NPK
Up-Down-All Around
by Paulette Mouchet

Originally published in "The Rose Garden" newsletter, May 2004. Updated February 2007.

Nitrogen (Up)

A key ingredient of protein molecules and a part of the chlorophyll molecule. Adequate nitrogen is associated with vigorous plant growth (up above the soil) and dark green color.

Phosphorous (Down)

It has many vital functions, especially in energy transfer processes and is always found in abundance in root tips and stem tips (down below the soil), which are growing rapidly. High levels of phosphorous are important for good root development and seed growth, newly planted shrubs, trees, bulbs, etc, and help to increase the size and number of flowers.

Potash/Potassium (All Around)

Is absorbed by plants in larger amounts than all other element except nitrogen. Potassium levels affect the rate of photosynthesis and is associated with fruit formation, winter hardiness, and disease resistance (all around). Also, adequate potassium is necessary for water intake by the plant cells: it opens the stomata so cells can absorb nutrients.