Lisa M. Rose

Acorns are very popular in my wild kitchen, and one of the recipes I make most is acorn and walnut granola. This post covers how to get acorns ready to cook, how to toast them, and how to prepare one of my favorite ways to rewild a granola recipe.

Acorns from oaks (Quercus species) are good food once the tannins are leached out; never eat them raw. Leached, dried and toasted, acorns have a flavour all their own, roasted and nutty, almost like cacao nibs. They can be used in similar ways to other nut flours, go into granola, or be baked into bread.

At a glance

Can you eat acorns?

Yes, once they are leached. Acorns are high in tannins, and a good leaching takes care of the tannic flavour. I leach mine hot: I chop the shelled nutmeats fine in a blender, simmer them at one part nuts to five parts water, and pour off and replace the water until they taste nutty, not bitter. Hot water draws out the tannins faster than a cold soak, so I can do it on the stovetop over a long weekend. Gathering, shelling and leaching are covered step by step in How to Make Acorn Flour.

Which acorns can you cook with?

Any oak’s acorns, once leached. White oaks have less tannin and give the acorn most foragers prefer, but I’m fairly indifferent: I process white and red oak acorns together. Across North America that means white oak (Quercus alba) and bur oak (Quercus macrocarpa) in the white oak group, and northern red oak (Quercus rubra) in the red oak group. In the UK the native oaks are English oak (Quercus robur) and sessile oak (Quercus petraea), and both are white oaks.

How do you toast acorns?

Toasting the leached nutmeats brings out a flavour all its own, roasted and nutty, almost like cacao nibs. Spread dried, leached nutmeats on a baking tray and toast them in the oven until they smell nutty and turn a shade darker, stirring now and then so they colour evenly.

How do you make acorn granola?

Grind leached, dried acorns into flour first, because whole or chopped dried acorns are hard enough to chip a tooth. Mix rolled oats, the acorn flour, walnuts and pumpkin seeds with cinnamon and a pinch of salt, coat them in warmed maple syrup and oil, and bake low and slow on a tray, stirring every 10 minutes until golden. Stir in dried cranberries once it comes out, and let it cool on the tray, where it crisps up. My full recipe for acorn and walnut granola, with US and metric measures, is in my weekly foraging musings on Substack: Acorn and walnut granola.

What else can you make with acorns?

The leached nutmeats can be used whole. Ground fine, acorn flour can be used in similar ways to other nut flours and added to baking mixes, though its flavour is distinct. Remember that there is no gluten in acorn flour, so plan your baking accordingly; I mix it half and half with wheat flour or a gluten-free blend. The nutmeat can also be made into a nut butter or paste with other foraged flavours like chaga, chestnut and hickory for a tasty spread. My family’s acorn banana bread is in my weekly foraging musings on Substack: My famous acorn bread.

How do you store acorns for cooking?

Fresh acorns have a short shelf life. I process them right away, or store them unshelled in cloth bags in the freezer. Once they’re leached, I dry the nutmeats fully in a warm oven or a dehydrator, then freeze them, and freeze the flour too, to prevent them from going rancid. By the end of the fall I have ten to fifteen pounds (4.5 to 7 kg) of acorn flour in my freezer.

What’s in an acorn?

An acorn is a starchy nut, starchier than a walnut or an almond. USDA figures for dried acorns give about 509 calories per 100 g (3.5 oz), with 54 g of carbohydrate, 31 g of fat and 8 g of protein, and most of the fat is monounsaturated. Those figures are for acorns before leaching. The leaching process not only extracts the tannins from the nut, but also the minerals, as Rodrigues and colleagues found in a 2026 study of three European oaks (Journal of Food Composition and Analysis, vol. 149). Leaching removed about 90 percent of the minerals and much of the fibre and sugars, while the makeup of the fat stayed much the same. I leach mine hot, in a simmering pot, and nobody has measured what is left after leaching at home, hot or cold. I cook acorns for their flavour, which is unlike any other nut. Acorns are a tree nut, so if you have a nut allergy, take care.

Sources: U.S. Department of Agriculture, Agricultural Research Service. FoodData Central: Nuts, acorns, dried (FDC ID 170565). https://fdc.nal.usda.gov/food-details/170565/nutrients Rodrigues, C. V., Maia, M. L., Babo, P. and Pintado, M. (2026). Impact of leaching on the nutritional composition of acorn species. Journal of Food Composition and Analysis, 149, 108788. https://doi.org/10.1016/j.jfca.2025.108788

Is gathering acorns bad for the oaks?

Gathering acorns will not significantly affect the growth of young oaks. Oak wilt is a concern across North America, and habitat loss is an issue for all our large hardwoods, so look after the trees you gather from.

