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.

A dry napkin with food coloring applied
A wet napkin with food coloring applied

How do I water my bonsai?
In the opening about the person who asked me about how long the cakes last, I mentioned maybe the person didn’t know basic bonsai watering technique. To that, I say that maybe I don’t know basic bonsai watering. I water all of my trees once a day. I have a bench that gets morning sun and afternoon shade and one bench that gets full sun all day long. When I water my bonsai I make sure that I soak the soil of the bonsai so water is running out of the bottom of the pot. Not just a little water. I soak my soil with lots of water. if you are using the right kind of soil, there is no way to over water your bonsai this way. I then make a second pass over the same trees on that one bench making sure to soak my trees soil, again with water running out of the bottom. I then move to the second bench and do the same thing.

Why make two passes?
I make two passes for a few different reasons. One reason is to flush the soil of dust and to draw fresh air into the root zone. A second reason would be too cool the roots and pot. Another reason is to soften my organic fertilizer cakes or to reactivate my inorganic fertilizer salts. Finally, a different reason would be to make sure I am getting the whole root zone wet. When I make my first pass with my hose I think of it as “priming my soil”. I am “pre-wetting” the soil. For me, the second pass is really when the watering and fertilization happens because my soil is ready to receive the water and my fertilizer is softened and ready to break up.

When using inorganic fertilizers, the first pass wets the soil and the salts of the fertilizer, reactivating the fertilizer and “priming” the soil. If I was applying liquid inorganic fertilizer I would do this during the second pass because the soil is ready. I imagine it like adding a drop of food coloring to a paper towel. The first pass primes the soil getting it wet, while the second pass allows the soil to receive the fertilizer and distribute it better, like adding food coloring to a wet paper towel.

Take a dry paper towel and drop one drop of food coloring on to it. Then follow that up by doing the same thing on a wet paper towel. The food coloring should disperse more on the wet paper towel.
That same effect is why we “prime” the soil with the first watering.

My preferred method is using organic fertilizers. I obviously recommend Sumo Cakes. When we use organic fertilizers and we make the first pass with our water hose, we are “priming” the soil. With this first pass, we are also loosening up the particles of fertilizer that already reside in the soil along with softening the organic fertilizer cakes that sit on top of the soil. If you use tea bags for your fertilizer you are also getting the tea bags ready. I like to think of this first pass as taking a hot cup of water and placing a tea bag into the water. Nothing much really happens.

On the second watering, again is when I feel everything happens. The fertilizer cakes on top of the soil visibly start to break up as pieces fall off of the cake and get washed into the soil. The tea bags have had a chance to steep. The second pass of water over the tea bags in my mind is as if you were to move the tea bag around in your cup of hot water. The tea releases the nutrients into the soil.

 

Why I like Organic over Inorganic Fertilizers

The reason I like to use organic fertilizer cakes vs. inorganics is that of the constant feeding the bonsai get with every watering. Liquid inorganics, who knows how much your bonsai is getting fertilized if it rains all day. Is all of the fertilizer washed out of the soil? Who knows. At least with the cakes, you can see how much of the cake is still there.

Organic fertilizers also help promote the growth of Mycorrhizae. Again, you can read more about that in this article (Mycorrhizae, the Beneficial Symbiotic Relationship). Organic fertilizer promotes a healthy root zone while inorganics in my mind, focus solely on top growth.

Most fertilizer products do not provide all of the nutrients that our bonsai need. You will end up buying multiple products to provide your bonsai with all of the nutrients they require. I am proud to say that Sumo Cakes makes feeding your bonsai easy, as these cakes have a guaranteed analysis of providing 9 micro nutrients along with all 3 secondary nutrients and the normal NPK. Also included in Sumo Cakes is a plethora of Mycorrhizae species to help promote a healthy root zone.

Remember to make two passes with your water hose. Your trees will love you more for it.

Sumo Cakes™ (Bonsai Fertilizer)

$12.00
4.95 out of 5
  • Quantity: 12 oz
  • NPK ratio 6-7-6
  • Multi Source Fertilizer
  • Packed Full of Micro Nutrients
  • Vast Selection of Soil Microorganisms to Help Create an Active Root Zone
  • Loaded with Naturally Occurring Vitamins & Minerals
  • For use with Bonsai, Flowers, Vegetables, Tress, Shrubs, and Houseplants.
  • Recommended for outdoor use but safe indoors

Medium Fertilizer Baskets

$4.00
5.00 out of 5
  • Pack of 10 Medium Fertilizer Basket with Spike.
  • Basket size is roughly 1 1/4″″ x 3/4″
  • Great for Shohin and larger bonsai.
  • Keeps your solid fertilizers on the surface.
  • Water directly onto the basket for quickest release of nutrients.

Sumo Cakes™: Buds & Blooms (Bonsai Fertilizer)

$12.00
5.00 out of 5
  • Quantity: 12 oz
  • NPK ratio 6-9-5
  • Multi Source Fertilizer
  • Packed Full of Micro Nutrients
  • Vast Selection of Soil Microorganisms to Help Create an Active Root Zone
  • Loaded with Naturally Occurring Vitamins & Minerals
  • For use with Bonsai, Flowers, Vegetables, Tress, Shrubs, and Houseplants.
  • Recommended for outdoor use but safe indoors
  • Recommended for outdoor use but safe indoors.

Sumo Cakes™: Acidic Blend (Bonsai Fertilizer)

$12.00
5.00 out of 5
  • Quantity: 55 cakes
  • NPK ratio 7-6-6 
  • Multi Source Fertilizer
  • Packed Full of Micro Nutrients
  • Vast Selection of Soil Microorganisms to Help Create an Active Root Zone
  • Loaded with Naturally Occurring Vitamins & Minerals
  • Great for Bonsai, Azaleas, Rhododendrons, Evergreens, and other Acid loving plants.
  • Recommended for outdoor use but safe indoors.

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