Fertilizing Bonsai: Step By Step Guide For Beginners

Fertilizing Bonsai: Overview

Bonsai isn’t just about growing the perfectly scaled miniature tree. It is a mindful and intentional, almost meditative practise that allows you to focus on various techniques that embrace the science of art, sculpture and horticulture.

Already, as a bonsai enthusiast, you appreciate the beauty of nature.

With various tools and methods, you can create a faultlessly sculptured miniature tree. Patience and the health of the tree are paramount to you creating the ultimate specimen, but by not having a fully nourished tree can result in disease and, ultimately, death.

You will need to take care of your bonsai and devote time to ensuring its optimal care by evaluating its growing environment and adjusting the light, water and temperature when necessary.

In nature, roots automatically search for moisture and nutrients to keep themselves healthy. Because you have confined your bonsai to a small pot that naturally inhibits its root’s growth, you will have to give it a helping hand to keep it healthy.

The nutrients are necessary to turn water and carbon dioxide into food for your bonsai.

It’s important to use the finest quality fertilizer to feed the soil the best nutrients as they diminish.

The fertilizer provides your bonsai with the necessary nutrients such as nitrogen, phosphorus, and potassium. It allows your tree to grow strong and produce sugars to protect it against freezing during the winter months.

The Importance Of Fertilizing Your Bonsai

It would help if you supplemented your bonsai trees with valuable nutrients to compensate for the lack of soil. ‘Wild’ trees have a dense and complex root system, and they get nutrients from deep in the soil. Because bonsai trees are pot restricted, they don’t receive enough nutrients and oxygen to keep them healthy.

Balanced fertilizers contain the three most important elements required for plant growth and nutrition.

The elements are nitrogen (N), phosphorous (P) and potassium (K).

All quality fertilizer products are marked with an NPK value. The numbers represent the value of the macro-nutrients; the higher the number, the more concentrated the nutrient.

If the numbers are listed as 10-10-10, the rating shows that the fertilizer contains equal parts of nitrogen to phosphorus to potassium. If the rating is 20-10-10, the fertiliser contains twice as much nitrogen as phosphorus and potassium. 20-20-20 fertilizer has twice as much concentration of all three nutrients than 10-10-10.

If the rating is 20-5-5, it has four times more nitrogen than phosphorus and potassium.

Each of these elements feeds the plant in its own way.

Each plant will need a different amount depending on the type of tree, the soil you’ve used, the time of year, and its overall health.

As a rule of thumb, indoor plants need to be fertilized throughout the year, whereas those grown outside will only need feeding during the growing season.

It is crucial to choose the right fertiliser or fertilizers to give your bonsai the correct nutrition throughout the year. NPK 10-6-6 is an excellent mix for early spring food to awaken your bonsai from its dormant winter nap and give it a great start at the beginning of the growing season.

A more balanced fertilizer such as 6-6-6 is best for the summertime.

To prepare your bonsai for the winter season, begin to slow its growth period down by giving it a low nitrogen feed 3-6-6.

The Three Key Fertilizer Elements

The Importance Of NPK

No one said this was easy. Not all plants have the exact nutrient requirements. Sometimes, you can do more harm than good without care when applying additional chemicals without thoroughly understanding their roles.

For example, if you feed your bonsai with a fertilizer that has high levels of nitrogen, you will force the plant to send all of its energy into growing foliage instead of flowers or roots.

If you are uncertain how healthy and vital your soil is for your bonsai, you can use a slow-release fertilizer which is less likely to challenge the plant’s physical condition. You can also have the soil tested.

Nitrogen, Potassium, Phosporus

Nitrogen helps the bonsai continue to steadily grow its trunk, branches, stems and produce healthy leaves. Nitrogen aids with Chlorophyll production, the green pigment found in healthy plants. If the leaves start to yellow, this often indicates that the plant has nitrogen deficiency.

Nitrogen is the essential nutrient for the growth of strong leaves and shoots.

Phosphorous provides nourishment to provide strong roots and strengthens the plant to make it amenable to training and styling. It’s an essential nutrient for your tree in the spring to promote overall healthy growth.

Phosphorous is vital for a wide range of plant processes, including photosynthesis, respiration and flower production.

Potassium gives the plant the necessary nutrients to produce a slew of fruit and flowers. Potassium is also used in photosynthesis and improves winter hardiness.

Phosphorous and potassium have some overlapping roles in the growth of healthy root systems.

When To Fertilize Your Bonsai

When Should I Apply Fertilizer?

You should fertilize most bonsai trees between early spring and through the growing season to mid-autumn. Older trees tend to need less attention and fertilization, depending on their stage of development, health and age.

