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What Is The Best Fertilizer For Bonsai Trees? (For Each Season)

Getting and providing the right feed and fertilizer for your bonsai tree is essential. 

But many people who care for these meaningful trees are left wondering which fertilizers are the most suitable.  

The best fertilizer for a bonsai tree depends on the season, the setting (indoor/outdoor), and whether or not you want the tree to flower. 

Generally, though, you should use a fertilizer with high nitrogen content in its Nitrogen-Phosphorus-Potassium (NPK) ratio. 

Yet, some bonsais, like flowering species, may need different ratios, such as those with more phosphorous. 

Keep reading as I unpack the best NPK fertilizer ratios for different bonsai tree growing scenarios. 

I’ll also share a few recommendations for fertilizer products. 

Best Fertilizers for Outdoor Bonsai Trees

When looking for the correct type of fertilizer, you need to consider the season and weather if you’re growing the tree outside

While some growers choose to use a balanced ratio of nitrogen, phosphorus, and potassium throughout the seasons, it may be best to use a low-nitrogen ratio fertilizer when the weather gets colder. 

So, as the year progresses, you can start tapering off on the amount of nitrogen in your fertilizer blend. 

In fact, some growers even cut out nitrogen entirely during the winter season so that their bonsai trees don’t have to waste energy on growth when they’re dormant. 

Overall, though, you should follow these general fertilizer ratios (or a similar ratio) based on the season you’re experiencing:

  • Spring – NPK 10-6-6
  • Summer – NPK 6-6-6
  • Fall – NPK 3-6-6
  • Winter – NPK 0-10-10

Best Fertilizer Products for Outdoor Bonsai Trees

Below are some of my recommendations for the best outdoor bonsai tree fertilizers, from spring to winter blends. 

Spring – The Grow Co Bonsai Food Slow Release Pellets

This bonsai tree fertilizer is great for outdoor trees experiencing springtime weather. 

You can use this fertilizer on bonsai varieties, including ficus, juniper, Schefflera, jade, ginseng, money tree, bamboo, and other dwarf tree varieties.

Summer – The Grow Co Organic Liquid Bonsai Food 

For summer, I recommend a gentle and balanced fertilizer blend for outdoor bonsai trees. 

The Grow Co’s organic bonsai food has a balanced NPK of 1-1-1 that won’t burn or damage the tree roots. 

Fall – Dyna-Gro Liquid Bonsai Food 

For the fall season, as the weather cools, I recommend trying a blend with a lower nitrogen content, such as Dyna-Gro. 

It has a 7-9-5 NPK ratio that you can dilute to your desired concentration before using. 

Winter – New England Bonsai Gardens Fall; Winter Fertilizer 

I recommend a nitrogen-free fertilizer for outdoor bonsai trees in the winter months, such as this New England Bonsai Gardens Fall and Winter Fertilizer.

This feed has a 0-10-10 NPK ratio and supports root health. 

Plus, it protects bonsai trees against incoming winter weather. 

Best Fertilizers for Indoor Bonsai Trees

Indoor bonsai trees, on the other hand, won’t face the changing weather, so the season doesn’t matter as much when choosing a fertilizer. 

In most cases, your home will generally maintain the same temperature and humidity levels year-round, although access to natural light may change throughout the year.

Because of these conditions, you’ll want to find a liquid fertilizer with a more balanced ratio of NPK (6-6-6 or 1-1-1) for indoor trees.

And you won’t be changing that ratio too much overtime since indoor bonsai trees will grow all year round.

The main exception is if you’re facing specific issues, such as root damage or a lack of flowers, that require particular nutrient ratios to fix.

Overall, just remember that indoor bonsai fertilizer should definitely have some nitrogen content, but not so much that it overpowers the plant. 

You should also consider the type of bonsai plant that you have. 

It’s more common to grow tropical and sub-tropical bonsai varieties indoors, as they will thrive better in that environment, so you will probably need a fertilizer suited to these trees.

Best Fertilizer Products for Indoor Bonsai Trees

Below are some of my top picks for fertilizers to use on bonsai plants that grow indoors. 

I’ve picked out one liquid fertilizer as well as one pellet/granule fertilizer to give you options for different preferences. 

Uncle Bill’s Bonsai Brew 

I recommend this product because the manufacturer makes it specifically for indoor bonsai trees. 

It’s a balanced NPK (3-3-3) formula in a water-soluble liquid blend that is easy to apply to indoor bonsais.

