District Of Columbia's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Triffid Weed needs about 19 inches of workable depth, so it is that horizon — not the surface — you are testing for. That map unit, not the state average, decides how triffid weed performs.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. District of Columbia soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Triffid Weed in District of Columbia — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 10-12 (USDA PLANTS Database)
- State Zones: 7b-8a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Mar 15 to Nov 24 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Triffid Weed in District of Columbia
Zone compatibility tells you about winter cold survival — but District of Columbia growers also need to think about:
Dense urban siting means small lots, compacted fill soils, and limited sun
Summer heat and humidity promote fungal diseases
The urban heat-island effect pushes summer temperatures above surrounding suburbs
Growing triffid weed here specifically
Triffid Weed wants pH 4.0–7.5 and rates to USDA zones 10–12, but District Of Columbia's soils are dominantly silt loam — the fit is decided by your parcel's own map unit, not the state average.
Match triffid weed to your parcel's SSURGO map unit — test pH and texture, and amend toward its 4.0–7.5 range. How to handle it →
What to actually do about these — and the constraints that apply to every District of Columbia grower, not just triffid weed — is covered on the District of Columbia growing guide.
Pollinator + Wildlife Value
Triffid Weed 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, triffid weed can only work that bloom inside District of Columbia's frost window — roughly 254 days, opening after the last 28°F freeze (Mar 15) and closing at the first (Nov 24), per NOAA Regional Climate Centers ACIS, 1991-2020.
Good to Know Before You Plant Triffid Weed
Triffid Weed is listed as toxic to dogs, cats (all) at a mild level (Cornell). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
District of Columbia Cooperative Extension
For District of Columbia-specific cultivar recommendations, planting calendars, and pest pressure for triffid weed, the canonical source is UDC Center for Urban Agriculture. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Triffid Weed native to District of Columbia?
Triffid Weed is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in District of Columbia. It can still earn a place in a District of Columbia garden — the zone comparison above tells you whether it will thrive.
Looking for plants that belong here? The District of Columbia 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 Triffid Weed in District of Columbia
When can I plant Triffid Weed in District of Columbia?
District of Columbia's last spring hard freeze (28°F) clears between Mar 15 and Mar 15, and the first fall hard freeze lands between Nov 24 and Nov 24 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Triffid Weed, so this page does not state whether it overwinters in District of Columbia and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Triffid Weed grown in across District of Columbia?
District of Columbia spans USDA hardiness zones 7b-8a (USDA ARS PHZM 2023). Triffid Weed carries a range of zones 10-12, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical District of Columbia site have?
A typical District of Columbia site sees ~254 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Triffid Weed should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Triffid Weed native to District of Columbia?
Triffid Weed is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in District of Columbia. It can still earn a place in a District of Columbia garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Triffid Weed in District of Columbia?
Triffid Weed tolerates pH 4-7.5 and well (dry spells) drainage (FAO ECOCROP). That is a 3.5-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a District of Columbia site — amend for drainage and organic matter first.
Will Triffid Weed actually grow on my specific land in District of Columbia?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores triffid weed 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 District of Columbia
State-level data is a sketch. Your Growable Ground report scores triffid weed against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that District of Columbia triffid weed averages can't show:
We read public map data around District of Columbia — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the District of Columbia triffid weed average
Explore More
Growing guides for triffid weed
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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