Time to germination: Several months, preferably overwintered
Time to harvest: 5 to 7 years
Light requirements: Full sun
The chestnut is a great nut tree option for those with smaller plots of land to work with. The mature trees usually stay shorter than 50 feet (many other nut trees can get over 100 feet tall). Trees do best in weather with cold winters and very warm summers. Anyone living in zones 4 to 8 can grow chestnuts, and even some lucky folks in zone 3 can get away with it if you have a sheltered location for your trees.
True chestnuts are not related to horse chestnuts or water chestnuts, so don’t be misled when shopping for seeds or seedlings. Horse chestnuts are not edible, and water chestnuts are not even nuts.
Unlike many nuts that are eaten raw, chestnuts are usually cooked in some way or another. High-tannin levels can make raw chestnuts very bitter and the uncooked shells are hard to open.
The chestnut’s shell is more leathery than hard, and will peel away from the nut meat much easier after the nuts have been cooked. Roasted chestnuts are a famous favorite, particularly during the holiday season.
Starting Your Tree
You can either start your trees by planting a simple nut, or buying seedlings
To start with a seed (which is just a chestnut itself), you will have to let it have a period of cold before it will sprout. The simplest method is to just plant your chestnuts in the fall so they can spend the winter underground, which is the natural process anyway. Large squirrel populations may make this difficult and you can find all your planted nuts have been dug up by spring.
To chill them indoors, put your seed nuts in a sealed plastic bag with some damp peat moss or sawdust. Keep them in the fridge from October until planting in the spring. Once planted, cover with a wire screen or basket to keep rodents from taking off with the seed until it is several inches high.
Seedlings should be planted in a hole dug deep enough so that the roots don’t have to be folded over to fit.
Choose a variety of tree that is resistant to chestnut blight. Disease resistance is always important when choosing any kind of plant, it is particularly important with the American chestnut. The blight swept through the United States in 1904 and killed nearly all the native chestnut trees. Get seeds or saplings from a reputable dealer and only plant those with strong resistance. Asian chestnut varieties are excellent for this.
Seedlings may be marked as “blight-free” which is not an indication of resistance. It just means the plants were grown in an area where they have not been exposed to any blight. It only ensures they are not carriers.
Hopefully you will have room for at least 2 trees, because a single chestnut tree won’t produce any nuts all by itself. Space your trees to about 40 feet apart, but not more than 100 or they won’t pollinate each other.
Your tree location should have very well-draining soil, and you might consider planting your trees on a slight slope to help with that. Trees will suffer if their roots are in soggy soil all the time.
While the tree is growing for the first year, you should water it about 10 gallons each week. Only during periods of significant drought would this be necessary once the tree is established. A feeding of standard fertilizer is a good idea every spring as well.
As already mentioned, chestnut blight is the biggest potential threat to your nut trees. Even if you’ve planted resistant varieties, you must be on the lookout for symptoms because disease resistance is not fool-proof. It’s a serious problem in the United States. It’s a fungus that attacks around the trunk of the plant, infesting the cracks or any wounds in the bark. It eventually becomes a large “canker”. Once it develops all the way around the tree, the tree will soon die. There is no treatment for it.
If blight is common in your area you will have to simply choose a different type of nut tree rather than try to fight the disease.
Insects pests are varied, with the chestnut weevil being one of the biggest problems. Adult weevils lay eggs in new nuts, and the larvae then devour the meat of the nut. As you see the nut burrs starting to develop, you can spray the tree with an insecticide like Sevin to get rid the of the weevils before they start laying eggs. Once your chestnuts have worms in them, there is nothing you can do. Watch for nuts with holes at harvest time.
A more natural approach is to lay out a white sheet under your tree, and give the branches a solid shake to knock the heavy weevils down. Collect them off the sheet and destroy. It won’t work for very large trees but it can help to keep the weevil population as a manageable level.
Harvest and Storage
Trees that you start from seeds or seedlings can take around 5 years to start growing nuts. If you start your chestnuts as grafted saplings, you may even get nuts the second year after you plant.
In the early fall, your tree will start to drop its nuts. They initially grow in a large prickly husk that looks like a big green burr (like from a burdock plant). The husk will start to dry, and split open. When you go to harvest your nuts from the ground, wear gloves to protect your hands from the spines. Some nuts will fall free of their husks, but many will still be partially encased. The husks should come off easily if they are still attached to any fallen nuts.
Because of their high starch content, chestnuts do not store as well as other nuts. You should store fresh in-the-shell chestnuts in the refrigerator for about a month or freeze them for a storage time of around 6 months. Once cooked they will only last 3 or 4 days in the fridge, but you can freeze cooked chestnuts in an airtight container for up to 9 months.
When you do cook them, you must pierce the skin or shell as least slightly or the nuts will actually explode.