The End of Chestnuts? No!

Blight Strikes

I looked up into the tree that I had planted 20 years ago and saw what I had long feared: two major limbs with sparse, undersized leaves. Blight had finally got a toehold on the Colossal chestnut tree, which, for the past 15 years, has supplied us with all the chestnuts we could eat. (“Colossal” is the variety name, apt for the size of the chestnuts it produces.)Chestnuts falling free from burrMy first inclination, before even identifying chestnut blight as the culprit, was to lop off the two limbs. Once I got up close and personal with the tree, the tell-tale orange areas within cracks in the bark stared me in the face.Blight on chestnut barkThere is no cure for chestnut blight. Removing infected wood does remove a source of inoculum to limit its spread. In Europe, the disease has been limited by hypovirulence, a virus (CHV1) that attacks the blight fungus. Some success has been achieved using a naturally occurring virus found on blighted trees in Michigan.

There is some evidence, although not confirmed with rigorous scientific testing, that mud packs made from soil taken from the base of a tree, can slow or halt spread of the disease. The mud packs need to be applied to each disease canker and then held in place with shrink wrap, or painted or sprayed on, followed by a layer of latex paint. Not an easy job as you move higher and higher up into the tree.

Pruned Colossal tree

Colossal, post surgery


Chestnut species vary in their response to the blight fungus. American chestnut (Castanea dentata) is very susceptible; the fungus arrived here from Asia in the early 1900s, and within a half a century had killed billions of trees. European chestnut (C. sativa) was also susceptible, but was protected by the naturally spreading fungal virus.

Chinese chestnut (C.mollisima) and Japanese chestnut (C. crenata) both have some resistance — but not immunity — to the disease, and have contributed their genes to resistant varieties. Collosal, in fact, is a hybrid of European and Japanese chestnuts, and it has some resistance to blight. But, evidently, not enough. I am hoping that the previously extremely wet season contributed to the evidence of symptoms, and that some drier seasons will keep the tree alive longer.

I’m not planning to sit back and let my chestnut-eating days shrink away to nothing. For starters, keeping my tree vigorous with pruning and good fertility might keep small cracks, into which new infections could enter, from developing. Also, chestnut trees need cross-pollination, so I do have other varieties planted. Also planted 20 years ago was Marigoule, also yielding fairly large nuts. Some sources say “blight susceptible,” others saw “blight resistant;” my large tree shows no signs or symptoms of blight. Yet.

This spring I planted two more European x Japanese chestnut hybrids. I shouldn’t have felt so confident that MY trees wouldn’t get blighted. Precoce Migoule and Marsol, the two varieties I planted, are, like Marigoule, allegedly “blight resistant,” or not.

Generally, the Chinese varieties and their hybrids are the most blight resistance. And I have two of those, actually one tree on which I grafted two different varieties. Qing is pure Chinese with easy-to-peel nuts having excellent flavor. Peach, the other variety, is also pure Chinese, though the nuts are ho-hum in flavor. Both varieties have borne for me for a number of years, yet the nuts never seem ripe once they drop.

One More Thing . . .

Is your head spinning yet? One more wrinkle in this chestnut saga. It turns out that if a pure or hybrid Chinese variety pollinates a pure or hybrid Japanese variety, the latter gets dark staining of the nuts, with a loss in quality. So I was phasing out (with a chainsaw) some other Chinese varieties I had planted. Now, with blight lurking in the wings, I’m having second thoughts.

Enough negativity about chestnuts. On the positive side, Chestnut trees’ shiny, green leaves are attractive and turn a rich golden yellow color in fall. The nuts are tasty and nutritious. With their high starch and low fat content, they’ve been called “the bread tree.” Gluten-free bread tree, for those who care about gluten. 

So, do plant chestnuts. Two different varieties for cross-pollination. If I was planting again — and I might — I’d seek out trees from among Qing, Benton Harbor, Everfresh, Gideon, and Mossberger. Or, for Japanese varieties and their hybrids: Maraval, Marigoule, Labor Day, Precoce Migoule, and Marsol.

