Mountain Bluets, Quaker Ladies, Azure Bluet

Houstonia caerulea

Family: Rubiaceae
Genus: Houstonia (hoos-TOH-nee-uh) (Info)
Species: caerulea (see-ROO-lee-uh) (Info)
Synonym:Hedyotis caerulea
Synonym:Houstonia caerulea var. faxonorum
View this plant in a garden


Alpines and Rock Gardens



Water Requirements:

Average Water Needs; Water regularly; do not overwater

Sun Exposure:

Sun to Partial Shade



Foliage Color:

Unknown - Tell us


under 6 in. (15 cm)


6-9 in. (15-22 cm)


USDA Zone 3a: to -39.9 C (-40 F)

USDA Zone 3b: to -37.2 C (-35 F)

USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

Where to Grow:

Grow outdoors year-round in hardiness zone



Bloom Color:

Light Blue

White/Near White

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Bloom Size:

Unknown - Tell us

Bloom Time:

Late Spring/Early Summer

Mid Summer

Late Summer/Early Fall

Other details:

Unknown - Tell us

Soil pH requirements:

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

Patent Information:


Propagation Methods:

By dividing the rootball

Direct sow as soon as the ground can be worked

Seed Collecting:

Collect seedhead/pod when flowers fade; allow to dry


This plant has been said to grow in the following regions:

Louisville, Kentucky

Durham, Maine

Oakland, Maryland

Billerica, Massachusetts

North Billerica, Massachusetts

Norton, Massachusetts

Roslindale, Massachusetts

Greenville, New Hampshire

Croton On Hudson, New York

Elizabethtown, New York

Keeseville, New York

Saugerties, New York

Raleigh, North Carolina

Guysville, Ohio

South Point, Ohio

Cranberry Twp, Pennsylvania

Lawrenceville, Pennsylvania

Milford, Pennsylvania

Millersburg, Pennsylvania

Wilkes Barre, Pennsylvania

Chattanooga, Tennessee

Cascade, Virginia

Lanexa, Virginia

Leesburg, Virginia

Roanoke, Virginia

show all

Gardeners' Notes:


On Apr 17, 2014, coriaceous from ROSLINDALE, MA wrote:

A lovely native plant here. I've found populations varying tremendously in size and color. The blues vary from mid-blue to nearly white, and in the same population I've found individuals that are pure white (with the yellow throat). In New England, I mostly see pale skim-milk colored flowers, and near Washington DC I mostly see them in a more saturated sky blue.

They seem to occur naturally where there's little competition, generally in small patches on acid, infertile soils in thin grass, usually accompanied by moss. I see them growing in full sun to dappled shade, often in very dry places under trees, and in the grassy verges of highways. I can't imagine that they'd survive in a dense thriving lawn, and I can't imagine them growing as a weed-suppressing ground cover. The i... read more


On Apr 16, 2014, _emily_rose from Chattanooga , TN (Zone 7b) wrote:

I love my Bluets! They appeared in the mossy areas of my lawn the first spring in my house, two years ago. They like moist shady areas, but are starting to spread out, moving to some of the sunnier and grassier areas. What started as a dotting of color in my yard the first spring is turning into a carpet of color. They begin to bloom with the first daffodils. Because of my shade, I rarely cut my grass, and I think this has helped them naturalize.


On Jan 23, 2008, Mainer from Durham, ME (Zone 3a) wrote:

These grow wild in our fruit orchards, fields, pastures here in Maine.


On Sep 12, 2004, lego_brickster from Lawrenceville, PA (Zone 5b) wrote:

These are native to our area (Zone 5), and one of the few flowers that came with the house.

They seem to thrive in the shady, damp and acidic lawn which is otherwise covered only with moss, but we have spotted them in much drier and nearly full sun locations.

We look forward to these every spring, and bloom at the same time as daffodils and other spring flowers. They can last for weeks. It is a fine sight to see your lawn awash in sky-blue flowers!
By the time the lawn starts growing, these have all but disappeared.

We don't know much yet about their propagation. We started this year by simply dividing and transplanting a clump. The flowers are so small that I have not found a seed yet. We'd love to grow more.