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Oak trees are amongst the most popular tree species in the world with well over 600 subspecies such as English Oak, Pyrenees Oak, and Turkish Oak With these trees being so popular globally, there is naturally a lot of crossover with people wanting to bonsai oak tree species. So how exactly do you bonsai an oak tree from an acorn?
To bonsai, an oak tree from an acorn, plant a germinating acorn in perlite potting soil. Grow by watering, maintaining temperature, and protecting your seedling during the winter. After a year, repot and then train your seedling into a bonsai through trunk development, wiring, and pruning.
So what are the advantages and disadvantages of keeping an oak tree bonsai? And what are the major differences between keeping an oak bonsai and other species? Keep reading to find out more!
Bonsai An Oak Tree From An Acorn
Oak trees are incredibly popular.
With an estimated 600 different species of oak trees out there, many want to add these trees into your bonsai collection.
That being said, unlike other tree species commonly used in bonsai such as Olive, Juniper, Jade, or Scots Pine, Oak trees can be a little more difficult to grow.
Luckily, I got in touch with my local botanical gardens, spoke with a few bonsai experts, and even asked 10 plant paladin readers who own Oak bonsai on the best method to grow an oak bonsai tree from acorns.
Here is why they said.
- Ensure it’s the right time of year
- Come up with a design
- Decide how large you want your tree to grow
- Pick your acorns
- Prepare your acorns for oak bonsai
- Invest in the right potting soil
- Plant your acorn in potting soil
- Maintain and care for your tree in the first year
- Move your tree into the right environment
- Repot your tree after one year
- Develop your trunk
- Wire your tree
- Prune the bonsai
- Repeat the process
Some of you will only be interested in some of the quick facts about oak bonsai which is why I have included the table below:
Oak bonsai care
Once per day in the summer, once per week in the winter. Only water if the soil is dry to touch.
4-6 hours of direct sunlight per day.
10 to 84 degrees Fahrenheit (-12 and 29 degrees Celsius)
Outdoors in a birth sunny spot. Indoors with a LED grow light or near a window.
Once per month during the spring/summer
3 to 5 inches per year - slow growing.
Let’s explore this in more detail below.
Ensure it’s the right time of year
More than any other bonsai tree species, when creating oak bonsai the time of year is one of the most important factors to mitigate.
You see whilst training, pruning, and wiring the tree should all be undertaken as early in the spring as possible – to help the tree heal from these activities Acorns can only be collected from oak trees for a few short weeks in the fall.
As such, the planting and growth process of these trees needs to be undertaken much later in the year than you would for other bonsai species.
Now there are ways around this with some reputable retailers selling acorns year-round, however, if growing an oak bonsai from scratch, where you want to source the acorns yourself, you will need to collect these in the fall.
Come up with a design
One of the things I’ve struggled with on my bonsai journey has been growing out bonsai species without a style of bonsai tree in mind.
This defiantly leads to a lot of confusion and it’s no surprise to admit that my first few attempts at creating bonsai didn’t go down very well.
One of the best things then that you should consider when creating an oak bonsai tree from an acorn is to come up with a rough idea of the style and design of your tree.
Bonsai tres, typically fall into several different styles include upright formal/informal, cascade, semi-cascade, or sumo.
Having a plan of what style you want your tree to mimic and drawing this out on pen and paper as early as possible in the process can save you years of heartache later on down the line.
You don’t have to commit to these styles this early and can always change them later on down the line, bit ut this will make the whole design process a lot easier.
Decide how large you want your oak bonsai to grow
Similar to the point above, it’s also important to note who large you want your tree to grow to as early as possible.
Oak trees are relatively slow-growing tree species, growing between 2 to 4 inches per year.
This means that growing a bonsai tree to a larger-sized classification for competitions such as imperial, will take much longer than should you decide to opt for other species.
This will help set realistic expectations and not you will likely cause you to become frustrated when you are a few years into your oak tree bonsai project with only a very small tree.
