Uncover the secrets of medicinal herbs at the Plant Conservatory during Heritage Days 2026.

A few kilometres south of Paris, one of the region’s most striking open‑air pharmacies is on display. For the Heritage Days 2026, the National Conservatory of Plants in Milly-la-Forêt in Essonne invites you to a surprisingly nature-filled outing. Every September, this cultural event swings wide the doors to must-see or little-known spots across Paris and the entire Île-de-France, allowing everyone to explore the region’s treasures for free or at a generous concession. On 19 and 20 September 2026, set your compass for this botanical flagship and uncover the mysteries of our living heritage.

A millennia-old tradition of medicinal culture in Essonne

Milly-la-Forêt owes its botanical renown not to chance. Since medieval times, monks cultivated medicinal herbs in the gardens of local priories, taking advantage of a mild microclimate and sandy soils that favored growth. Local legends suggest that certain peppermint varieties grown there possess tonic virtues superior to those of their European cousins. The Conservatory was established in 1987 to preserve this horticultural memory and to safeguard the genetic diversity of endangered plants.

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A scientific and sensory sanctuary devoted to useful herbs

Today, the site brings together more than 1,500 species of useful plants—medicinal, aromatic, dyeing, and textile uses. The conservatory’s mission centers on agricultural research, the preservation of heirloom seeds, and public education. As you wander the themed plots, you’ll travel from tropical greenhouses to rustic allotments, awakening your senses with the scents of absinthe, chamomile, and verbena.

The 2026 Heritage Days program at the National Plant Conservatory in Milly-la-Forêt

• Animation Booth "Mission Trees! Investigating a Living Heritage"

  On the occasion of the European Heritage Days, embark on a journey to discover trees and their vital role in our environment. Through challenges, observations, and small experiments, explore the connections between trees, biodiversity, and human activity.

  This interactive activity invites everyone to observe, handle, experiment, and exchange about the richness of plant heritage.

  During the day, two guided walks are on the program at 2:00 PM and 4:00 PM (details on the event's Open Agenda guided walk).

  Participation terms: Discounted entry €6.50. Free for children up to 12, Millacois residents, teachers, journalists, and the Essonne Fan Pass. Free activities and guided walk. - Special rate | No reservation required

  Hours: Saturday, September 19, 2026 — 1:30 PM to 6:00 PM

• Guided walk: Discovering our plant heritage

  Embark on a journey through the Conservatoire's plant heritage as you stroll through the gardens. Plants, stories, uses, know-how and anecdotes will help you see these species—part of our heritage—in a new light.

  Also drop by our activity stand "mission arbres, enquêter sur un patrimoine vivant" for the whole afternoon. Info on the event on OpenAgenda.

  Participation terms: Reduced admission €6.50. Free for children up to 12, Millacois residents, teachers, journalists, Essonne Fan Pass holders. Guided walk and activities are free. - Special rate | No booking required

  Hours : Saturday, September 19, 2026 — 2:00 PM–2:45 PM, 4:00 PM–4:45 PM

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