Botanical Name: Calylophus berlandieri

Common Name: Calylophus, Berlandier’s Sundrops, Square-Bud Primrose

Synonyms: Calylophus berlandieri subsp. Berlandieri

Category: Ground Cover

Family: Onagraceae

Lifecycle: Perennial

Lifecycle (Alt): Annual

USDA Symbol: CABE4

Hardiness Zone North: 5A

Hardiness Zone South: 9B

Sun Requirement: Full Sun (6+ hours)

Sun Requirement (Alt): Partial Shade (2-4 hours)

Water Requirement: Low

Growth Rate: Moderate

Maintenance: Low

Plant Adult Height: 12-18 in

Plant Adult Spread: 18-24 in

Plant Spacing: 12-18 in

Soil Preference: Sandy Loam

Soil pH Preference: Slightly Alkaline (7.4 – 7.8)

Propagation: Seed, Stem Cutting

Attracts: Bees, Birds, Butterflies, Hummingbirds, Moths

Resists: Rabbit, Deer, Disease

Tolerates: Freeze, Drought, Clay Soil, Shallow Rocky Soil, Dry Soil, Heat

Miscellaneous: Tolerates Poor Soil, Wildflower, Native Plant

Description: Calylophus, botanically known as Calylophus berlandieri, is a perennial plant native to North America with bright yellow blooms that exude a delicate appeal. Its elongated flowers open primarily during the late afternoon and are known for their crepe-like texture. A distinguishing feature is their ability to fade to an orange or pink hue as they age, adding a subtle shift in color to gardens. Calylophus thrives in well-drained soil and is widely recognized for its drought tolerance, making it an excellent choice for xeriscaping or low-water gardens. The plant is resilient under extreme conditions, including heat and poor, rocky soils. Calylophus is not prone to invasiveness and poses no significant threats in terms of toxicity, as it is non-toxic to both humans and pets. The plant blooms profusely in spring and can continue to offer sporadic flowers through the summer months and into the fall. Its flowers attract a variety of pollinators, featuring prominently in butterfly and bee gardens where it supports the local ecosystem. While its low-growing habit allows it to serve well as a ground cover, Calylophus should be positioned with ample sunlight for optimal growth and blooming. Its tolerance for heat and arid conditions makes it an ideal candidate for regions that experience prolonged periods of warmth. The vibrant flowers of Calylophus bear a striking resemblance to those of the evening primrose, a close relative, but its lower stature and adaptability to drier conditions set it apart. Calylophus offers versatility in landscape design, whether it is used to add color to rock gardens, borders, or as part of native plantings. Regularly caring for the plant involves minimal yet essential upkeep, keeping it trimmed to encourage a bushier form while preventing it from becoming leggy.

 Propagation & Planting: To plant Calylophus, choose a location with full sun and well-drained soil. Begin by loosening the soil to a depth of 12 inches, and mix in organic matter such as compost to improve soil fertility and drainage. Dig a hole twice as wide and as deep as the plant’s root ball. Carefully remove the plant from its container, gently tease out any encircling roots, and set it in the hole at the same depth it was growing in the container. Backfill with soil, firming gently to remove air pockets. Water the plant thoroughly to settle the soil around the roots. Mulch around the base to conserve moisture, leaving a gap around the stem to prevent rot. If propagating Calylophus, you can use seeds or cuttings from non-proprietary species. For seed propagation, sow seeds indoors in a well-draining mix 6-8 weeks before the last frost date, barely covering them with soil. Transplant seedlings outdoors after the danger of frost has passed. For cuttings, take 3-4 inch stem cuttings in spring or early summer, remove lower leaves, dip in rooting hormone, and plant in a moist rooting medium covered with a plastic bag to maintain humidity until roots develop.

Plant Care: Calylophus requires well-drained soil with a sandy or gravelly texture to thrive, as it is drought-tolerant and does not perform well in water-logged conditions. Position the plant in a location where it will receive full sun, as it needs at least six to eight hours of direct sunlight daily for optimal growth. Water Calylophus sparingly, allowing the soil to dry out between waterings; excessive moisture can lead to root rot. Fertilization should be minimal; a light application of a balanced fertilizer in early spring should suffice. Pruning can be beneficial to encourage denser growth and remove any dead or spindly stems, ideally done in late winter or early spring. Mulching around the base helps to retain moisture and control weeds, though care should be taken to avoid direct contact with the plant’s stems. Calylophus is generally low-maintenance and resistant to most pests and diseases, but keeping the surrounding area free of debris and ensuring good airflow can help prevent any potential issues.

Fertilize: Calylophus thrives in well-drained, infertile soils and generally does not require fertilization for healthy growth. This plant is adapted to thrive in areas with poor soil nutrient levels, and over-fertilizing can lead to decreased flowering and leggy growth. If the surrounding soil is exceptionally poor or if you wish to enhance blooming slightly, a light application of a balanced, slow-release fertilizer, such as one with an NPK ratio of 10-10-10, can be applied sparingly in early spring. Avoid fertilizing during the summer months, as excessive nutrients can harm the plant. Additionally, mulch or organic matter can be added to the soil annually to improve its organic content without relying on chemical fertilizers. Always apply fertilizers conservatively to prevent root burn and ensure that the natural growth habits of the Calylophus are maintained.

Prune: To maintain the health and vigor of Calylophus, prune it in early spring before new growth emerges. This timing allows the plant to recover quickly and focus energy on developing fresh growth. Remove any dead, damaged, or diseased stems, cutting them back to healthy tissue or to the plant’s base. Trim back any leggy or unruly growth to shape the plant and encourage bushier growth. Cut just above a leaf node to promote branching. Avoid pruning during late fall or winter, as this can stress the plant during its dormant period and may lead to damage from cold weather. Also, refrain from heavy pruning in late summer to avoid stimulating new growth that may not harden off before cooler temperatures arrive. Regular light maintenance throughout the growing season can also help keep Calylophus tidy but limit this to deadheading spent blooms.

Pest & Disease:  Calylophus is susceptible to a few pests and diseases that require careful monitoring and management. Common pests include aphids, whiteflies, and spider mites, which can cause damage by sucking sap and potentially transmitting diseases. Regularly inspect the foliage for these insects, and if detected, use insecticidal soap or horticultural oil as treatment. Ensure applications target the undersides of leaves where these pests often reside. For disease management, Calylophus may be affected by root rot and powdery mildew. To prevent root rot, provide well-drained soil and avoid overwatering. Powdery mildew appears as a white, powdery coating on leaves and can be managed by ensuring good air circulation around the plant and applying a fungicide if necessary. Removing infected plant parts can also help reduce disease spread. Maintaining a balance of proper sunlight and monitoring watering practices will significantly aid in preserving the health and vigor of Calylophus, reducing its susceptibility to common pests and diseases.

Attribution:  This plant information is the copyrighted property of PlantTAGG, Inc. (www.planttagg.com) and is published with permission.

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