1 to 3 inches
3 to 8 centimeters
2 to 4 inches
5 to 10 centimeters
2 to 6 inches
5 to 15 centimeters
5 to 8 inches
13 to 20 centimeters
6 to 10 inches
15 to 25 centimeters
10 to 18 inches
25 to 46 centimeters
Chiu or Chumono
16 to 36 inches
41 to 91 centimeters
Dai or Omono
30 to 48 inches
76 to 122 centimeters
40 to 60 inches
102 to 152 centimeters
60 to 80 inches
152 to 203 centimeters
Pick your acorns
Next up is one of the most important steps in growing an oak tree bonsai from an acorn – the picking process.
When to pick up acorns for oak bonsai
As mentioned earlier, first you need to ensure that it is the right time of year.
If acorns are picked too early in the year when they are not ripe then these will fail to germinate.
Alternatively, if these are picked too late in the year, there is a good chance that these acorns will have died.
The best time of year to pick acorns for Oak bonsai would be in mid to late fall. Picking acorns in between September and November will give you the best chance of these acorns germinating allowing them to be used for oak bonsai.
Should I pick acorns off the ground for oak bonsai?
Acorns that you will plant for bonsai use, should not be picked off the ground and instead should be picked directly from oak trees. Acorns picked from the ground may have fallen weeks/months ago meaning they can have a smaller chance of germinating.
How many acorns should you pick for oak bonsai?
When picking acorns for creating oak bonsai trees, between 40 to 60 acorns should be picked from a variety of trees. This is because a lot of the acorns you pick will either be dead or fail to germinate. The more acorns you pick, the higher the chance these acorns have of turning into viable seedlings.
Picking the acorns from different trees will give your acorns a stronger chance of survival.
If the tree fails to produce quality acorns, all the acorns from that one tree will be bad.
Some of these acorns will fail to grow, others will germinate and then fail to grow so picking a larger amount will give you the best chances of success.
How to carry your acorns
When transporting acorns you have picked for bonsai use, ensure you keep them moist. Keeping acorns in a plastic bag or container that you have sprayed with water thoroughly works best to ensure acorns do not dry out.
Sphagnum moss can also be used as a moisture holder for acorns as the moss can hold up to 8 times its weight in water.
Prepare your acorns for oak bonsai
Next up, we need to prepare the 40-60 acorns you have picked to be planted.
Whilst 40-60 might seem like a lot, the next steps will remove a lot of them from the process.
First, gather a bucket and pour your acorns in. Some of the cups the acorns have might fall off but don’t worry as these acorns can still germinate.
Then fill the bucket with water and a few of the acorns will float to the top.
These acorns are dead and so need to be removed.
Once the bad acorns have been removed, place the acorns in a see-through clear plastic bag or container box and place sphagnum moss at the bottom.
This will allow your acorns to have plenty of moisture while they germinate.
Then cover this plastic bag/container within a dark plastic bag or container so no light can penetrate and the acorn does not dry out.
It is in the dark when acorns will start to germinate.
Store this away for about 4 weeks.
After 4 weeks, gently check the acorns every 3 to 4 days to see if any of them have started to germinate.
Here you are looking for any acorns that have sprouted their first root that is about a quarter of an inch.
These acorns can then be potted in the next step.
Invest in the right potting soil
As your acorns are preparing to germinate in the containers a good next step is to prepare the potting soil you will need for your oak tree bonsai.
Whilst most potting soils require three main elements; good aeration, drainage, and moisture retention, oak trees, and acorns require more oxygen than other varieties.
As such, finding a granular soil mix works best for oak trees bonsai varieties.
Using a potting soil mix that contains a large percentage of either perlite or vermiculite works best for growing oak bonsai trees.
A 100% soil mix of either vermiculite or perlite can produce fantastic results for oak varieties, however, you can mix these soil mixes with others such as volcanic ash rock or even peat moss and cactus soil for decent results.
Plant your acorn in potting soil
At this point, your acorns will have started to sprout and you will have chosen the right potting soil so it is time to start planting your acorn.
First, choose a small size pot that is around 3 to 5 (8 to 15 cm) inches deep.
Ensure that this has enough drainage holes – the larger the acorn and pot the more drainage holes you will require – hopefully, the table below will help.
