How to Water & Fertilize Bonsai
I once got asked how long do Sumo Cakes™ normally last? Mine have not broken down in 3 months.
The answer for me is 4-6 weeks. Even after recently getting 2.5′” of rain the cakes are still on top of the soil waiting to get wet again.
I recently read Dave Paris’s article in the American Bonsai Society’s August newsletter titled “Fertilizer – or How to Start a Holy War.” It got me thinking back to that question of how long Sumo Cakes last. I started to wonder if the person asking really knew how to use bonsai fertilizer cakes or for that matter basic bonsai watering technique. I am not saying that what this person is doing is wrong, it’s just not what I do. I covered some basics about fertilizers in this article, Bonsai Fertilizer Basics
Why do we fertilize or what is the purpose of fertilizing our bonsai?
We fertilize to provide the bonsai with the 3 Macro Nutrients (N=Nitrogen, P=Phosphorus, K=Potassium), the 3 Secondary Nutrients (Calcium, Magnesium, and Sulfur) along with any number of the all important Micro Nutrients. These nutrients promote cellular division within the bonsai, along with optimum health to fight off and withstand attacks from pests and diseases.
Fertilizer plays a bigger role than just to promote growth and health. Fertilizing our bonsai in the fall allows our trees to withstand the freezing cold temperatures of winter. Fall fertilization also gives our bonsai the chance to store energy in its buds, roots and vascular system to allow for the tree to come out of dormancy in the spring healthy and strong. Once the temperatures get warm enough the trees come out of winter dormancy in the spring. This stored energy is pushed into opening new buds and producing new leaves and needles. It’s important to fertilize in the fall for this reason. We want our bonsai strong and ready for this push. I wouldn’t expect you to run a marathon on an empty stomach, so why would we expect that from our trees.
We continue to fertilize in the spring to replenish the lost energy that was pushed to produce the new growth and to continue the overall health of the bonsai throughout the season and into the next. I also like to think that fertilizing in the late spring acts similar to fall fertilizing.
When temperatures get too high in the summer our trees go into a “summer dormancy” period until the temperatures cool again in late summer early fall. By fertilizing prior to this “dormancy” period, we are providing our bonsai with the chance to store the energy it needs so when it comes out of this “dormancy” it is able to continue its growth cycle.
What do I use, inorganic or organic fertilizers?
This comes down to personal preference. Both forms of fertilizer provide our bonsai with a means of receiving the nutrients they need, but both types of fertilizer go about it in different ways. I prefer Sumo Cakes.
Inorganic fertilizers are man made or chemical based and usually come in a liquid form such as Miracle-Gro, Bayer, and some other brands. You can also find inorganic fertilizers such as Osmocote in pellet form and others in powder. These fertilizers are usually mixed with water and are applied once every 7-14 days. Inorganic fertilizers give an initial quick dosage of nutrients. A quick hit. These nutrients collect in the pores of our bonsai soil and then washed away in the next couple watering. This leaves our bonsai without a steady source of nutrients. The harsh chemicals in this form of fertilizer can prevent the growth of Mycorrhizae. You can read more on Mycorrhizae in this article. Mycorrhizae, the Beneficial Symbiotic Relationship
Organic fertilizers are formed from plants and animals or are nature based ingredients. You will usually find these in the form of cakes, pellets, balls or other shapes. You can find organic fertilizers in liquid and powder form as well. (Fish emulsion, Kelp, Bone meal among others) Organic fertilizers are usually placed on top of the soil and are designed to break down over time (4-6 weeks). Every time you water or it rains, the bonsai is given a small dosage of nutrients. Organic fertilizers promote the growth of Mycorrhizae.