Dried Kelp (for K and P). It helps plants develop stronger roots. The mixing powder is more cost effective than the prepared liquid form.
It has mostly K and it complies with the guidelines for K for SIP fertilizers. For example, a fertilizer for EarthBox SIP should be labeled between 5 and 15 for all 3 numbers (N-P-K).
Here is a buying option from Amazon (Maxicrop seaweed):
In Chicago, the local retailer Brew and Grow has some of the best prices for dried kelp: Algamin Kelp Meal - Soil Amendments - Growing Medium http://bit.ly/QtjvNA
“Up, Down and All-Around” is another way to think about NPK and the numbering system for fertilizers. Your lawn needs nitrogen for the leaves’ color and growth, phosphorous for strong roots, and potassium for overall health. Source: Home Depot.
Brew & Grow - Irving Park - Chicago, IL http://bit.ly/Qtjvx2