THE WHITE WALNUT
BY AKIVA SILVER
Butternuts, the white walnut! I have heard many people say that they hate black walnut trees (this is a total mystery to me), but I have never heard anyone complain of a butternut. When grown in an open yard, they are beautiful spreading trees that have a tropical feel. They produce one of the most pleasant shades and their nuts are delicious. Sadly, butternuts are quietly disappearing from our woods. It has become quite difficult to find healthy butternuts in the forest canopy. Some estimates are that over 90% of them are gone. Still, every fall I gather, plant, and eat butternuts with my kids. I hope that this article can help you to enjoy these beloved trees.
Butternut (juglans cinera) is a fast growing tree closely related to and resembling Eastern black walnut (juglans nigra). The two trees can often be found growing together in rich flood plains as well as on the thinner soil of the hillsides. Butternut, aka white walnut, is a sun loving tree that grows rapidly. Several feet of growth is often seen from seedlings every year. The leaves are big, over a foot long. They are composed of many leaflets, often 9, with a large terminal leaflet. There are two easy ways to tell a butternut from a black walnut. The first is the nuts of black walnuts are round, while butternuts are more barrel shaped. The second is the bark. Black walnuts have a dark brown deeply furrowed bark at maturity, while butternuts have a smooth, whitish grey colored bark. The buds and leaf scars are worth checking out. The leaf scars look like strange monkey faces (almost everyone seems to agree on this).
Butternuts are dying from a disease called butternut canker, or if you like really tough scientific names, sirococcus clavigignenti-juglandacearum. It is a fungus that kills the trees by consuming the cambium layer. Lots of dead branches in the crown is a pretty decent indicator of the disease, along with swollen, cracked cankers. The logs rot very slowly and I often find them laying across the ground with their bark falling off. The bark is grey colored on top, but jet black underneath. The black inner bark is usually wet and slimy. That slimy black inner bark from dead butternut trees makes an excellent dye.
It is hard to paint a picture of what it feels like to be under a butternut tree. There really is nothing like it. Tree lovers who have walked in groves of Eastern hemlock can appreciate the uniqueness of feeling that certain species inspire. The butternut is one such species.
Today we can find pure butternuts scattered about in the woods slowly dying. We also find them as hybrids along city streets and in yards and parks. In the early 1900’s Japanese walnuts (juglans ailanthifolia) was widely planted as a garden tree. The trees are short (40 ft.), and are often wider than tall. Japanese walnuts produce tasty nuts with some varieties that crack out very easily. For whatever reason, butternuts readily accept pollen from Japanese walnuts. The resulting hybrids are so common that almost all butternuts near residential areas are hybrids. Healthy, disease resistant hybrids are the norm.
It is very difficult to tell the difference between a true butternut and a hybrid. There are numerous things to look at, but genetic testing is considered the only valid method by many. To me, it doesn’t matter that much. I am really just looking at the ecological functions of the trees, not their genes. I’m sure many in the scientific community would shudder at my attitude about this. That is okay. I just want to grow lots of trees and eat lots of nuts. I am more concerned with their ability to grow big and healthy and to produce copious amounts of nuts. I am not a purist, but if you are, there are numerous people working to save butternut trees. Foresters and laypeople collect seed from pure jugulans cinera every year to further the species. A quick internet search will reveal many such projects. I collect seed from every butternut type tree I can.
Butternuts are well named. They taste like mild walnuts with a slight butteryness. They ripen much earlier than many people expect, so are often scooped up by squirrels. I collect butternuts beginning at the end of August some years, with most of the crop ripening in September. The nuts are in sticky green husks, that stain just like black walnuts do. They are so big and in such large amounts that it usually takes only a few minutes to fill a 5 gallon bucket.
A mature tree grown in the open sun can produce unbelievable amounts of nuts in a good year. I have filled entire pickup trucks more than once from a single tree in a single season. It is so much fun to harvest butternuts, that its hard to stop. I like to crawl around on my hands and knees with as I drag a bucket or tub with me. Moving more than a few feet at a time is almost impossible because the ground can be a pure carpet of nuts.
After I collect the nuts, I start processing them right away. If you just let them sit in their husks for weeks, the husks will leach into the nut. This ruins the mild flavor of butternuts, they will taste more like black walnuts (which are good too, but not mild).
You can set the nuts out to dry on some cardboard or paper in a well ventilated space safe from rodents (good luck!). You can also remove the husks while they are green. I throw buckets of them in metal bins with some water, and sometimes with gravel too. Using a paint mixer, I vigorously stir them until the husks are removed. I then set them on a wire screen and spray with a hose. They will look remarkably clean and beautiful after this treatment.
They should be well dried before storing. I store them in large onion sacks to keep good air flow. If they are moist during storage, mold can be expected. Kept dry in their shells, butternuts will be good to eat for decades.
Cracking them is similar to black walnuts. The two options I see are specialized nut crackers or a hammer. If you want to get an excellent cracker, the ‘master nut cracker’ is the best. It works smoothly with a lever action. My 3 year old son has no trouble cracking black walnuts and butternuts with our master nut cracker. If you’re using a hammer, then hold the butternut upright and hit it on the top. It will usually split lengthwise and you can pick out the nutmeat with a nut pick.
The nut meats are great raw, in oatmeal, toasted, or in baked goods.
Butternuts are really easy to grow from seed. They need to be kept moist and cold during the winter, and they have to not be eaten by rodents. I achieve these conditions by burying my seed in buckets. The buckets are under ground to their full depth so that the lid of the bucket is even with the ground. I drill holes in the bottom and top of the bucket to allow rain and melting snow to pass through. I mix the butternuts with sand in the bucket. Snap the lid tight and cover with a layer of mulch. In the spring, the nuts can be planted out as soon as the ground thaws.
They can be direct seeded at their permanent location or grown in a nursery. For direct seeding beware of squirrels that will pull up sprouted nuts. You may have to place a guard around the nut. If growing the seeds out in a nursery, you have 3 options. One option is to plant them into beds and dig them up after a growing season. This works fine so long as you have a deep enough soil to be able to easily dig up the tap rooted seedling. A second option is to raise them in pots. This is the worst option as you will have a tree with a circling root system most likely. You will also be stuck watering all summer.
The third option is my new favorite. I plant butternuts into air pruned beds. These are raised beds that are suspended above the ground. The bottom of the bed is a sheet of galvanized hardware cloth. As the butternuts grow, they develop a tap root. When this tap root reaches through the hardware cloth, the tip dies. The response of the tree is remarkable. The entire length of the tap root bushes out. Numerous fibrous side roots develop in all directions. Trees grown this way transplant very well and are quite thick and strong after a single growing season. Of course, nothing compares to the root system of a direct seeded tree.
I hope that you will join my efforts to add more butternuts and their hybrids to the world. The trees are beautiful, long lived, exceptional for wildlife, they are great for climbing, and produce excellent nuts. Along with oaks, chestnuts, black walnuts, and hickory nuts, butternuts are one of the key components of a diverse and healthy nut forest.