You can fertilize indoor bonsai trees throughout the year. Because the bonsais have intentionally less soil, they receive fewer nutrients than other house and ornamental plants. Your tree should be fed weekly with liquid bonsai fertilizer and monthly with slow-release organic fertiliser throughout the growing season.

Towards the end of late summer or early autumn, your bonsai will start to prepare for its dormancy period; you can reduce your fertilising schedule to once a month.

Each class of bonsai requires particular attention:

Deciduous Bonsai Trees

You should fertilize deciduous bonsai such as apple tree, brush cherry, Chinese elm, firethorn, Japanese maple and ficus bonsai each week throughout the growing season.

During the winter, give your tree NPK 0-10-0 fertiliser every month.

As soon as the leaves have fallen, you should stop feeding the tree.

Conifer Bonsai Trees

You should fertilize deciduous bonsai such as apple tree, brush cherry, Chinese elm, firethorn, Japanese maple and ficus bonsai each week throughout the growing season.

During the winter, give your tree NPK 0-10-0 fertiliser every month.

As soon as the leaves have fallen, you should stop feeding the tree.

Tropical And Sub-tropical Trees

Tropical and sub-tropical trees are hungry throughout the year. The Brazilian rain tree, bougainvillaea, ficus and Fukien tea tree should be fed at least once a week during the growing season and fed monthly between the autumn and spring. You can continue to use the same fertiliser throughout the year.

You should only feed healthy trees and never starve your bonsai. Regular fertilization will keep your tree healthy and prevent it from developing spindly, out of shape limbs.

If, for any reason, your tree is sick, let it recuperate before you start feeding it again.

Be Careful: DO NOT Overfertilize Your Bonsai

Your bonsai is quick to tell you if it is not feeling well. There are various ways of knowing if you have over-fertilized the tree. There may be a crystalline deposit of fertiliser on the very top of the soil; the leaves might start to yellow and turn brown on their tips. Slowed growth, wilting branches or leaf loss could also be a sign.

Be particularly careful with newly repotted bonsai plants. Take care not to fertilise them for a month after repotting.

Which Fertilizer To Use: My Top 3 Choices

Liquid Vs Solid – Which Works Best?

Slow-release organic fertilizers are pellets, and as you water the tree, the bacteria and fungal activity break down the pellets, and the soil absorbs the nutrients.

The fertilizer is not particularly strong, with an NPK of 3-3-3. Regular application ensures that your tree always has nutrients available. A liquid chemical feed can be as strong as 20-20-20 and is rapidly diluted and dispersed during rain and watering.

Organic fertilisers add microbes into inorganic soils and help create and maintain a healthier ecosystem for your bonsai.

Interestingly, plants do not absorb nitrogen unless the ambient temperature is constantly above 12 degrees Celsius and will only be absorbed when the tree is ready.

Westland 20100354 Bonsai Tree Feed Concentrate, 200ml

The Westland bonsai tree feed concentrate is an easy-to-use plant food with an NPK of 6-4-7. It is enriched with essential nutrients and trace elements that will enable your bonsai to thrive throughout the year.

The nutrients will encourage strong roots and healthy green leaves.

The manufacturer recommends feeding your bonsai every second watering during the growing season in the spring and summer. Every fourth watering in the dormancy season throughout the autumn and winter months is ample.

There is an easy-use measure so that you can use the exact dosage required.

Westland recommends keeping your bonsai out of intense sources of heat and any draughts.

Spray your tree with tepid water twice a week to maintain humidity levels and gently sponge the leaves occasionally to remove any dust particles.

They also suggest nipping branches back as soon as they begin to grow to avoid the noticeable appearance of pruning cuts and possible scarring.

Bonsai Focus Liquid Concentrated Fertilizer, 300ml

Growth Technology has been developing innovative horticultural products for almost 40-years.

They are leaders at creating specialist plant solutions for bonsai enthusiasts.

They have formulated Growth Technology Bonsai Focus concentrated fertilizer for bonsai trees with very little soil to flourish.

They understand that it is essential to maintain the vital health and fertility of the soil for the long term success of the plant.

Not only does the liquid formula have a balanced NPK of 1.9-0.7-3.9 (in water), but it is also enriched with humic and fulvic acids and seaweed to maintain ultimate fertility in the soil.

The manufacturer recommends using this during each watering throughout the growing months between March and August and sparingly through the winter.

