How to Grow Poor Man's Weather Glass (Anagallis): The Flower That Forecasts Rain

How to Grow Poor Man's Weather Glass (Anagallis)

Poor Man's Weather Glass (Anagallis monellii), also called Blue Pimpernel, Scarlet Pimpernel, or Shepherd’s Weather Glass, is a fascinating low annual (6–7 inches) whose ¼-inch flowers open in sunshine and close when rain approaches—a natural barometer! Native to Europe and North/West Africa, it’s considered a weed there but a charmer in rock gardens, borders, cottage gardens, and containers. Classified as an herb; related to primroses.

Propagation

Sow seeds indoors 4–6 weeks before last frost (use heat mat—germination is slow, 14–45 days) or directly after frost. Cover lightly (¼ inch). Transplant young plants carefully (peat pots recommended) 18–24 inches apart. Self-sows reliably.

How to Grow Poor Man's Weather Glass

• Light: Full to part sun.
• Soil: Sandy, well-drained.
• Water: Regular but not excessive.
• Fertilizer: Light feed every 6–8 weeks.
• Maintenance: Pinch tips in spring/early summer to encourage spreading.

Bloom Time

Spring and fall.

Pests & Diseases

Rarely troubled.