By: Jackie Carroll
Oak trees (Quercus) are among the most common tree species found in forests, but their number are declining. The main cause of the decline is the value of acorns and young saplings as a food source for wildlife. You can help the tree recover its former glory by starting and planting oak tree seedlings following the instructions in this article.
For convenience, the many species of oak are divided into two main groups: red oaks and white oaks. You can tell which group an oak belongs to by taking a close look at the leaves. Red oak leaves have pointed lobes with little bristles at the tips, while the lobes on white oak leaves are rounded.
Propagating oak trees is good for the environment and it’s an easy, fun project for kids. All you need is an acorn and a gallon (4 l.) pot filled with soil. Here are the steps for growing oak trees from acorns.
Don’t gather the first acorns that fall. Wait until the second flush begins to fall, and then collect several handfuls. You might think you are collecting a lot more than you need, but the germination rates for acorns is low, so you need lots of extras. Check the leaves to determine whether you are collecting white oak or red oak acorns, and label the containers if you collect some of each.
Visually examine your acorns and throw away any that have small holes where an insect may have bored in, as well as those that are off colored or moldy. The caps of mature acorns come off easily. Go ahead and remove them during your visual inspection.
Soak the acorns in a container of water overnight. Damaged and immature seeds float to the top, and you can scoop them off and discard them.
White oak acorns are ready for planting right after soaking, but red oak acorns need a special treatment, called stratification. Place the red oak acorns in a zipper bag with moist sawdust or peat moss. You don’t want the sawdust or peat moss soaking wet, just lightly damp. Leave them for eight weeks, checking every two weeks or so to make sure they aren’t molding. Remove molded acorns and leave the bag open to allow fresh air in if you see signs of mold.
Fill pots that are at least 12 inches deep with potting soil. Plant the acorns an inch deep. You can plant several acorns in each pot.
Transplant the seedlings to a permanent location when the first leaves unfurl. If you only have one seedling in the pot, you can keep it indoors in a sunny window for up to three months. If you prefer to plant the acorns directly in the ground, take care to protect them from wildlife.
Early on, oak tree saplings are in danger of being consumed by wildlife. Place cages over newly planted saplings and replace them with chicken wire fences as the sapling grows. Keep the tree protected until it is at least 5 feet tall.
Keep the area surrounding young oak trees free of weeds and water the soil around the tree in the absence of rain. The tree won’t develop strong roots in dry soil.
Don’t fertilize the tree until its second year after planting. Even then, only use fertilizer if the leaves are pale, or the tree is not growing as it should. Keep in mind that oak trees grow very slowly at first. Feeding the tree to encourage fast growth weakens the wood. This can lead to splits in the trunk and broken branches.
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Steve Nix is a member of the Society of American Foresters and a former forest resources analyst for the state of Alabama.
Georgette Douwma / Getty Images
Beginning as early as late August and continuing through December, various species of oak acorns are maturing and ripening for collection. Ripening dates vary from year to year and from state to state by as much as three to four weeks, making it difficult to use actual dates to determine maturity.
The best time to collect acorns, either off the tree or from the ground, is when they begin falling—just that simple. Prime picking is late September through the first week in November, depending on oak tree species and location within the United States. This tree seed called an acorn is perfect when plump and the cap removes easily.
The best time to collect acorns is right after they fall to the ground, usually late September to early November. Oaks are one of the last trees to shed their leaves, and often the acorns fall first. If the acorns are already buried under a lot of leaves, look under trees growing near driveways, parking lots, and sidewalks instead.
The age when oak trees start to produce acorns varies according to each species, and may begin when the tree reaches 10-50 years old.Acorns are produced annually in the fall, but trees may turn out a very light crop, or even skip a year or two after a year of particularly heavy production.Acorns are an important source of food for wildlife, including insects, squirrels, mice, chipmunks, rabbits, deer, chickadees, and quail.Acorns contain tannins that in large quantities, are toxic to horses.
AMES, Iowa – Fall is here, and so are acorns, falling from oak trees into yards everywhere. Viable acorns can be grown into oak trees, if properly handled. How is this done?