BioGold 900g Original Slow Release Bonsai Fertilizer

Biogold is a slow-release organic bonsai fertilizer that is easy to dose, odourless and economical. Professor Yamaguchi from Ibaragi University in Japan developed the specialist fertilizer. It is manufactured by Kyuka-En Bonsai Nursery and used across the world on all species of bonsai trees.

The balanced NPK is 5.5-6.5-3.5. Not only can the slow-release fertilizer be used on bonsai trees, it can be used on home, balcony and garden plants. The organic product has an even release of nutrients, and there is no risk of over-fertilization or salinisation.

BioGold recommends that you fertilize your bonsai every six weeks between March and September. It is suitable for deciduous trees, coniferous bonsai trees, azaleas, and other indoor plants.

It is even suitable for specialist bonsai trees like Akadama, Kanuma and Kiryua. The manufacturer has shaped the pellets to prevent roll-off.

Fertilizing 101: Your Top Questions Answered

Do I Need To Water In Liquid Fetilizer?

First of all, liquid fertilizer comes as a concentrate. You need to dilute it before you add it to the soil around your bonsai tree or any other plant, for that matter. The good thing about liquid fertilizers is that they are fast-acting and quickly absorbed into the soil. It is important to ensure that you properly water in the fertilizer to ensure it reaches all parts of the root system.

Every time that you water your bonsai, you wash away the fertilizer that you previously added. It’s essential to apply the liquid formula frequently. Granular fertilisers are applied dry, and they must be watered in.

The application of water triggers an even release of nutrients.

Both types of fertilizers are ideal for bonsai trees, and specialists will tend to use the two types of fertilizer for the best balance and ultimate health.

How Do You Apply Liquid Fertilizer To Bonsai?

It’s important that you lightly water the soil before adding the diluted liquid fertilizer to prevent pooling on the top of any dry soil. The fertilized water should run evenly through the soil to nourish the entire root. Next, using a sprinkler, water the entire plant, including the leaves, with the fertilized water.

Be careful to stop watering before the fertilizer runs out of the holes.

Finally, with freshwater, sprinkle the entire plant to wash off any excess fertilizer from the leaves and pot.

Liquid fertilizer should be applied at least once a week during the growing season and substantially reduced to between three and six weeks during the winter dormancy period.

How Often Should You Feed Your Bonsai Tree?

There is so much information available about how to fertilize your bonsai tree correctly.

You can generally split bonsai into two categories.

  • Trees in development need to be fed throughout the growing season.
  • Trees undergoing training need to be fed when the spring growth has hardened off and continued to the end of the growing season.

A consistent approach is the best way to ensure success. Create an annual schedule and put it on your calendar. Be resourceful with your fertilising habits. If the instructions state that you should apply fertilizer bi-weekly, but you know that your bonsai will benefit from weekly applications, simply dilute the fertilizer further and feed every week.

Consider using a combination of liquid and granular fertilizer so that your bonsai will receive nutrients every time you water. It is worth noting your various approaches to fertilisation, organic, inorganic, liquid or granular methods.

Over time, you can analyse what the best fertilizing plan for your bonsai is.

Be careful not to over-fertilize if your tree looks sick or weak.

Many bonsai enthusiasts think that adding additional nutrients and chemicals will save it. The opposite, in fact, is true. Too many nutrients may prevent the tree from healing naturally and overpower it completely.

How Do You Make Bonsai Fertilizer?

Bonsai trees need to be kept vital and healthy and need you to give them the nutrients they require. The trees need a balanced mix of nitrogen, phosphorous and potassium, and micronutrients such as iron, magnesium and zinc.

As the root system is so tiny, there is always a risk of damage from over-fertilization. Slow-release fertilizers release nutrients each time the tree is watered.

Various home recipes include a mix of organic materials, including seed meal, fish products and kelp to produce micronutrients.

Two Popular Recipes For Pellet-Sized Fertilzser Balls

Sunset Bonsai Club

Combine the following ingredients and adjust the amount of liquid so that you can form small balls in your hand.

  • 9 cups of cottonseed meal
  • 4 cups of bonemeal
  • 2 cups of fish meal
  • 3/4 cup of kelp meal
  • 4 cups of fish emulsion
  • 1 cup of liquid fertilizer

Columbus Bonsai Society

Combine and use enough liquefied kelp or other liquid fertilizer to create a paste that you can form into small balls.

  • 4 parts cottonseed meal
  • 2 parts blood meal
  • 1 part bonemeal

Funnily, fertilizer balls have earned themselves the nickname poo poo balls. The fish and blood meal ingredients are primarily responsible for the smell. Ensure that you wear protective gloves and make them outside.

The balls can attract flies and animals, so they should be dried and stored in a suitable place.

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