1 Allan Gardens Conservatory, Toronto; toronto.ca/ parks/featured-parks/ conservatories. donated to the toronto Horticultural society in 1858, this landmark has an exotic plant collection and must-see flower shows. 2 Longwood Gardens, Philadelphia; longwoodgardens.org. amid its 435 hectares, you’ll find a large 1.5hectare indoor section. From the end of January through to the end of March, take in the dazzling orchid displays. 3 Muttart Conservatory, Edmonton; edmonton.ca/ muttart. Consisting of four glass pyramids, each showcasing a different environment, the conservatory defines edmonton’s skyline. Look out for exhibits, rotating up to eight times a year. 4 Royal Botanic Gardens at Kew, England; kew.org. explore the iconic greenhouses at this Unesco World Heritage site, including the Palm House, one of the most important Victorian glasshouses in the world.