Yellow Daylily

Basic Information

Common Name: Yellow Daylily
Scientific Name: Hemerocallis lilioasphodelus
Native Habitat: Primarily Eastern Asia, including China, Korea, and Japan. Widely naturalized in temperate regions across Europe and North America.

History / Discovery / Cultivator

The story of the daylily, particularly species like Hemerocallis lilioasphodelus, is deeply intertwined with centuries of cultivation in Eastern Asia long before Western botanists formally described it. Daylilies, known for their vibrant, fleeting blooms and resilient nature, have been cherished in gardens for aesthetic beauty and, in some cases, culinary uses (buds are edible) for millennia in countries like China.Hemerocallis lilioasphodelus, often referred to as the Lemon Lily or Yellow Daylily due to its bright yellow, fragrant flowers, is considered one of the oldest and most historically significant species within the genus. Its precise discovery date in the Western world is difficult to pinpoint, as plants and knowledge traveled along ancient trade routes. However, the genus Hemerocallis was formally named by the father of modern taxonomy, Carl Linnaeus, in his seminal work Species Plantarum in 1753. H. lilioasphodelus was one of the species included in his initial description, indicating it was known to European botanists by that time, likely introduced through botanical exchanges or exploration in Asia.While Linnaeus provided the scientific nomenclature, the cultivation and popularization of this specific species predate his work by centuries in its native lands. Early Chinese texts describe daylilies and their use, showcasing a long history of selection and propagation by countless unnamed gardeners and cultivators.In the Western world, the popularization of Hemerocallis accelerated in the 19th and 20th centuries. Species like H. lilioasphodelus became foundational parents in extensive hybridization programs. Horticulturalists like Dr. Arlow Burdette Stout, often considered the “father of modern daylily breeding” in the United States during the early to mid-20th century, utilized species like H. lilioasphodelus to develop new cultivars with improved traits, colors, and bloom cycles. Its strong constitution, pleasant fragrance, and clear yellow color made it a valuable genetic resource.Today, while countless complex hybrids exist, Hemerocallis lilioasphodelus itself remains a beloved garden plant, appreciated for its historical significance, reliable performance, late spring to early summer blooms, and sweet fragrance, standing as a testament to its enduring appeal across cultures and centuries of cultivation. Its journey from ancient Asian gardens to a scientifically classified species and a parent in modern breeding programs highlights its important place in horticultural history.

Plant Care Summary

Category	General Requirement	Notes
Light	Full Sun to Partial Shade	Performs best with at least 6 hours of sun for abundant blooms.
Water	Moderate/Regular	Prefers consistently moist soil, especially during flowering season, but is drought-tolerant once established.
Humidity	Average	Tolerant of a wide range of humidity levels.
Temp. Range	Hardy (Zones 3-9)	Very cold hardy and heat tolerant within its recommended zones.
Soil Type	Well-drained	Adaptable but prefers loamy, well-drained soil. Avoid waterlogging.
Fertilizer	Moderate	Benefit from a balanced fertilizer in spring and mid-summer, but often thrives with just compost.
Toxicity	Mildly toxic if ingested	Primarily toxic to cats (potential kidney failure), causes GI upset in dogs and mild GI upset in humans.

Botanical Insights

Adaptations

Hemerocallis lilioasphodelus possesses several key adaptations that contribute to its remarkable hardiness and ability to thrive in a variety of conditions. A primary adaptation is its robust, fleshy root system and rhizomes. These underground structures store water and nutrients, allowing the plant to survive periods of drought that would kill less resilient perennials. The rhizomes also facilitate vegetative spread, enabling the plant to form dense clumps and colonize areas over time. The plant’s deciduous nature in colder climates, where foliage dies back to the ground in winter, is a survival strategy against freezing temperatures, protecting the crown and roots. Furthermore, the “daylily” blooming pattern, where each flower lasts only a single day, is an adaptation that ensures a continuous display of blooms over a period, maximizing reproductive potential through attracting pollinators sequentially. The flowers are also typically held high on scapes above the foliage, making them easily accessible to visiting insects.

