Filberts / Hazelnuts after around thirty years will reach that size of 12' tall and 10 or so feet wide, every year you must cut off all the sprouts around the base of the tree , that is IF you want a tree form; other wise you will get a shrub, however there are some that wont sucker like the Turkish Tree hazelnut, the nuts are much smaller, but very tasty, I'm going to get some seed nuts of the Turkish tree nut from Burnt Ridge next year.

No, the filbert you are talking about, if left un pruned will be a large shrub with a lot of steams, it will only take the tree form with yearly pruning around the base taking all the suckers that want to make it a shrub; this is the tree/shrub with the nuts found in the market, left un pruned you will get a thicket of branches and I doubt it would get taller than 7 or 8 feet in height and could get very wide, just how wide I have no idea since no one I know grows them as a shrub, the Turkish Tree Hazelnut has much smaller nuts which is the reason I believe you won't find these nuts in the store, but will not need pruning and from what I have read can reach around 40/60 feet tall.

NJBiology:

I had three of these things about 20 years ago, the classic American Hazelnut. After five years they were 12 feet tall, and rapidly going up. Spread on each was about 10 feet. They were a big fat mess.

Hazelnuts were few and far between, and those few were tiny. If you want to plant a giant bush like this, put it in a farm field far from anything else.

I took mine out, but they were certainly "natural". So is Kudzu.

Don Yellman, Great Falls, VA

I have more positive feelings about Hazelnuts, but I grow named varieties and I can't even remember what the geneology is (American or Euro). Blight is a big problem in your area so choose non-susceptible varieties. And prepare to fight the squirrels if you want any delicious nuts!

Here in the Willamette Valley, there are many commercial orchards. The older orchards likely had American varieties and the trees there were easily 18 feet tall and were planted at least 15 feet apart. The newer orchards seem to have about 10 or 12-foot spacing.

Filberts bloom in the winter; take that into account for potential nut production.

Are those that are 18' tall grown in a tree formation, that they suckers were removed? I figure that when the suckers are removed, and the shrub is grown as a single trunk tree, it grows taller. Then again, I've seen one or two online photos that seem to demonstrate enormous specimens.

Thanks,
Steve

Orchards here have filberts trained in tree form. The ground needs as much open space as possible for mechanical harvest.

Interesting. At our old house, there was a supposed hazelnut tree in our backyard. When it was planted, it was definitely tree-like, and maybe 8' tall or so. By the time we moved, 9 years later, it was pretty tall - maybe 18' or so. I don't remember having to remove suckers to keep it in a tree form. Otoh, I never saw any nuts, either. It was from a nursery and probably a named variety - I remember the contractor mentioning that the landscaping company had given them a good deal on them to offload them, because otherwise we wouldn't have gotten such an exotic tree in our basic tree package. (They actually included 7 trees and a couple large shrubs - amazing for a new subdivision house!)

They need a pollinator.