Should I Adjust pH When Growing Pot Outdoors?

Dear Dan,
If you were doing an outdoor grow, would you still pH balance your nutrients to 6.5? Isn’t rainwater at around a pH balance of 8? If you use a plastic 55-gallon drum with drippers could you put a funnel on the top of it to collect rainwater? And if you added your nutes to this 55-gallon drum what would you do about the pH balance? Thanks! — Climbing Higher

Dear CH,
The first thing you should do is test the pH of the existing soil in your outdoor grow. A simple kit will give you a good idea of what you’re working with, and you can act accordingly. Lime can raise it, while elemental sulfur will bring it down. If you’re water tends to run lower than 5.8 or higher than 7, I would certainly adjust pH before adding your nutrient solution to your plants.

The pH of rainwater fluctuates, but most rainwater in the U.S. tends to be substantially lower than 8. Average pH of rainwater tends to run in the 5’s and 6’s. As CO2 levels in the atmosphere continue to rise, we can expect the pH of rainwater to become even more acidic, thus more acid rain. If you’re collecting rainwater in a 55-gallon drum, add your nutrients, then adjust the pH (using pH up or down) to optimal levels before watering your plants.