Colossal, at 10 years old

Colossal, at 10 years old

Colossal, in autumn, 12years old

Colossal, in autumn, 12 years old


Nuts Galore

    What a nutty time of year, literally! Chestnuts and black walnuts, two of my favorite nuts, were raining down, figuratively, just before the middle of the month.
    Black walnuts are free for the taking. Wild trees are everywhere around here, and keep increasing because of overlooked nuts buried by squirrels. The nuts are so abundant this year, and most years, that squirrels and humans can have their fill. (Not so with my filbert nuts; squirrels will strip those bushes clean.)
    Black walnuts have a strong flavor. Like dark beer, fresh blackcurrants, and okra, not everyone likes the flavor. That’s fine. Fast food chains might purvey foods that everyone sort of likes, while a home gardener and gatherer can grow and gather fruits and vegetable and nuts that he or she really, really likes, and ignore what he or she really, really does not like.
    There’s also, if you’re not a squirrel, the getting-to-the-nut problem with black walnuts. The first step is to remove it, as soon as possible after gathering the soft, messy, dark-staining husk. My wife, Deb, does this; I try and come up with contraptions to ease the job of husking 10 five-gallon buckets worth of nuts that eventually transmutes to 8 one-quart mason jars filled with nutmeats.
    We’ve gone through a few incarnations of huskers. One year I bought an old fashioned corn husker, which needed some modification with an angle grinder. It didn’t do the job. Another year I ran the tractor back and forth over the nuts in the driveway, a common method, but not effective enough.Various black walnut hullers
    In years past, Deb has given each nut a tap with a light sledge hammer, which is enough to loosen the husk so it can be easily twisted off. Another year, I mounted a flat piece of metal in a slot I cut in a short length of 2-by-4 wood. Rolling the nut over the metal edge was enough to make the husk easy to twist off.
    This year I drilled a nut-sized hole in a piece of wood and mounted it over a bucket. One whack with a light sledge hammer drove the nut through, minus the husk. Or, it was supposed to do that. One piece of husk, on the leading edge, alway stayed attached to the nut.
    So now Deb is back to one of the standard methods for de-husking black walnuts: Stomp on them with your heel, then pick them off to rub off any remaining husk.

Readying for Cold Weather

    Enough with the nuts . . .  tonight (October 10th) temperatures are predicted to be in the low 30s, which means the high 20s in this cold spot. Mostly, I and the garden are ready for cold. Still to be done are:
    •Close all hose spigots and open ends of drip emitters and main lines, watering wands, and hose sprayers to prevent the expansion of freezing water water from causing damage;row covered vegetables
    •Set up hoops and either clear plastic or row covers over beds of lettuce, Chinese cabbage, endive, arugula, and mustard greens. These vegetables tolerate temperatures well into the 20s, but I’ll cover them just in case. And they’ll anyway need the protective coverings soon;Row covered vegetables
    •Bring tropical plants indoors. Banana “trees,” staghorn fern, avocado, and clivia have laughed off cold so far, but tomorrow morning would not look so cheery if left outdoors. They get bright windows. A banana’s growing point is below ground which allows some gardeners to merely lop the whole top off the plant and store the bulb, in its pot, through winter under cool, dark conditions;Tropical plants indoors
    •Subtropical plants could survive temperatures into the 20s. I’m hoping for a crop from Golden Nugget mandarin, Meyer lemon, and Meiwa kumquat, so they’ve been walked indoors and perched near the most sun-washed windows in my house.
    •Feijoa, olive, and Chilean guava are, like citrus, evergreen, subtropical plants, except they can tolerate colder temperatures than citrus. They sport neither fruits, flowers, nor flower buds now, so will remain outdoors until temperatures dip into the low 20s. Potted rosemary is also in this category; because I will be visiting it many times over the months that follow to clip off sprigs clipped for pizza and salad dressing, it’s new home is a sunny kitchen window.
    •Basil will be dead tomorrow. Leafy stems picked today, their bottoms plunked into a glass of water, will provide fresh basil for a few weeks. Then it’s on to frozen basil pesto.

Cold Weather Takes a Rain Check, Without the Rain

    The Morning After: No drama. That’s the way I like it. The slider on my min-max thermometer registered a low of 29° last night. A far cry from my first gardens, in Wisconsin, where it seemed every year (for the five I gardened there) around September 21st I would be wake to a frigid morning and a garden of blackened tomato, marigold, and pepper plants. This morning, marigolds and peppers have felt the chill, but live on to die slowly day by day as the sun dips lower in the sky and temperatures creep lower and lower.


American Chestnuts, Gone but not Dead

The chestnuts are big and fat and tasty — obviously not American chestnuts. I harvest so many chestnuts, also big and fat, each year from my Colossal variety trees that I never bothered to look beneath my Marigoule trees. Marigoule is planted further from my house than Colossal.

Marigoule chestnuts

Marigoule chestnuts

    American chestnuts, Castanea dentata, are small but very tasty, or so I have read and heard. I’ve never tasted one. The trees were devastated by a blight throughout the early 20th century. Previous to blight, the trees were so numerous in our eastern forests that it was said that a squirrel leaping from one chestnut branch to another could travel from Maine to Georgia without touching the ground.
    Something like 40 billion trees died to the ground. But roots survive, sprouting new shoots each year to provide a host to keep the blight fungus alive. Trees might even grow to have trunks a half-foot or more in diameter before the fungus strikes to cut the tree to the ground again.

