The first thing to do is to check the pH, which is the measure of alkalinity or acidity of a substance. It is measured on a scale of zero, the most acidic, to 14, the most alkaline. Seven is neutral. Nutrients are most available in a slightly acid solution, from six to about 6.5, and this is the best pH range in which to grow plants.
Not only should the water pH be measured and adjusted after adding fertilizer, but the pH of the soil or planting medium should also be measured. If the soil or planting medium is highly acidic, the irrigation water should be adjusted to a less acidic level. Highly alkaline mediums such as rockwool and some western soils should receive more acidic water?nutrient solutions.
Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA. You can also email Ed at [email protected], and send queries via his websites at www.ask-ed.net. All featured questions will be rewarded with a copy of Ed’s new book, Best of Ask Ed: Your Marijuana Questions Answered. Sorry, Ed cannot send personal replies to your questions.