Bonsai Tree Fertilizer

Care of bonsai includes bonsai tree fertilizer. It supplies plants with the essential nutrients necessary for their growth while in a container.

Bonsai are living, containerized plants and they need feeding to stay healthy.  This can be done with tablets, pills, powders, granules etc.  There are both synthetic and organic types. One of the most popular is water soluble.  Some growers create their own fertilizer cakes.

A common bonsai myth is to use fertilizer half strength, because it is a little tree.  Not true ... and do not give your bonsai extra fertilizer either.

Unless you have more specific instructions for your tree, use an even numbered, common house plant formula such as 20-20-20 or 14-14-14, and follow the instructions on the container.  These numbers are more important than the brand name.

Most brands have several different formulas. When someone tells you to use 'X' brand, that is not enough information.

(Soil should be moist before using liquid products).

ANOTHER MYTH:  Just as there is no one plant called bonsai, there is no one type of "bonsai tree fertilizer".

See more bonsai myths.

Time Release for
Bonsai Tree Fertilizer

Kingsville Boxwood Bonsai
Rodney Clemons

Because container plants are watered frequently and soluble fertilizers leach quickly, many growers use slow-release (often called time-release) pellets or prills.

These can be mixed in the growing medium to prevent them from bouncing off the top of the soil during rain or watering.

Another good reason for mixing these “little balls” in the soil is, a crust often forms as they dissolve if placed on top. This crust can disturb the effectiveness of your watering.

If you choose to sprinkle this type of fertilizer on top of the potting medium, be sure to disturb the top of the soil mix from time to time with a chop stick.

What Do the Numbers Mean?

Fertilizers have three numbers printed on the package. These numbers refer to the three nutrients that plants need in the greatest quantity.

These elements are part of the macro-nutrients -- nitrogen (N), phosphorus (P) and potassium (K). Numbers such as 20-20-20 or 7- 9-5 indicate the total percentages of N-P-K (in that order).

  • Nitrogen (the first number) N is important for the vegetative growth of plants. Leaf yellowing is often a sign of lack of nitrogen. Too much nitrogen can slow down the manufacture of fruit and flowers.

  • Phosphorus (second number) P is critical for roots, fruit and flowers. A blooming plant usually responds to extra phosphorus by displaying more flowers.
  • Potassium (third number) K makes the structure of the plant strong. This increases resistance to stress and disease. (Potassium is also known as potash.)

Pennington Seed company has a very detailed

explanation of labels.

Changing the fertilizer formula you use, can make an amazing difference in the response of your bonsai!

Other minerals are also provided in fertilizer. They are important; however they are available in much smaller amounts and are a mixture of the other macronutrients and micronutrients.

Whichever type of fertilizer you use, "feeding" is an important part of bonsai care. If you suspect your tree is sick, fertilizer may not fix it.  Look for the cause of the problem, first

See the Plant Pests and Bonsai page.

Once your bonsai is "finished," it enters a maintenance period.  The numbers on your bonsai fertilizer should be more even and lower overall. 

A special thanks to Jeff Wasielewski at Fairchild Tropical Botanic Garden for reviewing the  fertilizer information on this page.  

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