We all know the benefits of trees, if you really don’t, have a look around the website!
How to plant an acorn and grow an oak tree with your children.
Planting an Acorn and growing an Oak is quite a simple thing to do. It is something that you could easily do with your children; it is a fun thing for children to do on their own, too.
With over 400 species of Oak, there could be the possibility that you collect and acorn that this process will not work for. There are a few variances that I am aware of – look out for the red oak needing a longer rest period before it germinates.
In case you aren’t sure what an acorn looks like – they are typically like this
though they can vary in size
When do you collect acorns?
Depending on the species of Oak, we can find acorns beginning from early August through to December maturing and ripening ready for collection.
This varies from year to year depending on that year’s weather through the seasons and can affect the dates by as much as four weeks.
It is best and easiest to collect the acorns when they have just fallen off the tree.
Tip: Look for Acorns that have already germinated – this can happen – it gives you a head start!
What makes a good acorn?
The perfect acorn is plump, and we can easily remove the cap.
Discard any acorns that have cracks or holes in the shell.
A great way to test for good acorns is to leave in a bucket or pot of water for 24 hours. If it is still floating after that time, discard it.
Critically, do not allow the acorns to dry out, and while they are in storage, they must not get warm. Both these factors will kill off the acorn quickly and germination will not happen.
Tip: Gathering acorns from several trees will increase the chances of success .
Germinating the Acorn
We now have 3 options to germinating the Acorn. All with varying amounts of success and involvement.
- Plant the acorn where we want the oak tree to grow. Once planted there is no more involvement assuming that the soil remains moist, though this follows the natural process, this is probably the least successful.
- Plant the acorn in a post of potting compost. We can keep the pot moist and sheltered.
- We can add an extra process step where we hibernate the acorns – this requires a little more involvement but can up the success rates.
The following steps assume you are going to go for option 3. With options 1 and 2, keeping them outside will subject the acorns to the natural conditions.
Hibernate the Acorns
You need to put your acorns in a large zip-lock bag with moist sawdust or similar (e.g., compost or moss). It is important that the material you pick can hold moisture. You should be able to hold many acorns in this bag – we don’t need to bury the acorns, just keep them moist.
We then need to put the bag in the refrigerator
Tip: don’t seal the bag completely – the acorns need to breath – a small gap will suffice.
Putting the acorns in the refrigerator triggers a process called stratification, which is simply the name given to exposing a seed to cold temperatures. This is simulating winter for the acorn and triggering its natural processes.
You must check the bag regularly to ensure that the sawdust (or other material) is moist, you want it to be damp, not wet. The moisture is to stop the acorns drying out, but don’t make it too wet or they will rot.
Tip: Even in the fridge, some of the acorns can germinate, so take them out very carefully so that you don’t break the root.
A fun extra step
You could just plant the acorns now. But where would the fun be in that, especially if you are doing this process with your children?
They won’t be able to see any acorn planted in the dirt. As mum has already had to put up with a bag of acorns in the fridge, you might as well make the extra effort with this additional step, an exciting way to see the first stages of growth, for at least a few of your stash of acorns.
The true benefit of this step is that it improves the odds of success.
- Take one of your acorns – one that has not yet sprouted – and carefully insert 3 cocktail sticks, equally spaced around the circumference, halfway between the top and bottom.
- Set the acorn on the top of a small glass or jar, an old jam or pickle jar is ideal. You want the acorn to be balanced in the middle of the jar opening with the cocktail sticks balanced on the rim.
- Carefully, fill the jar with water, so that the bottom of the acorn is submerged.
- Put the jar in a warm, sunny spot like a windowsill – sorry mum!
As the acorn germinates, you should see a large tap root appearing, which will grow down from the acorn into the jar.
Once the acorn has established tap root, a green shoot should appear from the top of the acorn.
Tip: If you leave the germinated acorn a while, there is a chance you will see the leaves start to grow in that familiar shape.
By Amphis - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20049624
Planting the Acorn
Obviously, you could plant the acorn in the ground at this point but again to improve the odds of success it makes sense to plant it in a pot
Additionally, to improve chances of success further the deeper the pot, the better. If the tap root has plenty of space to grow, the stronger the sapling will grow. If the root grows into the bottom of the pot, it might get damaged.
The perfect pot for your acorn
An excellent alternative to a traditional pot might be to use a large juice or milk carton. Make sure that you rinsed out the pot well and open up the top completely. It might be worth cutting the top with scissors to make it look tidier.
Make sure that you make some small holes in the bottom for drainage – just in case you accidentally over water it, we need to create an environment that is moist, not a swamp.
- Fill the container with soil, leaving 2 inches at the top free. It is best to use soil similar to that of the planting location of the Oak over potting compost.
- If your acorn has germinated, plant it root down, making a small hole to feed the root into, being very careful not to damage it. The acorn should just be on the current soil surface.
- Using your fingers, push into the soil and squeeze it gently towards the root so that the hole you created for the root should be filled in.