Here are some tips from Iowa State University Extension and Outreach horticulturists on how to best handle, germinate and plant acorns. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or [email protected]
It’s common for the acorn crop on oak trees to vary from year to year. Most oak species produce a good crop of acorns once every two or three years. However, the white oak (Quercus alba) tends to produce a good acorn crop once every four to six years.
Weather and other factors can affect flowering and fruiting. For example, freezing temperatures in spring (when trees are flowering) can damage or destroy the flowers, drastically reducing the fruit crop.
The acorns of white oak, swamp white oak (Quercus bicolor), and bur oak (Quercus macrocarpa) mature in one year. Red oak (Quercus rubra) and pin oak (Quercus palustris) acorns mature in two years.
Acorns should be collected as soon as they fall to the ground. Sound, viable acorns can be separated from damaged or unfilled acorns by placing them in water. Sound acorns sink. Most floating acorns are not viable and can be discarded.
The acorns of white oak and swamp white oak should be planted in fall. They 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. Winter weather in Iowa normally provides the necessary conditions to break dormancy. The cold-moist requirement can also be accomplished through a process called stratification. Acorns can be stratified by placing the seeds in a moist mixture of sand and peat moss and then storing them in a cool location.
Suitable containers include coffee cans, plastic buckets and food storage bags. The refrigerator is a good storage location. (Stratification temperatures should be 32 to 41 degrees Fahrenheit.) Acorns of the bur oak require a 30 to 60 day stratification period, while red and pin oak acorns require 30 to 45 days. Acorns of bur, pin and red oaks can be planted in fall or stratified seed can be sown in spring.
When planting acorns, place the seeds one-half to one inch deep. Choose a planting site where the oak seedlings can receive good care for one to two years before they are transplanted to their permanent locations.
To prevent squirrels and other animals from digging up and eating fall planted acorns, cover the area with chicken wire or hardware cloth fencing after planting. Promptly remove the fencing material in spring when the acorns begin to germinate.
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 inch 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.
Few trees are as majestic as the mighty oak. They can live to be 100 years old or more, reach a height of more than 100 feet, and have a top spread that exceeds 100 feet as well. Although they grow slowly, planting an oak tree in your yard is a great project for adults and children alike, and it instills a sense of passing on an heirloom for generations to come. Gathering, preparing and planting acorns to grow your own oak tree requires following a few basic steps.
Gather your acorns from underneath an oak tree. It is best not to pull them from the tree, as they are not mature if they have not dropped yet. If you want acorns from the tree that have not been exposed to ground pests, shake a tree branch and the ones that are ripe will easily fall. The best time to gather acorns is when most of them have fallen from the tree in the fall, and always gather more than you wish to plant, just in case some are not viable seed when you test them.
Remove any acorn caps by gently twisting them off the acorn. If the caps do not come off easily, the acorn is not mature enough to plant. While removing caps, examine the acorns to make sure they have no holes or cracks in them, which can be a sign of insect damage.
Test the acorns by putting them in a jar of refrigerated water for 24 hours. If they sink to the bottom, they are mature, viable seed. If they remain floating on top of the water, they are hollow and will not produce a seedling.
Remove the viable acorns from the water, and plant them as soon as possible. Getting acorns in the ground early gives them a period of cold stratification, which is needed for them to germinate in the spring. If you do not wish to plant the acorn immediately, or you live in a harsh winter climate, you can imitate stratification in your home. If you wish to plant right away, jump to Step 6.
Place the acorns on a paper towel so their outer shell can dry. You do not want the whole acorns to be too dry, as they will need a little moisture during their stratification period. Place the acorns in a plastic baggie and store in the refrigerator until you wish to plant them. Make sure the acorns have some, but not too much, moisture during storage. The best way to do this is to put a piece of damp peat moss or vermiculite in the baggie with them. Leave the acorns in cold storage for at least three months.
Start your seedlings in an area that will be protected from deer, moles and other acorn-loving pests. You can start the seedlings as a group, and then transplant them to their final growing location later.
Prepare the seedling bed by loosening the soil up to 6 inches deep.
