Spring is the obvious answer. Late March through April, when the Haspengouw orchards are in blossom, is the most spectacular time to visit. The landscape around Sint-Truiden transforms completely, and the town capitalises on it with guided blossom routes and cycling events. The precise peak varies by year and variety — cherry trees bloom earlier than apples and pears — so check with the tourist office for current conditions.
Summer is pleasant, and in even-numbered years the Kriekenfestival (cherry festival) fills the Grote Markt in late June or early July — a genuine local event rather than a tourist confection. Autumn brings harvest, and fruit stands around the region fill with fresh produce.
Winter is quiet but the indoor attractions — the abbey treasury, the cultural centre at Kasteel Nieuwenhoven — remain open and are more appealing on a cold day than an empty market square.