FireApproved

United States / Grow / azure bluet

azure bluet (Houstonia caerulea)
Photo: (c) Tom Norton, some rights reserved (CC BY) (CC BY), via iNaturalist. Species-typical, not necessarily this cultivar.

azure bluet

Houstonia caerulea · Rubiaceae · also called Bluets · Wikipedia

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Azure bluet has a favorable fire assessment based on low North Carolina ratings and an Oregon regional recommendation.

The low rating persists through two North Carolina publications. The 2005 guide includes Houstonia caerulea in its lowest flammability category; the 2025 revision again places it in low. The two scales have different numbers of categories. The newer guide has three categories instead of four, but low remains favorable in both. NC State's Plant Toolbox corroborates it with a low-flammability tag for the same name.

Oregon State University Extension profiles the plant as bluets or Quaker ladies. It includes the perennial among fire-resistant choices suited to Willamette Valley growing conditions. The regional scope explains where that particular recommendation is intended to be useful.

Azure bluet belongs to the Rubiaceae family and is native across southeastern, northeastern, and north-central U.S. regions. The successive low ratings, Toolbox tag, and Oregon profile support its fire-resistant classification. For a gardener comparing perennials, this is consistent favorable guidance from North Carolina, complemented by the Oregon recommendation for Willamette Valley conditions.

Form
perennial
Rated in
NC; North Carolina; North Carolina / southeastern US; Oregon (Willamette Valley)
On this lot

1. Fire evidence and conditions

Fire evidence
Fire-resistant — location does not change the cited classification.
Placement evidence
2 source placement records; source schemes remain separate.
Evidence regions
NC; North Carolina; North Carolina / southeastern US; Oregon (Willamette Valley)
Typed publication scope: 2 scopes across 2 cited fire sources
  • Fire-Resistant Landscaping in North Carolina (AG-874) · Official scoped edition
    • NC; complete normalized coverage · 2025-03-26

      The complete three-table AG-874 plant list is explicitly for North Carolina and contains 202 low-, medium-, or high-flammability rows. FireApproved accounts for all source rows under its strict taxonomy and lineage rules; source scope does not establish local suitability at a particular North Carolina site.

  • Fire-resistant Landscape Plants for the Willamette Valley (EM 9103) · Official scoped edition
    • Willamette Valley (OR footprint); partial normalized coverage · 2015-02-01

      OSU Extension says EM 9103 highlights fire-resistant plants that thrive under Willamette Valley growing conditions. FireApproved publishes 172 exact owners only as valley context. The guide shares the PNW 590 lineage and is not a second independent vote or statewide site clearance.

2. Why this plant is relevant here

State distribution
Documented in AL, AR, CT, DC, DE, GA, IL, IN, KY, LA, MA, MD, ME, MI, MO, MS, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, VT, WI, WV.
Native range
Current cited native range in AL, AR, CT, IA, KY, LA, MD, MO, MS, NH, NY, TN, VA, VT, WI.
USDA hardiness
Documented range 3a–8b.

3. Legal, ecological, and broader status

How to read this page

The status above is computed from the cited rows below: independent recommendations can support a fire-resistant result, an avoid row can produce keep-away, and disagreement stays visible as conflict. Placement notes preserve each source’s own scheme rather than translating unlike rules into one scale. This is evidence about a plant, not permission to plant it in every part of the defensible space; Zone 0 remains noncombustible.

Native and introduced range evidence

These are exact U.S. botanical-area records from the cited range source. Native and introduced describe biogeographic relationship, not fire performance or planting approval. Doubtful and extinct rows stay visible but do not count as current presence.

Current native

15

exact source areas

Current introduced

0

exact source areas

Qualified

0

doubtful or extinct source rows

15 native source areas · World Checklist of Vascular Plants, version 16 v16, as of 2026-06-04
  • Alabama (AL)
  • Arkansas (AR)
  • Connecticut (CT)
  • Iowa (IA)
  • Kentucky (KY)
  • Louisiana (LA)
  • Maryland (MD)
  • Missouri (MO)
  • Mississippi (MS)
  • New Hampshire (NH)
  • New York (NY)
  • Tennessee (TN)
  • Virginia (VA)
  • Vermont (VT)
  • Wisconsin (WI)

The lossless worldwide derivative is retained once in the research corpus; object pages repeat only exact U.S. areas needed by the local lens. The JSON twin carries the same page assertions.

Plant hardiness evidence

These values describe the plant source. Your ZIP zone comes from the separate 2023 USDA Plant Hardiness Zone Map. Whole-zone values stay whole-zone, and a single unresolved value is not treated as a tolerance range. Different source boundaries stay separate: overlapping statements are compared independently, while only ranges with no shared zone are called a conflict.

Where its sources say to plant it

Placement rules below use each source's own distances or named zones, tied to its rating. They are not interchangeable with the directory's current Zone 0 guidance.

The evidence

Grouped by what each source concluded. Primary evidence rated the plant itself (a lab, field program, or original curation); corroboration compiled or republished another source's rating and resolves to its root lineage.

Recommends (4)

Corroboration (1 rows from 1 source)

Last verified 2026-08-26. JSON (CC BY 4.0)

Profiles: USDA PLANTS · GBIF · iNaturalist · Wikidata · Wikipedia · ITIS

Houstonia caerulea (Bluets). FireApproved. https://fireapproved.com/plants/houstonia-caerulea/. Last verified 2026-08-26.