Safety

Be certain of your identification before eating any wild plant. If in doubt, don’t forage it. Never eat acorns raw; leach them first. Acorns are a tree nut, so take care if you have a nut allergy. Gather away from roads, rail lines and lawns treated with herbicide. Some city and state parks do not allow foraging, so check the rules, and ask before you gather on land that is not yours. As with introducing any new food or herb into your diet, do so with care to rule out any adverse reaction.

Questions readers ask

Acorns in my books

I write about oaks as food and medicine in all three of my books, Midwest Foraging, Midwest Medicinal Plants and Urban Foraging (Timber Press).

Midwest Foraging by Lisa M. Rose: Amazon US or Amazon UK
Midwest Medicinal Plants by Lisa M. Rose: Amazon US or Amazon UK
Urban Foraging by Lisa M. Rose: Amazon US or Amazon UK

Recipes are part of my weekly foraging musings on Substack. Subscribe and follow to get all my tips.

Acorns are a forager’s staple. A few bags gathered before winter give you a store of nuts for soups, nut butter and flour. They take work, because fresh acorns are bitter with tannins. Leach the tannins out and the nutmeat tastes a little like chestnut.

How do you make acorn flour?

To make acorn flour, gather sound acorns from oaks (Quercus) in autumn, shell them, and leach out the bitter tannins in hot or cold water until the nutmeats taste nutty. Then dry the nutmeats fully, grind them fine in a coffee grinder, and use the flour right away or freeze it, because it goes rancid quickly.

Acorns at a glance

I’m Lisa M. Rose, author of Midwest Foraging, Midwest Medicinal Plants and Urban Foraging. This is how I turn acorns into flour.

How do you identify an oak tree?

White and red oaks (genus Quercus) are identifiable by their gray bark and alternate leaves, clustered at the terminal bud, each with soft, round edges. To discern between the two groups of oaks, white oaks have round-tipped leaves and red oaks have pointed leaves. Leaves can be deeply lobed or have no lobes at all. All acorns can have spiny or shaggy caps. Both the red and white oak produce acorns that are high in tannins, so they are not as palatable when fresh, but a good leaching can remedy the tannic flavor. White oaks have less tannin and produce the preferred acorn among foragers.

When and where do you gather acorns?

Oaks grow in parks, along streets, in yards and at the edges of woods across the Midwest, the rest of the US and the UK. Acorns fall in waves from late summer into winter. Wait for the second or third drop, usually around early October, because the first acorns to fall carry the most insect damage.

Gather away from roads, rail lines and lawns treated with herbicide. Some city and state parks do not allow foraging, so check the rules, and ask before you gather on land that is not yours.

How do you choose good acorns?

Keep acorns with a firm, clean, fresh-looking disc where the cap was attached. Throw out any with small holes, mould, or a cap that looks loose or off. Fresh acorns do not keep long. Dry them on a screen or store them somewhere cold, below 50°F (10°C), and check them for mould.

How do you shell acorns?

You can shell acorns by hand with a hammer or a pair of pliers, ideally with a good podcast on. For large batches, I’d recommend a hand-cranked nutcracker. They’re expensive, so maybe your group of forager friends could buy one together. Large pieces of nutmeat come out of the shell more easily than crushed bits, so plan your smashing with that in mind.

How do you leach the tannins out of acorns?

Next, the nutmeats need to be leached to draw out the tannins and make them good to eat. There are a few ways to do this, including a hot process and a cold process, and each one changes the final acorn flour a little.

The hot water process is the faster of the two, and you can do it on the stovetop over a long weekend. First, finely chop the nutmeats in a blender. More of the nut then touches the water, which speeds up the leaching. Simmer the chopped nutmeats in water at a ratio of one part nuts to five parts water, and keep replacing the water until the nutmeats taste nutty, not bitter. White oak acorns carry less tannin than red oak acorns, so they need less time.

The cold water process takes longer, usually several days. Soak the nutmeats in cold water and change the water once or twice a day until the bitterness is gone. It’s slower, but cold-leached nutmeats make a flour that holds together better in baking.

How do you dry, grind and store acorn flour?

Dry the leached nutmeats fully in a low oven or a dehydrator. Grind them fine in a coffee grinder. Use the flour right away or freeze it, because acorn flour goes rancid quickly at room temperature.

How do you cook with acorn flour?

Acorn flour has no gluten, so I mix it half and half with wheat flour or a gluten-free blend. Toasting the leached nutmeats brings out a roasted flavor, and acorns can stand in for chestnuts in most recipes. My famous acorn bread comes out on Sunday in my weekly foraging musings on Substack.

For the other fruit and nuts dropping in town this month, see Wild Fruit and Nuts in the City.

