Northeast of town (1.5km) is the 88-hectare botanic garden, also a wildlife and bird sanctuary, plus recreational and ceremonial space. Pathways head through wetlands and magnificent areas of cacti and native plants. A canyon has an eponymous freshwater spring, the Charco del Ingenio. Don't miss the Conservatory of Mexican Plants, which houses a wonderful array of cacti and succulent species. Two-hour tours (in English) depart every Tuesday and Thursday at 10am (M$80). Monthly full-moon ceremonies also take place here.
Each Tuesday, Thursday, Saturday and Sunday a complimentary bus service leaves Calles Mesones in front of Plaza Cívica at 9:30am, returning at 1pm. Otherwise, getting to the garden can seem a slightly prickly business, thanks to urban development on the town's outskirts, which blocks the original route, but it's worth persevering. Walk uphill from Mercado El Nigromante along Homobono and Cuesta de San José. Fork left up Montitlan past a housing development (known as Los Balcones). Continue for another 15 minutes to the main gate. Be sure to keep the garden boundary fence on your left as much as possible. (Occasionally you may have to head around the new houses on sidewalks, after which you head back to the fence.)
Alternatively, a 2km vehicle track leads north from the Soriana shopping center, 2.5km southeast of the center on the Querétaro road. This can be reached on 'Soriana' buses from the bus stop from Mesones, near Plaza Cívica (10mins, M$5). A taxi to the gardens from the center costs from around M$50 to M$60.