Harvesting Acorn

Preparing Acorn
Written By Manzanita Cooperative

This article was adapted with permission from content created by Mighty Wild and updated to include insights from Manzanita Cooperative operations in California.

Step 1: Collecting Acorns

What types of oaks produce acorns?

All oaks bear acorns, and all those acorns are edible. White oaks tend to have lower tannis, making them easier to process. They also have lower fat content and higher starch. But, just like wine grapes, people have strong opinions about their acorn of choice and many people prefer the nuts of various red oak species and even tan oak - which is not a true oak but does produce an acorn.

If you’re interested in identifying different oaks, this field guide distinguishes the North American species.

How do you collect acorns on site?

The key is watching the trees for when the acorns are dropping. The first drop of acorns is usually not the best since the tree will naturally drop the weevil infested acorns first. In most of California, the first drop happens in late August. Wait until September to avoid these first low-quality nuts.

Acorn harvesting can be done either by harvesting unripe green nuts from the trees or by waiting for ripe nuts to fall. Nuts harvested green will take 6-8 weeks to fully ripen. For most home harvesters though, picking up ripe nuts from the ground will be the easiest method.

The easiest collection spots are flat grassy areas. These locations can be mowed before the acorn drop. Typically, there will be lots of sticks under these trees, which should be gathered beforehand to have a clean field. You can use a bag-a-nut to pick up the acorns in order to save yourself from bending over with a bucket. Alternatively, if you are only needing to gather a few pounds, the nut wizard or the stab-a-nut works well.  Whatever you choose, it is critical to sanitize your equipment before and after collection in order to prevent spreading tree diseases such as oak wilt or sudden death. 

Cold will prompt the nuts to ripen and if you wait 2-3 days after the first cold snap of the year, you’ll often find the ground covered. Spreading a tarp immediately after the frost to catch these nuts can be a good way to simplify your harvest. Lacking a cold snap, a stick or pole can bring down the nuts onto your tarp easily enough. You’ll need to do some sorting to remove the sticks and leaves, but even so a single person working alone can harvest 200 pounds of acorn a day easily enough. People working in teams can easily gather more.

Where can you source acorns and how much does it cost?

If you don’t have acorns of your own, you can likely find someone who does and doesn’t want them easily enough by asking people in your community via your social network of choice. Harvesting from stands of oaks on the road or in public parks is not recommended since you don’t know what chemicals may have been sprayed.

Harvesting on publicly owned land may be legal where you are, the Forest service has a relatively straightforward permitting process if so - but make sure you’re not interfering with any traditional tribal harvests. It is important to note that California Tribes have diverse territorial and cultural gathering protocols. Local tribes should be consulted to align gathering practices with traditional ecological knowledge and cultural practices specific to place.

You may also be able to negotiate with large ranchers and timber stand owners to collect on their land for a fixed fee per pound.

Acorns are an important food for many animals who rely on them to build up fat reserves they will rely on through the winter. Even so, millions of tons of acorn rot unharvested and uneaten in California every year. We recommend taking no more than 1/3 of the nuts from any given site to make sure there is no negative impact.

If you intend to harvest at a larger scale, there is an ethical obligation to actively monitor the impact of harvests on wildlife. Manzanita Cooperative uses rigorous scientific monitoring including cameras, bioacoustics, and soil sampling to ensure their operations are truly sustainable and we recommend that other producers do the same.

How many acorns fall from a tree?

Oaks exhibit masting behaviors. This means that the oaks store up their energy and alternate between periods of high acorn production (called mast) and lower acorn production.  According to Ian Pearse “masting is the intermittent and synchronized production of seeds.”

In practice this means that the same tree may produce hundreds of pounds one year and almost nothing another. Many other plants like pecans and walnuts follow this rhythm, and it is believed to have evolved over time as a defense mechanism.

Depending on the species, some Californian Oak species like the Valley Oak can drop as much as 2,000 pounds on a mast year. Different species seem to mast at different times, so in a healthy mixed oak forest, there will be something available to harvest most years.

Further reading:

Manzanita Cooperative https://manzanitacooperative.com
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Acorn Haggis