Even if you know how to plant a tree the right way, there are some types out there that need special treatment. And this is one of them! Conker trees, known by the common name “horse chestnut,” are popular decorative trees in the UK, Ireland, Canada, and Norway. “Conkers” are those dark chestnut-like nuts that grow inside spiky husks on such trees.
You can collect fallen conkers and plant the nuts to start your own tree! These trees give dappled shade and provide honey and pollen for bees and other insects, making them an excellent addition to a home garden. Below, you will learn how to grow a conker tree and how to care for it.
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About conker trees
Horse chestnut trees (Aesculus Hippocastanum), are native to the Balkans, but they arrived in the UK in the 16th century. They are now ubiquitous throughout the UK and North America as a result of widespread decorative planting.
They are deciduous, large and fast-growing trees similar to buckeyes and can reach heights of up to 30 metres. It is appreciated as an amenity tree because of its beautiful blooms, which appear in early June each year, and its distinctive fruits known as Castanea, which ripen in September.
According to the National Forest Inventory, there are about 470,000 trees in the UK. However, the majority of these trees are found in non-wooded areas. Horse chestnut is a small but important part of British woods.
The majority of horse chestnuts in the UK are probably not counted in any national tree census, but they are common as amenity trees along streets, in parks, and in gardens. Individual trees, both planted and self-sown, thrive along roadsides and in hedges.
How to grow a conker tree step-by-step
If you want to grow your own tree, you’ll be happy to know that we have gathered all the steps for you. Take a look!
1. Gather fallen conkers during the autumn
Look for trees in your neighbourhood’s parks, gardens, roadways, and green spaces. During the autumn, look for the green prickly husks that contain the brown nuts on the ground near the trees.
2. Remove the little brown nuts inside the prickly husks by prying them open
These nuts develop inside a prickly green outer shell that protects them from the elements. If it is still closed, pry it open with your fingertips and pluck out the brown, firm nuts from inside.
If the nuts have been on the ground for some time, the husks may have detached from the nuts. In either case, you only need to plant and brown nuts. Any part that can’t be used, can be discarded or added to a compost pile.
3. Fill a bucket halfway with water and drop your conkers in
Fill a bucket or some other container of water such as a jar so that all the brown nuts that you collected can be fully submerged in water.
4. Discard any nuts that float to the top of the water
Those that float have dried up and are no longer alive. Therefore, they will not grow. You may either leave these nuts outside for animals to eat or compost them. Gather the rest and remove them from the bucket’s bottom and set them aside for planting.
5. Plant your seeds in late autumn (October) before the first frost
They will only germinate after being exposed to cold temperatures for several days. Plant them between the end of October and the beginning of December to ensure that they receive a head start before the cold winter weather sets in. After you plant the nuts, they will germinate and grow the following spring.
6. Fill a small container halfway with soil and compost
Select a small pot with a capacity of 2 L or less. Fill it halfway with a mixture of 50-70 per cent rich potting soil and 30-50 per cent compost, right below the rim. Level out and compact down the top layer of soil using your hands. A loamy soil, which is primarily made up of sand, silt, and clay, is a good rich potting medium for such a tree.
7. Dig a 2 cm deep hole for each seed
With your fingertips, make a small hole in the centre of the pot. Cover the seed with soil after pressing it down into the hole until it is about 2 cm below the surface of the soil.
You can start growing numerous seeds in a single pot, but you’ll need to transplant them sooner. To save time and effort, plant nuts one at a time.
8. Place the pot outside where it will receive at least 4 hours of daily sunlight
Choose a shady or a partially-shaded location in your yard, garden, patio or balcony. Also, make sure that this location doesn’t get too cold during the winter months. If you live in an area where heavy frosts occur frequently during the winter, you can safeguard the pots by placing them in a cold frame. If you want more information on how to protect your plants against frost, then check our guide.
9. Water the soil on a regular basis to keep it moist
Regularly inspect the soil and water it if it begins to dry out. Never allow it to entirely dry out. If the soil does not feel any dryer than it did the previous time you checked it, don’t water it right away to simply avoid overwatering.
10. After you’ve planted the seeds, wait for them to sprout in the spring
Germination of such trees will take roughly 2 to 3 months in cold temperatures. They’ll start sprouting after that. While you wait for the seeds to sprout, don’t make any changes to the water or light conditions.
11. Transplant the seedling when it reaches a height of 0.3 m
Continue to water and monitor your potted plant throughout the spring, summer, and autumn after you’ve planted it until it reaches a height of at least 0.3 m.
It normally takes approximately a year from the time you planted it to see results. You can simply transplant the plant to a bigger pot if you want to keep it growing in one for longer before planting it in a permanent place.
12. Replant the tree in a wide-open area after digging a hole
Choose a broad, sunny spot in your backyard, garden, or field to plant horse chestnut trees permanently.
Dig a hole roughly the same depth as the pot it’s in now, but 2-3 times bigger. Remove the tree and its root ball from the pot, place it in the hole upright, and cover it with soil. Once the tree is planted in the open, your job is done and simply let nature do the rest.
When is the best time to prune horse chestnuts?
Early spring to mid-summer, and late summer to mid-winter, are the best times to prune horse chestnut trees. Consider what you want to achieve before you prune the tree. If you want to keep the tree’s height down, prune when the leaves have fallen off in the autumn to mid-winter. Trimming, on the other hand, can be done at any time of year with very little effort.
Here are some extra tips so you can help your tree grow and flourish:
Horse chestnut tree propagation, like many other trees, will take time and a bit of patience. Seeds or cuttings can be used to achieve this goal. To guarantee that the seeds are fully grown and viable, wait until they have naturally fallen from the tree before collecting them.
Choose seeds that are devoid of cracks and holes, as well as any other symptoms of insect damage. Wear gloves and restrict your exposure to horse chestnut seeds as much as possible, as the seed contains chemicals that can irritate the skin.
Both full sun and partial shade are suitable for this tree. Every day, it needs at least four hours of direct, unfiltered sunlight.
The horse chestnut may grow in a variety of soils, including acidic, damp, loamy, sandy, and silty soils. However, the soil should constantly be kept moist and well-drained. You can also add mulch for increased moisture levels.
These trees don’t like it when it’s too dry, and they do best when they are well watered. After planting, make sure to water well, and then give the new plant a good soaking once a week during the summer (unless rainfall is plentiful).
5. Temperature and humidity
Early to mid-May is when the tree blooms. A commercial quality tree wrap, which is recommended at least for the first two or three years of growth, can be used to protect young trees in the winter.
It works effectively on new trees. Fertilisers that are granular, liquid, or stake-type can be used here. Manure and other organic fertilisers might also produce positive outcomes.
Potential threats and conservation
It has been found that these trees are sensitive to fungal infections. They can be impacted by bleeding canker, which can cause them to die.
The horse chestnut leaf miner can be seen in large numbers on trees, causing the leaves to darken and fall prematurely. There is no indication that this causes harm to the tree because the majority of the damage happens late in the season, but it does alter its appearance.
Horse chestnuts are also susceptible to the scale insect and the fungus Guignardia, which produces leaf blotch.
Now that you know how to plant your own tree and how easy it can be, you might want to start more than one. Imagine how excited your child will be when they see the tree grow 30m high! Cool right? So, what are you waiting for? Grab your gardening tools and get out there!