Everything You Need to Know about Growing Oak Trees from Acorns
Oak trees are beautiful, drought-tolerant, native trees with many benefits for wildlife and people. They are also popular trees. Ever wondered how to plant an oak tree from an acorn? It’s easy!
Oak trees can be planted from acorns with great success if proper steps are taken. Late fall is the perfect time of year to collect acorns to start growing new oak trees over the winter. Acorns that have dropped earlier in the fall are usually the weaker or worm-infested seeds. Late dropping acorns (October and November) are typically healthier. A healthy acorn specimen suitable for growing an oak tree is one that is plump with a cap that is loose and/or easily removed. A naturally split or cracked acorn is fine, but do not collect damaged, crushed or moldy acorns. Avoid acorns with a pinhole on the shell. This is a sure sign that a worm has bored into the nut.
Once you have your acorns fill your pots with potting mix. Place two acorns sideways in each pot, at a depth about three times the width of the acorn, or about one inch. Water them well until water runs out of the drainage holes.
Place your potted acorns in a sunny spot and sheltered from the wind. Planted acorns spend their first few months sending down a long tap root, so don’t expect to see any above-ground growth until March or later.
You have the basics of planting oak trees from acorns but let’s dive into the details so that you will have the best germination and highest success.
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Collection-
It is best to collect native acorns in early November before they have fallen to the ground. Scope out some good, healthy trees for collecting during the late summer so you are ready when they are. They are ready when they can be removed from their caps without tearing them.
Processing-
Fill a bowl with cold water and place the acorns in it. Viable acorns will sink or remain at the bottom and damaged or empty ones will float. Discard the floating acorns. Briefly soaking the acorns also helps rehydrate them if you stored them before planting.
Planting-
For the best success, acorns should be planted in December or January, after the rainy season has started.
One of the major causes of oak seedlings’ death is predation by small rodents, therefore protecting your seedlings is important. Plant acorns in a milk container with the top and bottom cut off or in a commercially available tree protector. This will also allow you to keep track of where the acorns are planted and protect them from rodents. Use pots deep enough for root growth. A gallon container is ideal.
Fill the pots with potting mix. Place two acorns sideways in each pot, at a depth about three times the width of the acorn, or about one inch. Make sure there is at least one inch of soil covering your acorns. Water them well until water runs out of the drainage holes.
Place your potted acorns in a spot that gets full sun and is sheltered from the wind.
Learn More About Sun Mapping HERE.
The acorns of white oak and swamp white oak will germinate immediately after sowing. Acorns of bur oak, pin oak, and red oak will not germinate until they have been exposed to cool temperatures and moist conditions for several weeks.
Planted acorns spend their first few months sending down a long taproot, so don’t expect to see any above-ground growth until early spring (March or later).
Regardless of when the acorns germinate—in fall or spring—if both acorns in a pot germinate, cut off the weaker of the two seedlings about one to two weeks after the seedling emerges. Do not pull out the second, unwanted seedling because its root system will be entangled with the roots of the stronger oak.
How long does it take to grow an oak tree from an acorn?
The acorns of some acorn species—white oak, swamp white oak (Quercus bicolor), and burr oak (Quercus macrocarpa)—mature in one year, while for other oaks—red oak (Quercus rubra) and pin oak (Quercus palustris)—it takes two years 2.
Can I plant an already sprouted acorn?
Yes, you can. Place it sideways in the soil with the primary root (radicle) downwards, and be careful not to break the root tip.
There are round, small holes in many of the acorns on the ground. What made the holes?
The small, round holes on the sides of the acorns were likely caused by the larvae of the acorn weevil.
The adult acorn weevil is a brown beetle about three-eight inches in length and has a long, thin snout. Adult females lay their eggs inside developing acorns on trees in mid-summer. The eggs hatch into creamy white, grub-like larvae that feed inside the acorns until fall. In fall when the acorns have fallen to the ground, the fully grown grub chews a round one-eighth inch hole in the side of the acorn, exits the acorn, and tunnels into the soil to complete its development.
Squirrels and other wildlife eat or stash away the good acorns, leaving the “holey” (destroyed) acorns on the ground.
How to Plant an Oak Tree
When the seedlings are about five to six inches tall, or when the root system starts to reach the side of the container, transplant the seedlings to a larger pot with large drain holes. Fill the pots with a mixture of half potting soil and half garden soil and add one teaspoon of slow-release fertilizer to the soil.
Relocate to Permanent Spot
Once the root system is growing out of the drain holes, it’s time to plant the saplings in their permanent location. Select a planting site for your oak tree making sure it has plenty of room to grow into a magnificent tree.
Dig a hole twice as wide and deep as the root ball. The root ball may be wrapped in burlap or another covering. Remove the covering and place the tree in the hole. Be sure the tree is standing straight and tall. Add or remove soil to ensure the tree is tall. Mix a good compost in with the soil you’ve removed from the planting hole, then fill in the hole, tamping down the soil with your shovel or foot until it’s firm. On top of the soil put an organic mulch to help retain water but make sure the mulch doesn’t touch the trunk of the tree. Water thoroughly, allowing the water to really soak into the ground. After planting, spread mulch around the base of the tree. Be sure to water the tree weekly, especially through the hot summer months, if less than an inch of rainfall per week is available.
How far should oak trees be from a house?
This question all comes down to tree size. After all, the wide-root oak tree that’s 70 feet tall needs much more room than the modest Japanese maple. A good rule of thumb is to start at about 8 to 10 feet away from your home for small trees and scale up to account for the tree’s mature height and spread.
How much does an oak tree grow in a year?
A white oak’s growth rate is considered “medium”, growing between 1 foot and 1 and 1/2 feet per year. As trees mature at around 20 years, a 10-year-old oak tree size could be anywhere between 10 feet and 20 feet tall, but this varies.
Oaktree acorns from our yard in Maryland have a special place in my heart. What can I say, I am a sucker for a plant with a history.
To check out the oak trees in our yard and to see how our seedlings are doing be sure to follow us on Instagram.
