Hawthorn (May) blossom

Window

Typical: 01 May – 31 May (2026)

Latitude range

50-52°N

Coincides with hawthorn fly. 'Ne'er cast a clout till May be out' — May = hawthorn.

Relevance to fishing

The single most useful folk-wisdom signal in coarse fishing: hawthorn in flower = hawthorn fly on the water = mayfly within three weeks = tench spawning within five.

Phenology chain

Triggered by

• Blackthorn blossom typically 28d before (range 21 – 40d)

Triggers

• Hawthorn fly roughly concurrent (range -3 – 7d)
• Mayfly main hatch typically 21d after (range 14 – 35d)