- Now cover the acorn by adding more soil, about an inch of soil is ideal.
- If the acorn has already sprouted, you want to allow that to poke through the soil and not bury it, so this might mean that the acorn is only just below the soul level.
- Gently water the soil around the acorn.
Tip: Ideally put the pot where it will have sunlight in the morning but shade in the afternoon.
How often do you need to water the acorn?
You must not let the soil where the acorn is planted dry out
You will probably need to increase the frequency when days are sunnier and warmer moving into summer.
Try not to over water. Even though the soil on the surface may look dry, the soil underneath might be moist enough. Check by pushing your fingers into the soil to check. Remember, you don’t want it too wet, there is a risk that the acorn could rot instead of root.
Tip: If you planted your acorns in pots, move them to a raised area– water until you see the water coming through the drainage holes – leave for 10-15 minutes to drain before putting the pots back in their resting place. You don’t want the pots sitting in the drained water.
How long does it take for an acorn to germinate?
Acorns grow their root first; this is usually quite a while before the shoots appear. It depends on the climate the acorn is in (heat and water).
Acorns will typically germinate 2-4 weeks after being planted often sooner if you use the jar technique.
The acorn will grow a strong tap root before the first shoots will appear.
Typically, the first shoots will appear -8-10 weeks after planting. Most acorns should be showing shoots by 14 weeks. A gain the jar technique described above will often lead to faster results.
How long should I wait until I plant the Oak Tree Sapling?
A lot of gardening sources differ in their recommendation of what to do once you have a sapling. Overall, I think that this is down to the fact that it really depends.
The Oak sapling needs to have good conditions, so it really depends on where it is likely to get the best conditions to allow it to thrive.
It needs moist, well-drained soil. It needs warmth and the right amount of sunlight.
Some garden sources recommend planting it in the ground straight away, others suggest you leave that until the autumn, or maybe waiting longer until you have a sapling that is over 15 cm tall, where you have transplanted it into larger containers as required.
I think that the longer that you leave it in a pot until the sapling is more established is a better option. However, this relies on the fact that it must be maintained well. It must be watered frequently, must be not allowed to get too hot or too cold to ensure its success.
The other advantage of keeping it in the pot is that you can have several saplings growing and then finally plant the one that is the most successful or appropriate for the space that you have chosen. Like wise keeping it in the pot might give you the opportunity to find a more suitable spot that is better for the long term, knowing that it will have the ability to grow successfully for a long time and be the home to wildlife.
Tip: It is best to plant an Oak when it is more dormant – this is fall to winter time – they tend to be more resilient to being moved at this time.
Oak tree saplings that are good for planting
Good candidates for transplanting are:
- Are at least a few weeks to several months old
- Have shown substantial tap root growth
- Have white, healthy looking roots
- Appear to be out growing their current container
- Are about 10-15 cm (4-6 in) Tall with some small leaves.
Av Max Ronnersjö - Eget arbete, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=25573891
Where is the best place to plant an Oak Tree Sapling?
You want to plant your sapling in a spot where there is plenty of room for the tree to spread not only its roots but also its canopy.
Most varieties of Oaks can grow very tall with a large root system, so you want to make sure that you plant far from any buildings or underground pipes.
Research how tall your variety of Oak is likely to grow and then use the 4:1 rule. So, for example, you have a variety that is likely to grow 80ft tall then plant it at least 20 ft away from any buildings.
Tip: The more space, the better.
How do I plant my Oak Tree Sapling?
I’ve written an article all about planting trees which you can find here
However, here are some quick pointers
- Dig a hole about the same size as the container the seedling was in.
- Assuming your sapling is still small, unlike planting a larger tree, there should be no root issues requiring a larger hole.
- Remove the entire contents of the container and place in the hole.
TIP: If you let the soil dry out a little, it should pull back from the sides of the container and slide out easily.
- Make sure that the top of the container soil is at ground level; don’t plant it too deep.
- With the leftover soil from digging the hole, you can make a small ring around the tree, about a foot away from the stem.
- You can also put down some mulch, but make sure not to put any too close to the seedling’s stem. Doing so may cause an increased risk of disease or water-logging.
- Placing a flag nearby will help you remember where the seedling is and keep it from possibly getting mowed down.
- If you are worried about animal activity or other damage, you can use a tomato cage or similar fence to protect your seedling as it grows.
- Once it has grown about 18 inches tall, you can remove the cage.
- Be sure to keep the growing young tree watered and monitor it for signs of insect activity.
Growing an Oak Tree sapling from an acorn as you can see can be pretty easy.
Not only that, it’s fun to do with the children, most of which they can do on their own if you point them in the right direction.
The only downside is that if your children are anything like I was, I want to see the results quickly rather than having to wait for 12 weeks before I see anything.
I found this really great animation on YouTube, that follows steps that are like those that I have described. It might be useful for you and them to see to see the process steps.