Doi Mae U Kho

Doi Mae U Kho rises above Khun Yuam in southern Mae Hong Son, and for about three weeks from mid-November the slopes turn solid yellow with bua tong - Tithonia diversifolia, the Mexican sunflower - flowering across hundreds of rai of hillside. The province runs a festival around it and the road fills with Thai visitors, buses and stalls for the duration. It is worth being clear about what the flower is: Tithonia is not native, it was introduced to Thailand and has naturalised aggressively, spreading along disturbed ground and roadsides and crowding out native vegetation, so what looks like a natural spectacle is a highly successful invasive doing what invasives do. That does not make it less striking. Outside the flowering window there is a mountain road and a view. The road up is steep and busy in season, viewpoints are crowded, and Hmong villages on the slopes sell food and crafts.

What you actually see

• The bua tong bloom - Mexican sunflower covering the slopes for about three weeks.
• The festival - stalls, buses and crowds through the flowering window.
• The Hmong villages - communities on the slopes below the viewpoints.
• The invasive story - a naturalised non-native producing the whole spectacle.

When to go

Mid-November to early December, and only then - outside that window there is nothing to see. The exact peak shifts each year; check local reports.

Honest expectations

A three-week window, heavily crowded, with traffic on a steep road. The flower is an introduced invasive rather than native flora. Nothing to see outside the season.

Nearby

Khun Yuam is west; Mae Hong Son town is north.