Expert: Wayne King - 5/27/2009

Question
Hi King,
It is said that there is harmful effect in environment if using chemical fertilizer for the long time. So can I soak fresh cutting grass in the water for about a week, and using this water as liquid fertilizer to feed cymbidium and pitaya(jungle cactus, dragon fruit)? And how to feed so that does not hurmful to the plants.
Thank you.

Answer
Quy, I appreciate your concern for the environment. Most environmental harm comes from widespread use over large areas such as pastures, lawns, etc..  Using small quantities on pot plants should have minimal impact.  Soaking cutting grass to create "natural" fertilizer can be problematic from several perspectives.  First, an organic brew can be a perfect environment for the growth of bacteria and fungi. Most organic fertilizers such as seaweed extract or fish emulsion that can be found on the shelves of garden centers are heat treated to eliminate micro-organisms and render the fertilizer sterile. Second, the "fertilizer" component, which consists primarily of urea, cannot be used by plants until it undergoes "digestion" by micro-organisms to break it down to the nutrients needed for plant growth.  Many plant foods found on shelves, in fact, contain urea as a source of nitrogen.  It takes months for urea to break down before it is available as salts for use by the plant. I recommend using low concentrations of plant foods providing nitrogen and phosphorous via inorganic salts that can be immediately available for use by the plant.  Read the label on the plant food container to identify the source of nitrogen.