Propagation Methods

The most common and easiest method for propagating Hemerocallis lilioasphodelus is by division. Daylilies naturally form expanding clumps, and these can be dug up and divided every few years, typically in early spring or fall. The clump is carefully separated into smaller sections, ensuring each section has roots and several “fans” (groups of leaves). These divisions can then be replanted directly into the garden.
Propagation from seed is also possible for H. lilioasphodelus as it is a true species. Seeds can be collected from dried seed pods after flowering. While seed propagation allows for genetic variation and can be interesting for breeding purposes, it takes longer to reach flowering maturity (typically 2-3 years) compared to division (which often flowers the first year).

Toxicology

Hemerocallis lilioasphodelus, like other daylily species, is known to be toxic, particularly to cats. Ingestion of any part of the plant (flowers, leaves, stems, roots, pollen) can cause severe and potentially fatal kidney failure in felines. Symptoms in cats can include vomiting, lethargy, depression, loss of appetite, and kidney failure signs like increased or decreased urination within hours or days of ingestion.For dogs, ingestion typically results in less severe symptoms, mainly gastrointestinal upset including vomiting, diarrhea, lethargy, and lack of appetite. While not usually life-threatening like in cats, veterinary attention is still recommended if a dog ingests daylily plant material.In humans, ingestion is generally reported to cause only mild stomach upset. However, it is always best to err on the side of caution and prevent ingestion by children and pets. Immediate veterinary care is crucial if a cat is suspected of ingesting any part of a daylily.

Common Problems

Pests:

• Aphids: Small sap-sucking insects that cluster on buds and new growth.
• Spider Mites: Tiny arachnids causing stippling on leaves, often in hot, dry conditions.
• Thrips: Small, slender insects that feed on buds, causing distortion or failure to open (“bud rot”).
• Slugs and Snails: Chew holes in leaves and flowers, especially in damp conditions.
• Daylily Gall Midge: Larvae cause swelling and distortion in flower buds, preventing them from opening.
• Daylily Rust Mite: Microscopic mites causing reddish-brown streaks and stunted growth.

Diseases:

• Daylily Rust: A fungal disease causing orange pustules on leaves and scapes, leading to premature yellowing and decline.
• Leaf Streak: A common fungal disease causing reddish-brown streaks and spots on leaves.
• Crown Rot: Fungal diseases (e.g., Southern Blight, Fusarium) causing the base of the plant to rot, leading to collapse and death. Often related to poor drainage or planting too deep.
• Root Rot: Fungal diseases affecting the roots, typically caused by excessive moisture or poor drainage.

Other:

• Lack of Flowering: Often caused by insufficient sunlight (less than 6 hours), over-fertilizing with too much nitrogen (promotes foliage over flowers), or overcrowded clumps needing division.
• Yellowing Leaves: Can be a symptom of overwatering (leading to root/crown rot), underwatering, nutrient deficiencies, or natural dieback of older foliage or after flowering.
• Browning/Mushy Crown: A sign of severe crown rot, often due to excessive moisture, heavy soil, or planting the crown too deep.
• Buds Not Opening: May be caused by thrips, daylily gall midge, or bud rot (fungal infection).

Rarity & Value

Rarity:

The species Hemerocallis lilioasphodelus itself is not considered rare. It is a widely cultivated and readily available plant, having naturalized in many parts of the world and being one of the foundational species for modern daylily breeding. Its commonality is due to its robust nature, ease of cultivation, and prolific propagation through division. Rarity in the daylily world is typically associated with specific, newly introduced, highly sought-after, or unique cultivars (hybrids), not with the wild species itself.

Value:

The market value of Hemerocallis lilioasphodelus is generally quite low compared to modern hybrid daylily cultivars. This is because it is widely available, easy to propagate, and lacks the novel color patterns, forms, or reblooming habits often found in expensive hybrids. Factors that might slightly influence the value of a specimen would primarily be the size and maturity of the clump being sold (larger, more established clumps command slightly higher prices) or its provenance if it comes from a historically significant garden, though this is less common for the species itself than for specific named cultivars. It is often sold bare-root or in standard nursery pots at very accessible price points.