Growing a tree from a seed is an incredibly fulfilling experience. Not only is it somewhat miraculous watching a seed come alive, but it goes on to grow far beyond the human scale and live for decades if not centuries. There are many trees you can and should grow, but if you have no idea where to start then you may as well try an oak. Oaks are keystone species and are extremely beneficial to the environment, providing food and shelter for hundreds of insects, birds, mammals and even other plants and fungus. Given their widespread distribution on Turtle Island, you likely have an oak species already adapted to your area. Today I will guide you through the basics of growing an oak tree, which will more or less teach you how to grow other trees and thus get you started on what will likely become your life's most important work.
All species of oak belong to the genus Quercus, but broadly speaking there are two main groups of oak tree we need to be familiar with: white oaks and red oaks. You can generally tell these groups apart by whether or not their leaves have smooth, rounded lobes (white oaks) or bristled, spiky lobes (red oaks). White oak acorns will also be oblong while red oak acorns are more or less round. White oak acorns have the least amount of tannins, making them much more palatable and less bitter than red oak acorns. For this reason, white oak acorns can be difficult to find because they are so quickly devoured by wildlife, so you should feel a sense of triumph if you ever find a fresh one.
The best time to collect an acorn is from late September into October, as the acorns are falling to the ground (though they can be collected directly from the tree's branches). Fresh acorns range from green to dark brown once fully ripe (often a mottling of the two), and the telltale sign that an acorn is ready to harvest is that its cap removes easily from the nut. Tan acorns are dried out and should be ignored. You'll also want to be sure that the acorns you collect are free of damage or small holes, which are a sign that an oak weevil larva is inside munching away on the nutmeat.
The timing and situation of each tree can vary. While most trees will produce some acorns every year, a high yield year will occur about every 2-3 years for red oaks and 4-6 years for white oaks in what are known as mast years. If you get into the habit of seed collecting, you will be diligently looking for viable acorns at every moment. Check many trees in your area over many weeks and collect what you can while leaving some for the squirrels and blue jays. After collecting, you can check your acorns for viability by placing them in a bucket of water. Floaters should be removed and sinkers can be left in for up to 48 hours to maximize moisture content and aid in their germination process.
Ideally, you probably want to put your acorns in the ground soon after collecting them, as acorns are prone to both drying out and getting moldy. If there is going to be a lag time between when you collect and when you plant, I recommend putting your acorns in an unsealed plastic bag and keeping them in the fridge. The plastic bag will help hold in the moisture, but you want to leave it somewhat open so there can be a bit of gas exchange and a release of excess moisture.
White oaks acorns will begin to germinate soon after they drop, so you can expect to have sapling already growing before winter arrives. Red oak acorns need to be cold stratified, or chilled for several months between 34-41°F, before they will germinate. In most places, this will mean sowing in the fall and letting this process occur naturally over the winter, but if you live in a place with mild winters, you can keep your acorns in a moist bag of sand in your fridge for 2-3 months and plant them in the spring.
To sow your acorn, just place it on its side about one inch deep into your potting mix. The composition of your mix is up to you, it just needs to hold some amount of moisture but still drain well. You can put your acorns directly in the ground or plant them in individual containers about 2-4" deep to allow space for a taproot to develop. Planting in containers is nice because you can move your set-up around easily if needed, but make sure they are still staying cold and moist for the stratification period. You can also cluster acorns together in case some don't germinate and thin out or transfer any that survive.
On top of all this, remember to protect your acorns from squirrels, blue jays, grackles and more, who will almost certainly scavenge these nuts if they can manage it (and they almost certainly will). This can mostly be mitigated by covering your growing area with 1/4" hardware cloth and securing it well with weights or staples. Squirrels can easily chew through mesh and reach through chicken wire, so learn from my mistakes and go for the heavy-duty option.
If all your careful planning worked out, the acorns will sprout and send out a shoot over a period of several weeks. The first couple of years of your trees' lives will be the most critical, requiring consistent watering, plenty of sunlight and continued protection from wildlife. The big question now is where will you plant your oaks. If you have space in your yard, go for it, but also consider doing a little guerilla gardening. If you put your tree in a park or some other manicured area, someone might actually take care of it for you without realizing it. You could also find an abandoned landscape in need of some life and tend to it personally. Of course, you can also always give your trees away or try to sell them.
To aid in the tree's long term survival, make sure your tree has lots of mulch and that weeds and grasses are kept away. Give your tree a ring of mulch about 2 feet in diameter with a slight depression just around the base where the water will collect. Larger trees need to be watered slowly over long periods in order for the water to properly penetrate to the roots. Adding a watering bag around the base of your tree can all help keep the tree hydrated if no one is around to water it. Tying your tree to a couple of stakes will help stabilize it, and adding some mesh netting around the tree can keep animals from gnawing the bark.
This guide was an attempt at summarizing everything I've come to learn about growing an oak from an acorn, and I've had to leave out various details to make it more succinct. If you want to dive deep and learn more about growing trees, I highly recommend you check out the Woody Plant Seed Manual which is a comprehensive resource for collecting seeds and growing woody things. I hope that these tips encourage you to grow your own tree or at least allow you to see oaks in a different light.
