Romulea bulbocodium aka Crocus Leaved Romulea

Romulea bulbocodium is moderately challenging to cultivate, requiring specific conditions to thrive. It needs full sun, well-drained sandy soil, and a distinct summer dormancy period during which the corm must be kept completely dry. While fairly hardy (tolerating temperatures down to -10°C), it is not long-lived outdoors in climates with wet summers. In Britain and similar climates, it performs best in alpine houses or bulb frames where moisture can be controlled. In Mediterranean-type climates, it is one of the easiest Romulea species for outdoor gardens.

Water Romulea bulbocodium sparingly during its growing season (autumn through spring), allowing the soil to dry out between waterings. The critical requirement is maintaining completely dry conditions during its summer dormancy period when the foliage dies back. Overwatering, especially during dormancy, will cause the corm to rot. In outdoor cultivation, natural winter rainfall in Mediterranean-type climates is usually sufficient during the growing season.

Romulea bulbocodium requires very well-drained, sandy soil that mimics its natural coastal and rocky Mediterranean habitat. The soil should be light and gritty to prevent waterlogging. It tolerates a range of pH levels from mildly acidic through neutral to mildly alkaline. Adding coarse sand or grit to heavier soils improves drainage. In containers, a free-draining alpine or bulb compost mixed with additional grit works well.

Romulea bulbocodium requires full sun and cannot tolerate shade. In its native Mediterranean habitat, it grows in exposed, sunny positions in coastal areas and rocky ground. The flowers have an interesting behavior: they only open from midday to early evening, remaining closed during morning hours. Insufficient light will result in poor flowering and weak growth.

Romulea bulbocodium is fairly hardy, tolerating short periods of temperatures down to approximately -10°C (14°F), making it suitable for USDA zones 6-9 and UK hardiness zone 7. It thrives in Mediterranean-type climates with mild, wet winters and hot, dry summers. The plant is dormant during summer and actively grows in the cooler months from autumn through spring. In areas with cold, wet winters, protection from excessive moisture is more important than protection from cold.

Romulea bulbocodium can be propagated by seed or division. For seed propagation, sow fresh seeds in spring in a greenhouse using good loamy compost at 3-4mm depth. Keep them cool and prevent drying out. For division, separate offset corms during late summer when the plant is dormant, ensuring each division has a growing point. Plant immediately in well-draining soil and water sparingly until growth resumes.

Romulea bulbocodium produces its crocus-like flowers from February to May, depending on climate. The blooms are among the largest in the Romulea genus, with six tepals typically in shades of bluish-lilac to violet, featuring a distinctive yellow centre. The flowers measure 2-5.5 cm in length. Each bloom lasts approximately three days and has the fascinating habit of opening only from midday to early evening, closing during morning hours. White and yellow varieties also exist, including the alba form and var. crocea.

Romulea bulbocodium is a hermaphrodite species (having both male and female organs) and is pollinated by insects. The flowers provide valuable nectar and pollen for bees and other pollinating insects. A distinctive feature of the flower is that the stigma overtops the stamens, which may help promote cross-pollination. The midday-to-evening flowering habit coincides with peak insect activity in its Mediterranean habitat.

Romulea bulbocodium is a compact, slow-growing cormous plant reaching just 15-20 cm (6-8 inches) in height with a spread of about 10 cm (4 inches). It produces slender, grass-like basal leaves measuring 5-30 cm long that may be curved or straight. The small underground corm reaches up to 3 cm in diameter. Growth occurs primarily during the cooler months from autumn through spring, with the plant becoming dormant during summer.

Romulea bulbocodium is native to the Mediterranean region, with a distribution extending from Morocco and Portugal in the west to Syria in the east, and south to Sudan. In Europe, it occurs in Spain, Portugal, France (including Corsica), Italy (including Sardinia and Sicily), Greece (including Crete), the former Yugoslavia, and Bulgaria. It also grows in North Africa (Algeria, Morocco, Tunisia) and the Middle East (Israel, Jordan, Lebanon, Turkey). The species grows in sandy and rocky coastal habitats, scrubland, and exposed rocky ground up to 1000 metres elevation.

Romulea bulbocodium follows a Mediterranean growth cycle opposite to many common garden plants. In autumn, as temperatures cool and rains begin, new growth emerges from the dormant corm. During winter and early spring, water moderately and ensure full sun exposure. Flowering occurs from February to May. As summer approaches and foliage yellows and dies back, reduce watering completely. During summer dormancy (June-September), the corm must remain completely dry. Resume light watering when new growth appears in autumn.

Romulea bulbocodium can grow outdoors in USDA zones 6-9 (UK zone 7), tolerating temperatures down to -10°C. It thrives in Mediterranean-type climates and is considered one of the best Romulea species for outdoor cultivation in suitable areas. However, in regions with wet summers like Britain, it is not long-lived outdoors and performs better in alpine houses, bulb frames, or cold greenhouses where summer moisture can be controlled. Choose a sunny, well-drained position with sandy soil. In colder climates, a protective mulch can help overwinter the corms.

Several varieties and forms of Romulea bulbocodium are recognized. Var. bulbocodium is the typical form with bluish-lilac flowers and yellow centre. Var. crocea from Turkey and Syria produces yellow flowers and grows in sandy soils. Var. leichtliniana from Crete shows distinctive colorful tepal backs. An alba form produces pure white flowers without any colour on the tepal backs. The species exhibits considerable natural variation in flower colour and size across its wide Mediterranean range.

Repot Romulea bulbocodium every 2-3 years or when the corms become crowded in their container. The best time to repot is during the summer dormancy period when the plant has no active growth. Use fresh, well-draining compost mixed with plenty of coarse sand or grit. Plant corms about 5-8 cm deep. Ensure the new container has excellent drainage holes. After repotting, keep the soil dry until new growth emerges in autumn.

The corm of Romulea bulbocodium is edible and has been traditionally eaten by shepherds in the Mediterranean region. Though small (up to 3 cm in diameter), it is described as very tasty with a pleasant nut-like flavour, making it a delicious wayside nibble. Useful Temperate Plants rates its edibility at 4 out of 5, while PFAF gives a more conservative rating of 1 out of 5, likely reflecting the limited quantity available from the small corms.

Romulea bulbocodium is relatively trouble-free when grown in appropriate conditions. The main concern is rot caused by excessive moisture, particularly during summer dormancy. Ensuring excellent drainage and keeping corms dry during dormancy prevents most fungal problems. Slugs and snails may occasionally damage emerging foliage in spring. In containers, vine weevil larvae can damage corms. Good hygiene and appropriate watering practices are the best preventive measures.

The toxicity level of this plant has not been officially confirmed by Ploi. If there is a possibility of ingestion of plant material with an uncertain toxicity by you, a family member, or a pet, it is advisable to seek the assistance of a medical professional.