A soil that has composted HUMUS as its major component instead of peat will have a naturally more stable pH, buffering at 6.8-6.9 due to the content of organic acids that your plants will really love.
I see you are in Canada and I don't know what the farm supplies sell there, but you might try calling a couple and asking for a 'humus-based potting mix or soil amendment'. Then add perlite and you have a decent medium. Bonus, it's usually WAY cheap.