Had vaginal hysterectomy with anterior/posterior repair, 5 weeks ago. Is it safe to vacuum rugs and do mild gardening and gentle yoga exercises?

Probably. Probably. But check with your doctor.
Gradually. You can generally increase your activity after 4 weeks. If it doesn't hurt it is probably ok. If you feel pulling, tugging, pain, or pressure in the pelvis you are doing too much and should ease up.