Questions readers ask

Safety

Be certain of your identification before eating any wild plant. If in doubt, don’t forage it. Never eat acorns raw; leach them first. As with introducing any new food or herb into your diet, do so with care to rule out any adverse reaction.

Acorns in my books

Oaks and acorns are in Midwest Foraging (page 184) and Urban Foraging.

Midwest Foraging by Lisa M. Rose: Amazon US or Amazon UK
Midwest Medicinal Plants by Lisa M. Rose: Amazon US or Amazon UK
Urban Foraging by Lisa M. Rose: Amazon US or Amazon UK

Recipes are part of my weekly foraging musings on Substack. Subscribe and follow to get all my tips.

You don’t need the woods to forage. In October, apples, pears and crab apples hang over garden walls and park paths, oaks and chestnuts drop their nuts on city lawns, and rose hips redden in the hedges. These six grow in towns across the US and the UK.

What wild fruit and nuts can you forage in a city in October?

In October you can forage apples, crab apples, wild pears, rose hips, acorns and sweet chestnuts in towns and cities across the US and the UK. Gather away from polluted ground, pick fruit that has fallen or comes away easily from the branch, and leave horse chestnuts alone, because they are inedible.

City fruit and nuts at a glance

I’m Lisa M. Rose, author of Midwest Foraging, Midwest Medicinal Plants and Urban Foraging, and these are the six I look for in town each October.

Before you gather

As a city-dwelling forager, I take soil contamination seriously. Land in towns and cities can hold lead, arsenic and other pollutants that plants take up, so learn the history of a site before you gather there. Avoid old industrial lots, railway lines, old gas station sites and busy roads, and skip lawns, golf courses and easements that may be sprayed. If you are unfamiliar with the soil’s history, find a different place to gather. If in doubt, don’t gather, and ask a trusted resource for help with identification or the local rules.

I cover this in more depth in my foraging guides. In the US? Check out Midwest Foraging (Amazon US, Amazon UK). Outside the US or in the city? Take a look at Urban Foraging (Amazon US, Amazon UK).

1. Apples (Malus species)

Look for apple trees in old gardens, at the edges of parks, in vacant lots and in former orchards. A once-domesticated, now-wild apple tastes sweet, tannic and astringent all at once, with more range than the few varieties in the supermarket. Apples that come away easily from the branch, and fresh windfalls, are the ripest, so wait until close to frost and pass over fruit with insect damage.

2. Crab apples (Malus species)

Crab apples grow in park plantings, along streets and in hedgerows. The crab apple is a small wild apple, under 2 inches (5 cm) across, with all the good qualities of its larger cousin and more tartness. Wait for the fruit to soften and gather it after the first frost, when it is noticeably sweeter, then use it by equal weight in any recipe that calls for apples.

3. Wild pears (Pyrus species)

Wild pears grow on old trees left behind from former gardens and orchards. Wild pears taste like a cultivated Bartlett but are smaller, rounder and firmer. Gather pears that have fallen or come away easily from the branch, and keep them in a paper bag in the fridge for up to two weeks, or slice and freeze them.

4. Rose hips (Rosa species)

Rose hips ripen in park hedges, on planted shrub roses and along coastal paths. After the rose is pollinated it sets its fruit, the hip, which turns deep red after the first hard frost. The hips are high in vitamin C, and fresh or dried they go into cordials, jelly and syrup.

5. Acorns (Quercus species)

Acorns fall from oaks along streets and in parks. Red and white oaks both drop acorns high in tannins, but a good leaching takes the bitterness out, and white oaks carry less tannin to begin with. Once leached, the nutmeat tastes much like chestnut and can go into soup, nut butter and flour for baking. The full method is in How to Make Acorn Flour.

6. Chestnuts (Castanea species) and the lookalike to leave alone

Sweet chestnuts grow in parks and on old estates. A chestnut is close to a complete food, full of protein, minerals and carbohydrate, with a mild flavour that suits bread, soup and roasting over a fire. A ripe bur comes away easily and holds two or three shiny, chocolate-brown nuts, and the harvest lasts only about two weeks.

Horse chestnut, a common street and park tree, is inedible. Its husks carry a few short spikes and hold one round, glossy nut with no point, and its leaves are divided into five to seven leaflets like a hand. If in doubt, leave it.

Questions readers ask

Safety

Be certain of your identification before eating any wild plant. If in doubt, don’t forage it. As with introducing any new food or herb into your diet, do so with care to rule out any adverse reaction.

Books by Lisa M. Rose

Midwest Foraging by Lisa M. Rose: Amazon US or Amazon UK
Midwest Medicinal Plants by Lisa M. Rose: Amazon US or Amazon UK
Urban Foraging by Lisa M. Rose: Amazon US or Amazon UK

Recipes are part of my weekly foraging musings on Substack. Subscribe and follow to get all my tips.