Yeah, using dolomitic lime (garden lime) saved me from a lot of headaches with premixed potted soil. The longer you use the soil the more acidic it gets, especially with heavy feeding. I used to have all kinds of problems with yellowing and burned looking leaves. It got REALLY nasty when I used prefertilized potting soil and added additional ferts, difficult to track the problem down at first.

Two tbls of garden lime per gallon of soil will be the most important additive you can bless your plants with, IMO.