How Do You Care For Bonsai Seedlings?

If you have started growing bonsai from seed, you have probably noticed that they are extremely delicate and need slightly different care compared to other trees that are older and more established.

I will go through some of the things you need to do and consider to make sure you are caring for them as best as you can, which will hopefully make them strong and healthy.

How Do I Prevent My Bonsai Seedlings From Dying?

Really the secret to keeping your seedlings alive is to care for them properly, which all comes down to balance. You need to get everything just right and it is very easy to do too little, or too much and upset the balance.

You have to remember that your seedlings are extremely delicate and this means they can quickly get in trouble if you get anything wrong. They will be very fragile for a while and your goal is to get them strong enough so that they can start to be treated like the rest of your trees.

I will be covering lot of things below, that if you get correct, should keep your trees both alive and very healthy due to everything being in balance.

Check The Species Specific Care Guide

The first thing you need to do to make sure you care for your seedlings properly is to understand what species they are.

This is really the key to everything as while you can treat a lot of trees in a very similar fashion, knowing the exact care guide for the species you are growing is going to help you significantly.

This is also where a lot of people fall down, as they forget that there is no such things as “bonsai seeds” …the seeds are just normal tree seeds.

The seeds you are growing will become bonsai when you start doing bonsai techniques on them, but until that day, you just have to take care of them and treat them like they are the trees that they are, so find out how to care for the particular species that you own and follow those guides carefully. 

Should You Use A Specific Type Of Soil For Your Bonsai Seedlings?

When it comes to soil, the reality is that a seed will pretty much grow in anything; however, I think you should be using the best soil you possibly can.

When you look across all areas of gardening you will see that most seeds are started in a light airy compost and this is fine, it does pretty well. If you want to use this, you will get results, your tree will grow and as it ages you can then transplant it to bonsai soil … but I would still use bonsai soil, right from the start.  

Bonsai soil will be even lighter and airy and I have found that growing seeds in bonsai soil gives me better roots than growing in pure compost. I find the rootball ends up being a densely packed with fine roots, which is more ideal for bonsai. In normal compost you get longer, thicker roots, which are fine for normal gardening, but you will need to correct this when you start training the tree as bonsai.  

The only caveat I have here is to tell you to use very fine bonsai soil. We actually normally sift bonsai soil to remove the smallest and finest particles as they can get clogged in between the more normal size particles. Although in this instance, it is these smaller particles that you want to use.

The next time you sift your soil, keep the fines and use them for your seeds. Treat these fine particles as gold dust, not waste. I think it is far superior to use this instead of normal compost.

Then when your tree grows and gets a little bigger you can use your normal sized bonsai soil.

Can Bonsai Seeds Be Transplanted Into Larger Pots As They Grow?

When it comes to up potting to a larger pot, there is no real rush for this. You should just treat your seedling like any other tree and decide if it needs repotted or not in the spring.

I would imagine that for the first year it should be fine in whatever pot you started it in, but once it comes to its first spring, you will probably want to put it into a larger pot.

How much root work you do, or what size pot you decide will really depend on your goals and what approach you want to take.

(You can read more about – Starting A Bonsai From Seed – A Guide For Years 1 To 5)

What Are The Climate Requirements For Seedlings Being Grown As Bonsai

Another reason why you need to know what species you are growing is so you can be assured that you are giving your seedlings the correct climate, which is a very important part of their care regime.

While most seedlings need similar climates, this isn’t always the case and the more you know about your trees needs, the better you can accommodate for this.

This is going to become especially important over the winter, when you will need to know exactly what climate they need to remain healthy.

(You can read more about – How Do You Over Winter A Seedling For Bonsai)

Can Bonsai Seeds Be Grown In Any Climate?

In theory, any tree can be grown in any climate, but you may need to intervene and help the tree out in certain circumstances, which is due to the tree having certain needs, as I just mentioned above, but I will go through a few considerations below.

Germination

When it comes to germination, every species will need a slightly different climate, which is why you need to look up what they need.

You may need to give your seeds some cold exposure for a certain amount of time, so you need to know what this is, or you are not going to get the seeds to germinate.

Following the guides is usually very easy …you just need to actually follow them and give your seeds the right conditions to germinate. 

Light

The sun should be able to provide your seedling with enough light, but as they grow and develop, you will find that that some species require a lot more light than others.

Of course the more tropical species will need more light, but they should be able to survive as long as they are getting sunlight. If you really want them to grow to their maximum potential then you may need some grow lights to match their natural climate, although for most people this isn’t necessary, the sun should be more than enough for your seedlings.

(You can read more about – How Much Light Does A Bonsai Need)

Water

When it comes to water, we control this 100%, so it doesn’t matter what the tree needs, we can just give it to the tree.

This does mean that you need to actually learn how to water properly and learn how to read the signs that the tree is telling you.

This may seem like a very easy skill, but it is maybe more nuanced than you may think and will take some time to master it properly. I will talk about this in more detail a little further down.

(You can read more about – How To Water A Bonsai)

Humidity

Some seedlings will need humidity and this again will come down to the species. However, most seedlings do seem to prefer a higher humidity when they are initially growing.

This is why you will see seed trays with plastic domes or guides saying to place seeds in a plastic bag. This locks the moisture in and causes the air to be very humid.

