Witnesses said the blaze has gutted the main restaurant building and garden shop and burnt out the roof. Tayside Fire and Rescue said the fire started at around 2am.
Two pumps from Forfar, one from Kirriemuir and one from Kingsway East in Dundee attended.
Lochlands is a Camellia specialist, propagating and growing 50 varieties in its nursery. The site includes a caravan site, restaurant and equestrian centre.
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