Indoor Ecological Garden (屋内生態園) greenhouse, Takasaki Dye Plant Garden (高崎市染料植物園)

The city says Takasaki's Dye Plant Garden was created to share Japan's dyeing and weaving culture through a theme park devoted to plant dyeing. Japanese Wikipedia lists it as a municipal garden opened in April 1994. It covers 85,183 m² behind the Kannonyama hills and combines a walk among dye plants, the dyeing craft hall (染色工芸館), which holds exhibitions and workshops, and the greenhouse.

The greenhouse is called the "indoor ecological garden" (屋内生態園). It shares a building with a rest room whose two floors are free to use. The city presents dye plants that grow wild in Okinawa alongside others used for dyeing in tropical southern Asia. The link with the rest of the garden lies in the history of dyeing told along the outdoor path: in the Muromachi and Edo periods, the city recalls, many tropical plants from southern Asia arrived and added new colours, and the greenhouse lets visitors see such plants.

A small cafe, "Yaneya" (屋根屋), run in the rest room on Saturdays, Sundays and public holidays, closed on Sunday 29 March 2026 according to a city notice updated in February; visitors may still eat a meal they bring, and the city says a new operator will be announced. Neither the city's pages nor Wikipedia give the year the greenhouse was built or the name of its designer.

The OpenStreetMap outline distinguishes, in the eastern part of the garden, two adjoining volumes of about 220 m² and 190 m², one of them tagged as a greenhouse.

Photographs show a greenhouse closed by glazed walls in light metal frames, including a sliding door in front of which a small sign warns that drops fall from the ceiling. Inside, the city's official photograph shows a lattice steel frame under a covering of clear panels; the neighbouring rest room has a sloping roof of glazed panes on a metal frame, shaded by blinds.

The plan displayed in the greenhouse shows a winding path, water features and clumps of trees divided into four zones: mountain (tall trees forming woodland), waterside (where the look of a mangrove can be observed), flowers (small flowering plants of Okinawa) and village (plants cultivated in Okinawa and foreign species).

According to the city, the greenhouse holds about twenty species of subtropical dye plants: plants that grow wild in Okinawa and plants used for dyeing in the tropical regions of southern Asia. The official pages name three through their photographs, ryūkyū-ai (リュウキュウアイ), beni-no-ki (ベニノキ) and fukugi (フクギ), whose pictures show the foliage and sometimes flowers or fruit. The greenhouse plan sorts them by habitat: waterside plants near the mangrove, forest trees in the mountain zone, small flowering plants in the flower zone, and plants cultivated in Okinawa together with foreign species in the village zone. A visitor also reports a nepenthes (ウツボカズラ), a carnivorous plant of the mountains of Southeast Asia.

The greenhouse stands in the eastern part of the garden, about a hundred metres from the dyeing craft hall, on the dye-plant path that visitors follow from the entrance, according to one visitor; it extends the walk among dye plants, whose sections follow the Asuka-Nara, Heian-Kamakura and Muromachi-Edo periods and the modern era, with over thirty species each. According to the city's signs, indigo (アイ) and murasaki (ムラサキ) bloom in June, safflower (ベニバナ) in July. Drops fall from the ceiling inside the greenhouse, so delicate clothing is best left behind. The neighbouring rest room offers somewhere to sit and eat a packed meal. By public transport, the Guruirin "Kannonyama" loop bus stops at Senryō-shokubutsuen-iriguchi; by taxi, Takasaki station is about fifteen minutes away.