Superfly Bonsai Slow Release Fertilizer Pellets

This bonsai fertilizer isn’t a liquid fertilizer, but it does have a pretty balanced blend of NPK (5-7-4). 

The nutrients release themselves over a 1-2 month period to support indoor bonsai tree growth, including root, leaf, and flower development.

Best Fertilizers for Flowering Bonsai Trees

If you want your bonsai tree to start flowering, you will need a unique nutrient ratio fertilizer. 

In this case, your fertilizer shouldn’t be as balanced, and instead, it should have a higher phosphorus content in the NPK ratio.

You need more phosphorous because it is the nutrient that supports the growth of fruits and flowers in most plants. 

You might try out a 6-10-6, 3-12-6, 7-9-5, or similar ratio fertilizer since phosphorous helps bonsai trees grow healthy roots and flowers. 

A lack of phosphorus for a bonsai tree may lead to stunted growth, at which point it will struggle to flower. 

Best Fertilizer Products for Flowering Bonsai Trees

I have a couple of recommendations for fertilizer products if you want to get your bonsai tree to start flowering.

Note, though, that you may still need to slightly alter the nutrient ratio of your fertilizer depending on the growing environment (indoor/outdoor or season).

Dyna-Gro Bloom

Dyna-Gro Bloom liquid plant fertilizer is an incredibly effective bonsai tree fertilizer when you want to promote flowering. 

It has an NPK ratio of 3-12-6 (fairly high in phosphorus) to promote more vibrant, healthy blooms. 

And because it’s a liquid fertilizer, you can dilute it as much as you want or need to before applying it. 

Dyna-Gro Liquid Grow

Dyna-Gro Liquid Grow is another valid option when you want to get your bonsais to start blooming.

It’s a less intense concentration of phosphorus content that still provides enough of the nutrient to support flowering.

It uses an NPK ratio of 7-9-5 so that your bonsai tree can still get sufficient nitrogen and potassium to support the roots and leaves.

Best Fertilizers for Beginner Bonsai Tree Growers

When it comes to newbie bonsai growers, picking out a fertilizer may seem difficult. 

But, it doesn’t have to be. 

Generally, when you’re just starting out, you should stick with a balanced NPK ratio (i.e., 6-6-6) since your main focus is keeping the bonsai tree healthy and alive at this point. 

Experts recommend moving on to varying NPK fertilizer ratios once you’ve nurtured the tree with a balanced blend.

Dyna-Gro blends are always a pretty fail-proof fertilizer option if you want to try your hand at bonsai tree care. 

Which Bonsai Tree Fertilizer Is Best – Liquid or Granule?

Another factor that may affect which fertilizer is best for growing bonsais is the fertilizer type. 

There are a lot of fertilizers on the market, but you’ll mostly find them in liquid feeds or pellet/granule feeds. 

I tend to find that granule fertilizers are the best option, whether you’re a seasoned or beginner bonsai tree grower. 

However, you should check out the pros and cons of each fertilizer category below to see for yourself. 

Granule Fertilizers

One thing to note about granule fertilizers is that you just sprinkle them on top of your bonsai tree’s soil. 

You don’t need to add water right away or mix water with the granules before applying them. 

Also, granule/pellet fertilizers are slow-release, meaning they dissolve into your soil over time (about a month or two). 

This gradual delivery is gentle on the soil and the bonsai tree, so most people recommend using this kind of fertilizer. 

It also has the advantage of being visible to the eye, so you can tell when it’s about to dissolve completely and run out. 

Liquid Fertilizers

On the other hand, liquid fertilizers are slightly inconvenient to use, and beginners might have difficulty finding success with them. 

Because liquid fertilizers are not slow-release, they are very concentrated, meaning you have to dilute them. 

Thus, you must mix them with water and then apply the mix to your bonsai tree soil. 

In one sense, they’re advantageous because they quickly administer nutrients to your tree. 

Yet, they don’t last as long and can distribute unevenly due to the way that bonsai soil tends to drain. 

Final Thoughts

Many bonsai tree growers face a similar problem either at the beginning of their growing journey or even after years of practice. 

People want to know the best fertilizer for bonsai trees, which is why I created this guide. 

Bonsai trees, overall, need a combination of nitrogen, phosphorus, and potassium (NPK) in fertilizer to support their roots, leaves, and blooms.

Generally, bonsai trees should have a balanced NPK ratio for optimal growth. 

But depending on the season and growing conditions, you may need a different fertilizer ratio to support the plant correctly. 

So, make sure to think about all your choices when picking out the best fertilizer for your bonsai tree.

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