Number of penny-sized holes
Number of pencil-sized holes
1 to 3 inches
2 to 4 inches
2 to 6 inches
5 to 8 inches
6 to 10 inches
10 to 18 inches
Chiu or Chumono
16 to 36 inches
Dai or Omono
30 to 48 inches
40 to 60 inches
60 to 80 inches
Now if you are tight on money, consider using something like an old yogurt pot and drill a few holes in with a pencil at this stage,m don’t worry if you think your pot is too big, you will repot your plant in around a year or so either way.
Then lightly fill the plant pot with a base layer of potting soil.
Place the acorn in the pot, ensuring that the new root is pointing downwards – this will aid in the growth of the tree.
Then top up with the remainder of the potting soil, when your acorn has been potted, the topsoil should be around 1cm above the acorn.
Maintain and care for your tree in the first year
So once your acorn has been potted you need to ensure you give your seedling regular care in its first year.
We will cover watering, sunlight, and fertilizing requirements later in the post but to summerise:
Watering – Your oak bonsai should be watered once per day as a minimum. Ensure you touch the topsoil before watering. If dry water, if it is still damp to the touch, avoid watering as this can cause overwatering.
Fertilizing – Avoid fertilizing your bonsai in its first year. Fertilizing can be undertaken in its second year, once per month in the spring and summer.
Sunlight – Oak Bonsai require 4-6 hours of direct sunlight per day. Use grow lights if kept indoors or place them outside in a bright spot in your garden.
Problems in the first year of keeping oak bonsai
One of the major challenges you might have is that you will have planted your acorn in the fall when they are picked and yet no growth will occur if you keep it outdoors due to winter.
As such keeping your bonsai tree indoors from the fall to the early spring and then moving them outdoors I found to be the best bet for Oak bonsai.
To do this, move your bonsai tree indoors in a room where it can get plenty of light such as on a window sill. Oak trees typically need around four hours of direct unfiltered sunlight per day.
If your winters are particularly cold and harsh then invest in an LED grow light – you will want to ensure that this grows light covers the full spectrum of both red and blue light.
LED grow lights should be kept about 10 inches away from your oak tree if using 50-watt bulbs. These lights should be kept on for about 4 to 6 hours in the winter
Using grow lights in the harsh winters will prevent you from winterizing your bonsai in a very delicate stage and will mimic the spring months giving your bonsai continuous growth in the winter.
To read up more on grow lights – check out my post on the best artificial light for bonsai here.
Move your tree into the right environment
As soon as the early spring hits, in the first year, you can move your tree outdoors to ensure it gets the best out of natural sunlight and temperature.
The best place to keep an oak tree bonsai then would bein a bright spot in your garden where your tree can get 4-8 hours of sunlight per day.
Start by easing your bonsai in the shade for a few days per week and then gradually move into sunlight by the end of the week.
Ensure you keep the temperature of your oak tree bonsai between -12 and 29 degrees Celsius or 10 to 84 degrees Fahrenheit.
Temperature higher than 30 degrees C can dry out, burn, and kill your tree. Temperatures lower than -12C will freeze your tree to the point where it may not be able to recover.
If you live in a climate that has extreme conditions I’d consider investing in something like a bonsai greenhouse to maintain your tree’s temperature year-round.
Repot your tree after one year
After one year, you will likely have a small oak tree that looks like a small thin branch with a few leaves growing on it.
Sadly this doesn’t resemble a bonsai but the good news is after one year of solid growth, your tree should be healthy and strong enough for bonsai development.
Before you start developing your tree it is time to repot your tree as the roots and tree will have outgrown the pot.
Now repotting a tree is a large process all onto itself so I would recommend reading my full post on it here but to summarise:
Remove your bonsai from its existing pot
Use a root hook to go around the edge of your existing pot to remove your bonsai.
This should loosen up the soil and make it easy to remove
Remove the taproot on oak tree bonsai
So one step that is unique to oak bonsai is taproots.
Taproots are centralized gnarly roots that other roots grow off of.
In an ideal world bonsai tree roots will grow as follows:
In reality, however, a lot of root growth comes out of one centralized tap root.
In oak tree species, taproots tend to be notorious for being large and difficult to work with.
