Instructions can be downloaded at the bottom of this page.
Soft Rock Phosphate that is dug up out of the ground, there is a limited supply.
Some leaves will start to turn red, others will be darker green than normal and will start to drop off of some plants.
Phosphorus deficiency is most often manifested as purple coloring of the leaves, particularly the leaf veins.
In severe cases the whole plant may take on a purple hue.