Salvia. Although it's not really a psychedelic in the classic sense. But the afterglow is very peaceful and can be somewhat drowsy.
But it depends what you mean by sedating. If you mean sleepy, then none of serotonergic psychedelics do this. If you mean evoking a sense of calm and peace, then many of them can do it. I have nodded off during the plateau of a DOC trip, and I have slept through a 69mg 2C-C trip before it even started, but I wouldn't call either of them "sedating".
aMT may perhaps be the most peaceful zen-like serotonergic psychedelic. But not sleepy by any stretch.
Ketamine actually keeps me awake, which is noticed if taken before bedtime.
Cannabis I wouldn't classify as a "psychedelic", but just a delirious mushy headfuck. Quite stimulating actually.
5-MeO trytamines are stimulating to the max.
4-HO/AcO tryptamines are stimulating, but in the case of psilocin it can make you lethargic and yawn. But that doesn't mean you are sedated - far from it in fact.
All 2C-x I've tried are stimulating.
LSA can be dreamy and calm, but I would hesitate to use the word "sedating".