I'd go with the dolomite if your growing in soil. When you go to buy it, make sure you're not getting hydrated lime... that stuff can be overpowering and easy to add too much. (Had to find that out the hard way... ) I don't know how you'd go about diluting it, I always added it to the soil. Maybe someone else can chime in with a recommendation, or you could probably just do a search for "Lime, pH" and get plenty of good info. Also, don't spike the pH too much all at once, but raise it gradually instead. I know sudden pH fluctuations can actually shock the plant.