When keeping an oak bonsai tree, if we don’t trim down the taproot, any future roots will grow on the taproot as opposed to the base of the bonsai.
If however, you remove the taproot all together there might be insufficient roots for the tree to survive.
To counteract this, start by removing the clump of soil.
Then chop the taproot so you only have about 1cm of it remaining.
Ensure however that there is some root growth above the taproot to prevent your bonsai from dying.
Finally use a copper wire as a tourniquet and tie this around on the top of the taproot.
This will force the bonsai to create new roots above the taproot – when you remove the taproot you can then.
Prepare your pot
Select a larger shallow bonsai pot.
You can use the table I highlighted earlier to get an idea of the number of holes you will need.
Apply a wire mesh at the bottom of the holes to prevent the soil from falling through.
Then thread two copper wires through the base holes/mesh – these should be about 15 to 30 cm long and will be sued to hold your bonsai tree in place.
Place your tree
Finally, add a quick base layer of potting soil, then gently place the oak tree bonsai in the new pot.
Finish off by tying the copper wire to the tree so it does not move and then add the remainder of the potting soil to the top of the tree.
Your oak tree will now successfully be repotted and ready to start trunk development.
Develop your trunk
Now your oak tree bonsai has been repotted into a larger pot, you can start making it look like an actual bonsai tree.
The best palace to start with this would be by creating a wider, thicker tree trunk with plenty of movement and shape.
This can be undertaken in three main ways:
- Bonsai trunk chopping – used to add taper to your tree
- Bonsai trunk bending – used to add bends in your tree – particularly useful for styles like cascade, semi-cascade, or informal upright bonsai styles which have a lot of movement in them.
- Growing out a sacrifice branch – This will thicken up the size of the trunk of the tree over a few years by growing out an excess branch.
Developing a thick, stylish, and tapered bonsai trunk will be vital to transforming your current oak tree into an oak bonsai. As this process can be challenging I would recommend looking at my bespoke post on the topic here.
Just be aware that developing a strong trunk for a slow-growing bonsai species such as oak can take between 8 to 10 years if growing your oak bonsai tree from an acorn.
Wire your tree
After a few years of tree trunk development, you will have a strong tree trunk that will start to resemble a bonsai tree.
Next up then we need to undertake the same process for the branches of your tree.
This is undertaken through wiring your bonsai – again another complicated process that I have gone into more detail on here.
To wire your oak tree bonsai:
Remove any excess foliage from your tree to make it easier to see the branches you are wiring – this can be done with a sharp pair of scissors.
Select the branches of your tree that can be single-wired and then wrap copper or aluminum wire around the trunk of your tree at a 45-degree angle for support and then at a 45-degree angle around the branch you are wiring.
Single wire any secondary or tertiary branches.
For the remaining branches that are near each other, you can double wire these.
Simply wrap your wire around the middle part of the trunk so that it can reach multiple branches and then wrap the branches at a 45-degree angle.
You can then move your branches into their new position.
Remove the copper wire with shears after 6 to 8 weeks – your branches will then be set into their new position.
Prune the oak bonsai
Once your oak bonsai tree has been wired you can then prune the tree using a sharp pair of scissors.
Aim to cut back and branches or leaves that take away from the silhouette of the tree design you are looking for.
Ensure you regularly check your tree every few weeks for signs of new growth and trim them back if need be.
Alternatively, if you want to speed up the rate at which your tree is sprouting leaves or enable new growth for a larger-sized bonsai, consider defoliating the leaves of your oak tree bonsai.
This will create a much thicker denser canopy and lead to much greater bonsai ramification.
Repeat the process
Getting this far is only half the journey and you will likely have to repeat the steps of repotting, developing the trunk, wiring, and pruning in a cycle, every few years to achieve a bonsai you can be proud of.
As oak tree bonsai are so slow-growing this can take upwards of 15 to 20 years until you have a decent-looking bonsai tree so be patient.
FAQ’s on growing oak tree bonsai from an acorn
So now you know the exact step-by-step process of growing an oak tree bonsai from an acorn, there are several common questions you likely still have so hopefully the answers below will help:
How much water do oak bonsai need?
