Extra care must be taken with amended soil medium to make sure your fertilizer feed is applied at rates that compliment the unknown NPK value in the soil. We recommend using certified facilities for soil testing to determine the best amendments, compatibility, and application rates.
Our feed charts work very well, but are only a guide. If you have existing cultivar/system specific feed charts, you can match your existing weekly EC targets while keeping the proportions in our feed charts. Another option is to start at half strength and gradually increase, while carefully observing the plants.