Ask the Arborist

Great oaks from little acorns

Apparently many of you have been visiting our beautiful parks lately because I’ve been hearing a lot about all of the acorns dropping from the majestic oak trees. Every year about this time I’m asked if there’s a secret to successfully planting acorns.

If you don’t have any on hand, finish reading this article, then drive straight over to a park with oak trees. You’ll find thousands of acorns about to drop or already on the ground ready for collection.

Acorns that are good for planting are mostly brown in color. If you can find them still hanging on the tree, grab ’em. They will pop out of their caps and right into your hands.

If you wait too long, any acorns lying on the ground may be invaded by insects or eaten by squirrels, deer, birds and even dogs.

To select the best acorns for germination, place those gathered into a container of cool water and let them soak for about 24 hours. After that time the good acorns will be lying on the bottom of the container and the bad ones will be floating on top.

Not every good acorn germinates, so for best results plant several acorns in several pots and not directly in the ground. You can use a pot of any size or shape to start your acorns, but make sure it has good drainage.

Fill the pot with planting mix or peat moss to within 2 or 3 inches from the top and pack lightly. Then place the acorn on its side and cover it with an inch of planter mix, again packing lightly.

It is tempting to just push the acorn into the ground pointed end first, but that will inhibit the new shoot from easily popping its head out of the soil, so make sure it’s lying on its side. Water it well the first time, then just keep the soil moist. In less than three weeks a small shoot will emerge.

Eventually the pointed end of the acorn will crack open and the first thing that comes out is a tap root that goes straight down. Soon after the root comes out a small shoot will appear above the soil surface with one little leaf.

As the days go by and the shoot gets taller, it will begin to take on the shape of a tree with more leaves unfolding from day to day.

Sometimes, as the root pushes down into the pot it will cause the still attached acorn to pop up above the soil surface. If this happens, do not try to pull the acorn off the shoot because the small tree still needs it for nutrition.

If you have your planting containers outside, you will have to protect them from birds and especially squirrels, which have a knack for finding acorns even when planted.

A good way to protect them is to cover the pots with chicken wire or something similar that inhibits the critters from getting to the acorn but allows enough room for the new shoot to expand.

You can also start your new oak tree in a pot inside your house. Just make sure that you place it in a sunny window where you can watch its progress every day. It’s really cool to see that first little bulge in the earth as the shoot struggles its way into the sunlight.

One month after the shoot emerges, give your little trees some liquid plant fertilizer when you water them.

Just dilute a few drops in a cup of water per tree and apply it every three or four weeks.

You will be amazed at how fast the little trees grow with proper care. Wait until the container is packed with good roots before you try to transplant your new little tree in a bigger pot. If you are eventually going to plant the tree in your garden or yard, wait until it is about 3 feet high and the little trunk is nice and sturdy.

Many valley oaks live at least 300 years, and I have seen some make it past 600.

If you planted a small valley oak this year in a location where it had a chance to grow unmolested, that tree could still be living in the year 2613. Imagine that.

So what are you waiting for?

Plant some acorns and perhaps you will create a monument that will still be standing 600 years from now.

David D. Mortimer is a certifi ed arborist and a certified tree risk assessor with more than 35 years’ experience in the treecare industry. Email questions to

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