Sulphurflower Buckwheat (Eriogonum umbellatum) is a perennial plant that is tolerant of cold heat and drought conditions. Its gray foliage makes an interesting backdrop for showy yellow flowers that bloom in summer. An excellent ground cover especially for poor soil conditions it grows in full sun to partial shade.
I. Appearance and Characteristics
Eriogonum umbellatum is a species of wild buckwheat known by the common name sulphurflower buckwheat, or simply sulphur flower. It is native to western North America from California to Colorado to central Canada, where it is abundant and found in many habitats, including the sagebrush steppe and alpine areas.
It is an extremely variable plant and hard to identify because individuals can look very different from one another. Also, there are many varieties. It may be a perennial herb blooming by summer with stems 10 centimeters (4 in) tall and two to six clusters of flowers, with a whorl of leaves below the stems, or a sprawling shrub approaching 2 meters (6+1⁄2 ft) high and wide. The leaves are usually wooly and low on the plant, and the flowers come in many colors from white to bright yellow to purple.
It is a popular larval host, feeding the bramble hairstreak, desert green hairstreak, lupine blue, Mormon metalmark, Rocky Mountain dotted blue, Sheridan’s hairstreak, Sonoran metalmark, and western green hairstreak. Additionally, goats and domestic sheep feed on the plant.
The wildflower gardening author Claude A. Barr complemented sulphurflower buckwheat as a “treasure in appearance and in adaptation in my garden.” It is valued for its very low water usage for xeriscaping. The cultivar “Kannah Creek”, a selection of Eriogonum umbellatum var. aureum, has been introduced to the garden trade by the Plant Select cooperative sponsored by Colorado State University and Denver Botanic Gardens. It grows in USDA zones 4–8.
II. How to Grow and Care
Sulphurflower Buckwheat thrives in well-draining soils and requires full sun to flourish, making it a low-maintenance option for gardeners. Key special care points include minimal watering once established, as sulphurflower Buckwheat is drought-resistant, and avoidance of heavy, wet soils to prevent root rot. These factors contribute to sulphurflower Buckwheat having an easy care difficulty level.
Sunlight and Soil
Sulphurflower Buckwheat performs best in full sun, in dry to medium, well-drained soils. It needs low amounts of summer irrigation. This plant tolerates drought, poor soils, rocky soils, and high heat.
Watering
Adapted to the dry conditions of its native mountainous regions, sulphurflower Buckwheat thrives with minimal moisture and has evolved a notable drought tolerance. With an affinity for well-drained soils, sulphurflower Buckwheat maintains a balance between hydration and drainage, requiring watering every week to sustain its health without oversaturation. Typically grown outdoors due to its hardy nature, sulphurflower Buckwheat is particularly adept at conserving water within its tissues during the growing season, ensuring survival in varying climate zones.
Fertilizing
For optimal growth, sulphurflower Buckwheat benefits from balanced nutrition fertilizers, albeit sparingly, as it’s adapted to low-fertility soils. Fertilization should be limited to once in early spring with a high-phosphorus mix to encourage vibrant blooms; too much can harm sulphurflower Buckwheat’s natural hardiness. Use no more than a tablespoon per plant, ensuring even distribution. Periodic evaluations will help adjust the regimen as sulphurflower Buckwheat matures or if seasonal changes dictate. Careful application is key to avoid root burn.
Propagation
Eriogonum umbellatum is almost always propagated by seeds because the mature plants are nearly impossible to divide, or even transplant, due to their long taproots.
However, growing sulphur buckwheat plants from seeds is challenging as the germination is low.
For increasing the chances of germination, it is recommended to stratify the seeds for three months and add a thin layer of gravel or sand to the potting mix once the seedlings start to emerge.
This will help reduce damping-off, which is the major cause of seedling deaths.
The seeds are both commercially available and are manually collected from the three-sided achenes.
For those who do not know, achene is the term used for dry, single-seeded, indehiscent (remain unopened at maturity) fruit.
Transplanting
The prime time to relocate sulphurflower Buckwheat is during the vernal rejuvenation, as stable temperatures and moderate sunlight promote root establishment. Choose a bright, well-draining spot. If needed, enrich the soil slightly to support acclimation.
Pest or Diseases
The flowers of the plant are highly attractive to butterflies and serve as the larval host of many butterflies from the family Lycaenidae.
The flowers also attract bees whereas seeds of the plant attract different types of birds.
All in all, the wildflower attracts a wide range of pollinators.
III. Uses and Benefits
Since sulphurflower buckwheat plants have mat-forming growing habit, they are most widely used for ground covers.
Since they have low water requirements and attract butterflies, sulfur buckwheat plants are also highly popular for growing in rock gardens and butterfly gardens.
According to research, some Native American communities used certain parts of this plant for medicinal purposes.
However, no such use is reported in modern times.