You will need to also be careful when you finally remove this plastic dome/bag as the sudden change of humidity can shock the tree.

This can also happen if you are moving seedlings outside. Taking you time and exposing them to the different environments over the course of a few days is going to really reduce the risk of shock.

Temperature

Most seedlings like it warm, but again, this will depend on the species.

I’ve already mentioned that some seeds may need a cold period, before a warm one to start growing, so all of this information is something you need to find out.

You also need to make sure things do not get too hot as seedlings can very easily overheat and die and of course going to the other extreme; they will not be able to handle the cold very well and will die in frost.

Getting the right temperature is all about keeping things balanced and keeping the seedling at a steady temperature that it is happy with.

Are There Any Pests Or Diseases That Commonly Affect Bonsai Seedlings?

When it comes to pests and diseases, seedlings are equally as susceptible as any other tree, but of course they are very delicate, so if they do get infected with anything they will probably die.

There are also a few diseases that only effect seedlings, such as damping off, which is where the base of the seedling rots and annoyingly its is both common, and incurable.

Mould can also be common on the soil of your seedlings, but this is usually harmless, but it is still something you should try and avoid.

The main way to protect against such problems is to try and keep your trees as healthy as possible by following all the other advice here, but you still may be unlucky and get hit by one of these problems.

Where Should You Place Your Seeds?

Where you place your seeds is an important part of their care as it can really affect their environment and therefore how well they can grow.

Where you decide to place your seedlings is going to depend on what species you are growing, but basically you want to give them an environment they that they can enjoy and thrive in.

You want them to in a place where they can get adequate sun, but not too much as they will be delicate, have a good temperature, humidity and also have some airflow. (Access to water isn’t important as you will be supplying that regardless)

Keeping Your Seeds Inside

You can start all your seeds inside if you want to, it’s not a problem, but of course at some point they will need to go outside, unless they are a tropical species and then they can stay inside all year round.

Usually a bright window is going to be okay for them, just make sure it does not get too hot and that the sun is not too bright, you don’t want to cook your seedlings.

You should keep them warm, but make sure it is not hot, which can come from being too close to a radiator, but also the direct sun as I already mentioned.

As for airflow and humidity, this can be difficult inside, but you easily create humidity by using plastic bag and you can create airflow by fanning some air around your trees. Even doing this once a day is going to help a lot. 

Putting Your Seeds Outside

If you are growing a species that can handle your outdoors environment, then you can start them outside, although you should really only be doing this during autumn, so that they go through your winter and germinate in spring.

If you have started your seeds inside, you can bring them outside in spring to get acclimatised and once they are outside they can stay outside, so long as they can handle your climate. 

Outside is always going to be the best place for seedlings. You lose control of the temperature, humidity and airflow …but nature does a pretty good job of this, so you just have to trust it will be fine.

Overwintering Your Seedlings

You are likely going to have to protect your seedlings over winter, especially if they have not been outside for very long and are not fully acclimatised yet.

If you are growing a tropical species, you can just keep them inside all year round, so you do not really need to worry about them experiencing a winter.

(I have covered how to over winter seedlings in more detail here – How To Decide If You Should Over Winter Bonsai Seedlings (And Where To Put Them))

How Often Should You Water and Fertilise Bonsai Seedlings?

Water is extremely important for your seedlings and is often an aspect of their care that people mess up, as they either give too much, or not enough.

You need to look at your seedlings every day and assess if they need water or not. Do not water on a schedule. Check every day and decide there and then if they need water or not.

You should start to get a feel for how quickly your soil is getting dry, or staying wet and you can then adapt how much you are watering from there. I would still always check every day and your goal is to always keep your seeds damp.

Watering is a tricky skill, but with practice you can learn to read the tree properly and make sure you give it what it needs.

Should You fertilise Your Seedlings?

As for fertiliser, this is something you do not need to worry about for a while. I would totally ignore this for the first growing season, and then when it wakes up after its first winter, you can start introducing it to some fertiliser. 

The roots of seedlings are extremely delicate and fertiliser can be too strong for it. It should also be able to get everything it needs from the soil, so I wouldn’t worry about it for a while, it will be fine on its own. 

What Type Of Pruning Is Necessary For Bonsai Seedlings?

Even though we are growing these seeds to use as bonsai… seedlings are not ready for bonsai pruning.

Really you need to let the tree grow first and this may mean you do not touch it for the first few years. However, if you really are keen to prune, then you can do so after the first winter.

As spring approaches you can prune your tree back …although there will not be much to prune. Your seedling will probably be a 6 inch skinny little stem, and that is it. You can shorten this back, but really it will just cause the single trunk to split into two.

It depends what you want to achieve, but really when it comes to seedlings and bonsai pruning, there is not much happening for a while.

(You can read about – Can Bonsai Seedlings Be Trained To Grow In To Specific Shapes?)

Conclusion

Hopefully this gives you some more clarity around the care needs of your seedling. You should be able to see that the care requirements are a little different to other bonsai, simply as the trees are so small and delicate.

Your goal at this stage needs to be to keep them healthy, and then as they grow and get stronger, you can start applying bonsai techniques to them.

(You can read more about – How Do You Know If Your Bonsai Seedlings Are Healthy?)