Oak bonsai typically need to be watered once per day in summer and once per week in the winter. Touch the topsoil of your oak bonsai. If dry to the touch the tree needs to be watered If moist to the touch do not water as this can cause overwatering.
Sunlight requirements for Oak bonsai
Oak bonsai need at least 4 to 6 hours of direct sunlight per day. Aim to keep these outdoors in the bright spot of a garden, or indoors near a window or with a LED grow light. Oak bonsai can also be grown in shady spots in the garden.
How to fertilize oak bonsai?
Oak bonsai should be fertilized once per month during the spring snd summer. Oak bonsai should not be fertilized in the fall or winter. Do not fertilize an oak bonsai tree if it is less than 1 year old.
What is the best temperature to keep an Oak bonsai?
Oak bonsai can be kept between 10 to 84 degrees Fahrenheit (-12 and 29 degrees Celsius). Keeping oak bonsai in temperatures higher than this will cause them to dry out. burn and in severe cases die. Colder temperatures will cause your tree to freeze permanently.
Can you grow oak bonsai indoors?
Oak bonsai can be grown indoors if an LED grow light is used. Ensure the light is kept on between 4 and 6 hours per day and kept 10 inches away from the tree if using a 50-watt bulb. Alternatively, keep the oak tree bonsai in a bright spot indoors such as on or near a window sill.
Maintain the tree with watering, fertilizer, and pruning as you would normally.
How often should you repot an oak tree bonsai?
Oak bonsai can be repotted every 2 to 3 years. Avoid repotting oak tree bonsai every year. Do not repot oak tree bonsai within its first year. Older oak tree bonsai can be remitted every 5 to 7 years.
How long does it take to train an oak bonsai from an acorn?
Growing an oak bonsai from an acorn at a minimum will take 10 to 15 years. This is because oak tree bonsai are slow-growing tree species. Developing the tree through trunk development alone will take a few years.
What pests attack oak bonsai?
Aphids, spider mites, scale, slugs, and caterpillars are all common insects and pests that will commonly attack oak bonsai. Avoid insect infestation by using soapy liquid and vinegar.
To read up more on how to stop pests from attacking your bonsai, check out my post here.
Can I grow a bonsai from an acorn?
Acorns can be grown into oak tree bonsai. It takes about 15 years for acorns to mature into oak bonsai. Ensure you pick between 40 acorns to improve your chances of the acorns germinating. Keep acorns moist as your transport them and ensure acorns are only picked from trees and not the ground.
Can oak be used for bonsai?
Oak trees can be used for bonsai trees. These bonsai are amongst some of the most popular varieties of bonsai. Oak bonsai can be grown from scratch with an acorn.
What is the best way to grow an oak tree bonsai from an acorn?
The best method to grow an oak tree bonsai from acorns is to select the right acorns. Ensure you choose at least 50 to ensure your acorn germinates. Pick acorns directly from the tree and not the ground and transport them in a plastic bag with moisture to ensure they do not dry out.
Advantages of bonsai an Oak tree from an acorn
The main advantages of oak tree bonsai are as follows:
- Strong trunks – Meaning that they are less likely to be susceptible to fungal or root infections
- Easy to grow – Acorns can be found pretty much anywhere making them ideal for growing from scratch at an inexpensive price.
- Long-lasting – As these trees are slow-growing they can last for hundreds of years, being passed down from generation to generation
Disadvantages of bonsai an Oak tree from an acorn
Oaktree bonsai also has a few significant downsides including:
- Slow growing – These trees only grow between 2 and 5 inches per year meaning that it can take decades until you have a mature bonsai tree.
- Harder to train – Oaks agave strong wood meaning that the branches and roots will be more difficult to maintain and manage than in other varieties
- Taproot – Oak trees are notorious for having strong taproots. Failing to remove these correctly can kill your oak bonsai during the repotting process.
Study on bonsai an oak tree from an acorn
Finally, I did a quick survey of 10 plant paladin readers who own oak bonsai and asked them if they were easy to grow.
Here were the results:
This post was written by Fehed Nicass who has been passionate about bonsai for over 3 years.