Acorns to Oaks

Originally published in September 2013

How many acorns will survive and become mature oaks?  Even if none survive, the project will not be a failure, but a success, because the land had someone caring for its future.

Evergreen Park, Minnetonka, MN

There is a multitude of 100 year-old bur oaks in Evergreen Park near my home. However, there are no seedlings that will take the place of these old oaks when they are blown down or die from oak wilt. So what will this park look like in 50 to 100 years when the oaks die out? Buckthorn, box elder and green ash are not valued replacements to the majestic bur and red oak.

My neighborhood

One of my neighbors is looking into the future and is protecting a young oak.

When I look around my neighborhood it is easy to see that this was originally a bur oak savannah. However, many of my neighbors, including myself, have not honored the land. We have planted lawns, where there was once a forest floor; we mow down seedling oaks; we rake up the leaves that would normally breakdown and feed the forest; we plant trees that don’t belong in a bur oak forest, like white pine and spruce.

What to do?

Acorns to Oaks

Red Oak acorns on the left and Bur oak acorns on the right.

About 1 week ago the bur oak acorns began to fall like rain on my roof (Aug. 7, 2023). In mid September, the red oaks acorns will begin falling. Red oak acorns take two years to develop on the tree, while white and bur oak acorns take only one year to develop.

White or bur oak acorns should be planted within a week of dropping or kept in the refrigerator, until planted. The red oak acorns need a period of cold storage, called stratification. They may be placed in a plastic bag and left at a temperature slightly above freezing for a period of 4-8 weeks. They can be planted the following spring.

I did not use the acorns with holes made by the acorn weevil.

I selected the largest dark acorns I could find. If they had insect holes from acorn weevil larvae or were cracked, I did not use them.

The floaters are hollow and will not germinate.

To determine whether the acorns were viable, I put them in a bucket of water for 15 minutes. The ones that floated, I scooped out because they were hollow and would not sprout.

acorn weevil larvae

The sinkers were the ones I kept for planting. I did this for 3 days and each day there were a few more acorns that floated. There were some acorn weevil larvae which had come out some of the acorns and were laying in the bucket.

important note: If you are going to plant in a park, work with your city forester or natural resources manager and develop a plan for your project.

A decade ago, I planted over a thousand a acorns in my neighborhood. This year my goal is to plant 50 bur oak acorns. When you plant an acorn, dig them into the ground about 2-3 inches.  If I see a small buckthorn, I’ll pull it up and pop an acorn in the hole. Next year when the seedlings develop leaves, I am going to have to find a way to protect them from rabbits and deer. I am thinking chicken wire tubes might be the way to go.

The acorn weevil has an interesting life cycle. The adult acorn weevil makes a hole in the developing acorn and lays an egg. The weevil larva hatches and eats the developing acorn. When the acorn falls to the ground, it triggers the larva to leave the acorn. The larva will live in the ground 1-2 years and then emerge as an adult.

I wanted to find out how many acorns were infested with weevil larvae.  I collected 100 acorns to determine what percent of the acorns were infested with weevil larvae and will not sprout. After three days, only five acorns floated (so 95% of the acorns were capable of sprouting).

There are many predators on acorns that are lying on the ground. Including, squirrels, mice, blue jays, deer and turkeys. If I plant 100 acorns,  how many of those will survive when the small seedlings emerge from the soil in the spring? Predators on the seedlings include: deer, mice, rabbits, and squirrels (they dig up the acorn). Possibly only 5% will  survive the first year (some quick math – 100 x 5% = 100 x .05 = 5 oaks).  Even if none survive to maturity, the project will not be a failure, but a success, because the land will have had someone caring for its future.

Teacher and homeschoolers

There is a Utube video called the “man who planted trees” www.youtube.com/watch?v=PYlsIZXCQa4

The book, The Man Who Planted Trees I found inspiring. I have also seen it for sale at Amazon. Also I have seen it on-line for free without the illustrations.

If you want to learn how to identify, age, and determine the height of trees get a copy of Nature Seeker Workbook at the Old Naturalist website or Amazon.com.

In addition, you can Google “planting acorns” and read about the projects that other classes have done.