Hi,
This is a really interesting and often overlooked question. Growing bonsai is a real skill and can become an obsession. I've grown a few bonsai in my time but with work commitments have had to slowly give up as I couldn't give them the attention they need. Also leaving bonsai with friends to look after can both ruin your mini tree and friendship!
Bonsai tree seeds are sometimes sold as specialist seeds. However, these are just seeds of the full-size tree. The art of bonsai is the pruning and control of these trees into their microform.

Getting a seedling into the form of a bonsai will take at least 5 years so it really is a labour of love. That said, definitely give it a go as you will learn so much about the trees, pruning and patience with germination. So a great activity for an enthusiastic gardener! Bonsai would become fully formed trees if left to grow and so most will only survive if there's some access to the real outdoors. In China, I've seen them displayed on plinths outside in gardens then brought in for weeks here and there to be enjoyed inside.
When is the best time to germinate bonsai seeds?
The best time to sow any tree seed is during its dormancy period like the wild. Seeds often have to survive long cold winters before they germinate in the spring. I once grew a fir from a seed into a bonsai before it sadly died due to lack of care from a friend when I went on holiday. (It wasn't her fault given how challenging bonsai are to the inexperienced -she waterlogged it and it died).
Sow your tree seeds late winter - December here in the UK. You want to mimic the latter part of winter.
Some seeds will need stratification - where you mimic freezing or low temperatures to engage them to awaken and germinate. Place these seeds in a fridge for 2-3 weeks before sowing them.
https://youtu.be/DICGT44SMSs
Other seeds need scarification to break down their tough shell or seed walls. Do your research on the seeds you have to see if either of these are needed. For birch, I don't think you do but Fir or Pine it may be different given their usual environments.
How to sow bonsai seeds:
My advice with all seed sowing is to use special seed sowing compost that's low in nutrients. For tree seedlings add in some perlite to help drainage. No seed wants to sit drowning in high nutrient compost.
You want to sow the seeds onto damp compost and then cover with some polythene or even better, a sheet of glass to avoid using single-use plastic.
Then pull back the see-through cover at least once a week for fresh air and to check the moisture content. I prefer to water from below with these seedlings ie from a tray, once the compost looks like it's going to dry out. Damp but never sodden!

Bonsai Seed Germination:
These seedlings may take 2 weeks to 2 months to germinate so please be patient. They will emerge just as the conditions favour their needs. ie spring temperatures etc.
Once they have germinated and have 2 true leaves - not seed leaves which are the first pair to emerge, then prick them out and pot them on into normal compost. You don't need to cover them any more but put them somewhere with a decent light source but out of direct heat.
https://youtu.be/WqMLFIsklBE
Bonsai Pruning Overview:
For the first year you'll just be getting the seeds to germinate and become healthy mini saplings. 3-5 inches tall.
Year 2: Transfer to a larger point with specialist bonsai compost and start the basic structure of the tree keeping it reduced in height if it starts to really put on growth.
Year 3: Start with the frame work of the branches for its ultimate shape.
I really would recommend a book on bonsai pruning to get the hang of it or attend a day course somewhere. It's both a science and an art. I'm not the expert at it by any means.
Year 4 onwards: regular bonsai pruning and tweaking.

Although it sounds like a royal mission - which is can be - growing and keeping bonsai is fun if you like control, rules and patience. Give it a whirl and enjoy the process!
Happy growing.
Lee
Hi,
This is a really interesting and often overlooked question. Growing bonsai is a real skill and can become an obsession. I've grown a few bonsai in my time but with work commitments have had to slowly give up as I couldn't give them the attention they need. Also leaving bonsai with friends to look after can both ruin your mini tree and friendship!
Bonsai tree seeds are sometimes sold as specialist seeds. However, these are just seeds of the full-size tree. The art of bonsai is the pruning and control of these trees into their microform.

Getting a seedling into the form of a bonsai will take at least 5 years so it really is a labour of love. That said, definitely give it a go as you will learn so much about the trees, pruning and patience with germination. So a great activity for an enthusiastic gardener! Bonsai would become fully formed trees if left to grow and so most will only survive if there's some access to the real outdoors. In China, I've seen them displayed on plinths outside in gardens then brought in for weeks here and there to be enjoyed inside.
When is the best time to germinate bonsai seeds?
The best time to sow any tree seed is during its dormancy period like the wild. Seeds often have to survive long cold winters before they germinate in the spring. I once grew a fir from a seed into a bonsai before it sadly died due to lack of care from a friend when I went on holiday. (It wasn't her fault given how challenging bonsai are to the inexperienced -she waterlogged it and it died).
Sow your tree seeds late winter - December here in the UK. You want to mimic the latter part of winter.
Some seeds will need stratification - where you mimic freezing or low temperatures to engage them to awaken and germinate. Place these seeds in a fridge for 2-3 weeks before sowing them.
Other seeds need scarification to break down their tough shell or seed walls. Do your research on the seeds you have to see if either of these are needed. For birch, I don't think you do but Fir or Pine it may be different given their usual environments.
How to sow bonsai seeds:
My advice with all seed sowing is to use special seed sowing compost that's low in nutrients. For tree seedlings add in some perlite to help drainage. No seed wants to sit drowning in high nutrient compost.
You want to sow the seeds onto damp compost and then cover with some polythene or even better, a sheet of glass to avoid using single-use plastic.
Then pull back the see-through cover at least once a week for fresh air and to check the moisture content. I prefer to water from below with these seedlings ie from a tray, once the compost looks like it's going to dry out. Damp but never sodden!

Bonsai Seed Germination:
These seedlings may take 2 weeks to 2 months to germinate so please be patient. They will emerge just as the conditions favour their needs. ie spring temperatures etc.
Once they have germinated and have 2 true leaves - not seed leaves which are the first pair to emerge, then prick them out and pot them on into normal compost. You don't need to cover them any more but put them somewhere with a decent light source but out of direct heat.
Bonsai Pruning Overview:
For the first year you'll just be getting the seeds to germinate and become healthy mini saplings. 3-5 inches tall.
Year 2: Transfer to a larger point with specialist bonsai compost and start the basic structure of the tree keeping it reduced in height if it starts to really put on growth.
Year 3: Start with the frame work of the branches for its ultimate shape.
I really would recommend a book on bonsai pruning to get the hang of it or attend a day course somewhere. It's both a science and an art. I'm not the expert at it by any means.
Year 4 onwards: regular bonsai pruning and tweaking.

Although it sounds like a royal mission - which is can be - growing and keeping bonsai is fun if you like control, rules and patience. Give it a whirl and enjoy the process!
Happy growing.
Lee