Regular trees are able to use their roots to look for nutrients. Bonsai trees, on the other hand, are planted in small, shallow containers and need to be fertilized in order to receive enough nutrients. Without fertilizer, it is not likely that your tree will thrive the way it’s supposed to. Knowing about fertilizer and how to apply it will ensure that you are able to help your bonsai thrive.

Parts Of Bonsai Fertilizer

Bonsai fertilizers must always have Nitrogen (N), Phosphorus (P), and Potassium (K). Each element serves a different, but very important purpose. Nitrogen promotes growth of the plant’s stems and leaves, Phosphorus helps your tree’s roots to grow healthy as well as the growth of flowers and fruits. Potassium encourages the growth of your plant in its entirety. Your bonsai fertilizer may also include other elements like Boron, Zinc, Iron, Copper, Manganese, and Molybdenum. 

When To Apply Bonsai Fertilizer

For outdoor bonsai trees, fertilizer should be applied throughout the length of the growth season, which is from early spring until the middle of autumn. Indoor bonsai trees should be fertilized consistently all year long since they do not have growth periods. Older trees generally do not need to be fertilized as frequently. 

Bonsai Fertilizer Ratios 

Applying the right kind of fertilizer is crucial for the health of your bonsai. Indoor and outdoor bonsai trees have different fertilizer needs, and outdoor bonsai have different needs depending on the season.

Indoor bonsai, which are tropical and subtropical trees, need balanced fertilizer throughout the year in whatever increments the packaging directs. These trees do not stop growing and are not exposed to the seasons like outdoor bonsai are, and therefore do not need fertilizer with different NPK ratios every season. 

For outdoor bonsai trees, it is often recommended that you use fertilizers with different NPK ratios depending on the season. In the spring, use a fertilizer with a high Nitrogen content with a NPK ratio of about 10:6:6. Use a balanced fertilizer in the summer, with a NPK ratio of about 6:6:6. And finally, use a low nitrogen fertilizer in the autumn, a NPK ratio of about 3:6:6. While this is a common way to fertilize your bonsai, many experts now suggest using a balanced fertilizer throughout the growth season, decreasing the amount of fertilizer at the end of the season.

If you wish to encourage your bonsai to flower, try using a fertilizer with a high Phosphorus content with a NPK ratio of 6:10:6. Older bonsai trees prefer a fertilizer with a low Nitrogen content

How To Fertilize My Bonsai 

Your bonsai fertilizer should have directions on the packaging for the amount of fertilizer you should use and how often you apply it. To balance your tree’s growth rather than stimulate it, you can reduce the quality recommended slightly. Solid fertilizer is recommended for outdoor bonsai. For a step by step guide for solid fertilizer, continue reading. 

  1. Get the tree you want to fertilize in front of you.
  2. Grab the solid fertilizer that you want to use.
  3. Put the amount of fertilizer that the packaging recommends into a small basket or cup. This is to prevent birds from eating the fertilizer and to keep them from being washed away when being watered.
  4. Place the cups into the soil.

For a step by step guide for liquid fertilizer, keep reading. Liquid fertilizer is recommended for indoor bonsai. 

  1. Get the tree you want to fertilize in front of you.
  2. Grab the liquid fertilizer that you want to use.
  3. Pour the recommended amount of fertilizer into a watering can with some water in it.
  4. When it is time to water your tree, water with the fertilizer filled watering can. 
bonsai fertilizer

Whether you have an indoor bonsai tree or an outdoor bonsai tree, fertilizing is a big part of the bonsai growing process. How much fertilizer to apply and when varies depending on what kind of tree you have and what season it is. You can choose to use a balanced fertilizer for outdoor bonsai trees or to change the ratios for different seasons, but you should always use balanced fertilizer for indoor bonsai trees. So long as you follow the directions on the packaging, your bonsai should grow healthy!