Waqanki is the easiest place near Moyobamba to understand the "City of Orchids" nickname. The garden gathers orchids, bromeliads, heliconias, and other humid-forest plants, with hummingbirds often working the flowers and feeders nearby.
It is small enough for a relaxed visit but rich enough to reward slow looking. Go in the morning if birds matter to you, and combine it with San Mateo hot springs on the same road.