Regional Gardening Reports :: National Gardening Association

In the Garden:
November, 2003
Regional Report

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Clockwise from top: a rotten black walnut hull, a nut, a cracked and empty nutshell. Hey squirrel, bring that back!

Seasonal Fare

Most of us don't keep nuts as an essential pantry staple, but when we look back to old timey fall harvest and Thanksgiving meals, the dishes often included nuts. Nuts were a significant source of nutrition, free for the gathering and easy to store for the coming winter. In the mid-Atlantic region, the menu could easily have included black walnuts.

A Noteworthy Native
Black walnut (Juglans nigra) is native to a wide region -- from Massachusetts to Florida to Texas to Minnesota. On rich, moist, bottomland soil this tree grows big, easily spreading 50 to 75 feet high and wide or even twice that size. Historically, this huge hardwood was made into fine furniture, cabinetry, and gun stocks; burled walnut veneer is naturally exquisite.

This tree is a tap-rooted survivor, tolerating heat, cold, drought, and adverse conditions. Its canopy is sparse enough for grass to grow beneath it, but the fall color is usually poor, and some years the leaves drop by early fall. Garden variety phenology says the black walnut leafs out after the last spring frost, indicating it's tomato planting time. In ornamental terms, this means its coarse, thick branches may stay bare for a long time.

Gourmet Delight
The trees drop their green fruits each fall. When you clean up the mess, the now blackening, rotting hulls stain your hands and shoes and clothes with a nearly indelible, natural, black-brown dye.

Black walnuts are edible and have a unique flavor, stronger than ordinary walnuts. They are uncommon in the kitchen, however, because once hulled, the remaining shell is so incredibly hard that it takes a hammer or a vise to crack it. The trick is not to mash the shell fragments into the nutmeat or else you will be seeing the dentist.

Landscapers Take Care
Last but not least, as you may have heard, these amazing trees are toxic to some plants. Many plants are sensitive to the allelopathic chemical, juglone, contained primarily in its roots as well as (to some extent) in its leaves, stems, fruits, and so on. Azaleas, rhododendrons, and other related plants are especially sensitive to juglone, as are tomatoes and their relatives.

Sometimes I think plant failures are attributed to the juglone when the real culprit is competition; black walnut is a big tree stealing nutrients, water, and sunlight. Grass grows well beneath these trees though, as do hostas and vinca minor, liriope, and my beloved daffodils. If you have one of these trees, be a little bit cautious when adding new plants nearby, and remember the grand scale this tree will reach.

You Be the Judge
To me, black walnut has a certain regal air of dark and heavy grandeur about it year-round, yet to some people it might seem the perfect complement to a haunted house. Either way, common sense says these trees are just too big for most home landscapes. So although a black walnut tree is a notable native tree, it is not necessarily the right tree for every yard. But don't feel bad. If your neighbor has one, I'm sure they'd share some nuts for your harvest feast if you ask nicely, and are willing to do the prep work yourself.

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