Yes higher PH's can slow growth a bit. 7.2 is not too bad though. 6.0 - 6.5 with your pro-mix would be better.

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Herbus Reviewed by Herbus on . Please help! (Spraying/Watering) My plants need you! I was just looking at some of the post about healthy plants size and Iā??m a little concern with my plants. My 3 weeks old plants are healthy with a very nice green color but they donā??t seem to be growing enough. (They donā??t have lotā??s of leaves and tend to stay quite small) They are under a full spectrum fluorescent (24/0) at about 1 to 2 inch from the top. I started them from seeds. Iā??m using the Ultimate Potting Mix from Pro Mix. POSSIBLE PROBLEM: Rating: 5