Plant the acorns in the soil at a depth of three times their size. If the acorn is an inch long, you will want to plant it 3 inches beneath the soil. Plant the acorns at lease 12 inches apart, and pat the soil down securely over the acorns, and then water well.
Transplant your seedlings in the spring in their final growing location. When transplanting, dig a hole that is 1 foot deep and 2 feet wide. Fill dirt back into the hole, and plant the sapling at a depth where the top of soil will be about an inch above the root line. Add compost if desired, and tap the soil down firmly around the roots of the sapling.
Water well, and keep an eye on the moisture content of the soil around the sapling until it gets established. You may have to water it every two days, especially if your area is experiencing a dry spell.
You can also start seedlings indoors. Plant up to four acorns in a pot that is 12 inches wide by 12 inches deep. Acorns should be planted 3 inches deep into the soil, which should be half potting soil and half soil from your yard. Keep moist, and transplant seedlings outside in spring.
Acorns can remain in cold storage for up to two years, as long as they do not dry out.
Too much moisture during stratification can cause the acorns to become moldy and rot.
For the best results, schedule oak tree planting for either fall or spring. The cool temperatures ease the tree's transition and enable it to develop strong roots.
There are many varieties of oak trees. Here are a few of the most popular varieties planted in the United States. These are hardy for most gardening zones.
Choose a spot for your oak tree that's far enough away from the house, power lines, or outbuildings so that as the tree grows, its branches won't get tangled in anything important and it won't be in danger of falling onto a building. Remember that oaks can grow very large, so space it away from other trees as well, leaving at least twenty feet or more of space between the oak tree and its nearest neighbor.
Of all trees, oaks have strong preferences for their soil. Oaks have developed a symbiotic relationship with a living organism called beneficial mycorrhizal fungi. Mycorrhizal fungi live among the roots of plants and provide plants with minerals and moisture in exchange for sugars exuded by the plant. Tree Help provides a thorough description of this intricate relationship between fungi and oak trees and explains why soils, especially urban soils, may not be adequate for the stately oak. Amend soil with special substances or a heavy application of compost and manure to improve the quantity and quality of the naturally occurring soil fungi.
After choosing and receiving an oak tree from a reputable nursery, garden center or mail order company, select the location for the oak 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. 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.
Acorns are plentiful, and you can easily plant an oak tree from an acorn. Oaks grow very slowly, so it's going to be many years before the tree attains the majestic height you see on mature trees, but you can easily add many oak trees to your landscape this way.
For tips on planting oak trees from acorns, please visit one of the following sites.
There are almost never seedlings growing from acorns. If there were, you would be able to pull them up easily. What you see are sprouts from the roots of the existing tree therefore, you do not want to spray a herbicide on them in an attempt to eliminate the sprouts for you will hurt the “mother” tree along with the sprouts.
Only a small percentage of oaks send up suckers from the roots. It is a genetic trait, like freckles, except I like freckles. But like freckles and sunshine, some trees have the ability to sucker, but do not unless stimulated to do so. Oaks having a slight tendency to sprout suckers will often do so when roots hit a barrier, such as trees confined to a parking lot planter, or between a sidewalk and driveway. Also, when roots are disturbed and damaged by rototilling, they are more likely to sprout suckers. But some trees never will make suckers. When choosing an oak in a garden center, if there are sprouts coming up at the inside edges of the container, I would avoid that tree.
You may choose to mow them along with the grass, if grass still exists. Or if the grass has thinned too much, you might plant Asiatic Jasmine groundcover, and use hedge trimmers to trim the jasmine and oak sprouts to a uniform height. You can cover the area of sprouts with a heavy gauge woven geotextile, and then either mulch or spread large gravel or decomposed granite over the top of the geotextile. My favorite solution, when appropriate, is to cover the ground with geotextile and then build a wood deck.
Or if you prefer a thick green lawn, you may remove the oak tree, and all of the tree roots with a backhoe. If you just cut down the tree, grind down the stump and all the large roots you can see, there will still be thousands of oak sprouts emerging from the remaining roots in your new lawn or bed area for a few years afterwards. The area will need to be continually sprayed with an herbicide.