Euphrasia rostkoviana, commonly known as eyebright or sticky eyebright, is a semi-parasitic annual herb native to Europe and the Mediterranean region. It exhibits physiological dormancy requiring cold stratification to initiate germination, typically needing exposure to temperatures around 5°C. Seeds should be sown on the surface of moist, well-drained soil in proximity to suitable host plants such as grasses, as the species depends on root parasitism for vigorous growth and flowering.
Before sowing
Cold stratification recommended to break physiological dormancy; sow in autumn or spring after stratification
Sowing
What to expect
Tips
Sow seeds in autumn (October-November) or spring (March-April) after cold stratification. Seeds can be sown on damp filter paper or blotting paper and refrigerated. Germination may be variable and slow, taking up to 10 weeks; germination rates as low as 10-20% are common. Plant near compatible host grasses (Poa annua, P. nemoralis, Agrostis species) for best results. Keep soil consistently moist but not waterlogged. Do not fertilize heavily as this increases competition with hosts. Avoid overly compact soil. Seeds retain viability for extended periods but decline over time in storage.
Sources: Yeo (1964, 1962) BSBI studies on Euphrasia germination and cultivation; Neidhardt (1947) cultivation experiments; European Medicines Agency Euphrasia monograph; Botanic Gardens horticultural protocols
