Oh you can add it every week or every other week (along with your fertilizers) If it looks a bit burned you can do a flush, 3 tablespoons is a bit much, I would stick with one for now. You might want to wait two weeks before reapplying, just to make sure your plants have time to take up the molasses. But it sounds like you should be fine for now.

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Let me slip out of consciousness and into something a little more comfortable...