A Tale of Blight, Pollination, and Staining

    Various chestnut species inhabit different parts of the world. Most blight resistant are Chinese chestnut (C. mollisima) and Japanese chestnut (C. crenata), where the blight originated. European chestnuts (C. sativa) is susceptible to blight, so has been mated with the Chinese or Japanese species to yield resistant, tasty hybrids. My Colossal and Marigoule trees are hybrids of the European and Japanese species.
    But the plot thickens. Colossal, though a hybrid, is only slightly resistant to blight. My tree, over 15 years old, exhibits no sign yet, but I’m keeping an eye out for telltale orange pustules on its bark, limb dieback, and massive resprouting below points of infection. (It is only more recently that Colossal was determined to be more susceptible than originally thought.)

Chinese chesstnut seedling

Chinese chesstnut seedling

   Marigoule is quite resistant to blight. The tree also has an elegant, upright form, more like that of American chestnuts.
    So what’s the problem? If blight were to eventually strike Colossal dead, I could just walk a little further and gather Marigould nuts from the ground. Except that any chestnut tree needs cross-pollination from another variety in order to bear nuts.
    When I planted Colossal and Marigoule, I also planted some other chestnut trees, blight resistant Chinese chestnuts: a seedling and the varieties Peach and Eaton, the latter of which also has Japanese and American chestnuts in its parentage. All these yield good-tasting nuts, though not nearly as large and easy to peel as Colossal and Marigould, all are blight resistant, and any of them could pollinate Marigoule. Problem solved? Not quite.
    The plot thickens further. The nuts of Colossal, Marigoule, and other Japanese and Japanese hybrid chestnuts sometimes get a black staining that ruins their quality. Not all the nuts, just some of them. Recent research pins the blame not on yet another disease, but on pollen from Chinese or Chinese hybrid chestnut trees.

Nutty Present and Futures

    Going forward, I’m keeping a close eye on Colossal. If Colossal gets sick, one option that, so far, has been effective only in Michigan, might be to infect the blighted trees with a blight fungus that has been weakened because of infection with a virus. The weakened fungus is less deadly.
    Or, I could cut down Colossal and Marigoule, and feast only on the Chinese chestnuts and their hybrids. But Colossal and Marigoule are both so productive and produce such large, tasty, easy to peel nuts.
    I could cut down the Chinese seedlings and hybrids to prevent their pollination and staining of Colossal and Marigoule nuts. Except I’ve recently discovered that my Marigoule must have been pollinated by one of my Chinese trees because Colossal is pollen sterile. Marigoule can pollinate Colossal, but not vice versa. So to get nuts on Marigoule without Chinese chestnut pollen, I’d need another Japanese chestnut or hybrid, either a whole new tree or a branch grafted on either Colossal or Marigoule.. The variety Labor Day (also known as J60) yields good nuts and is blight resistant.
    I’ll probably take the “wait and see” option. After all, there’s no sign of blight on any trees; few nuts get staining; and we gather more than enough nuts for roasting and stews.



Popcorn & Chestnuts, Bigger is Better But Not Always

   Orville Redenbacker’s popcorn may be an “exclusive kernel hybrid that pops up lighter and fluffier than ordinary popcorn,” but my popcorn — nonhybrids whose seeds I’ve saved for many years — tastes better. I grow two varieties, Pink Pearl and Pennsylvania Dutch Butter Flavored Popcorn.
    This winter my popcorns’ poppability was especially poor, probably because of the weather. Really! Popcorn pops when the small amount of water within each kernel, heated above the boiling point, builds up enough pressure to explode the kernel, turning it inside out. For good popping, a kernel needs an intact hull and moisture within. Not just any amount of moisture, though, but as close as possible to 13.5%.
    (Other whole grains, such as wheat berries and rice, don’t pop with the same explosive force as popcorn because their hulls are porous.)Popcorn hanging from rafters for winter
    My popcorn spends winter, as ears, hanging from the kitchen rafters. I suspect the kernels are too dry because colder winter weather results in drier air indoors. Cold air holds less moisture than warm air so the colder the outdoor temperatures, the drier the air, once it is warmed.
    The kernels need moisture, but not more than 13.5%. Fortunately, for us popcorn lovers, back in 1950 a Mr. Stephen Dexter of Lansing, Michigan came up with an easy way to get the moisture just right, as spelled out in U.S. patent number 2497399. And for those of us who want to start eating our home-grown popcorn early in the season, when kernels may be too moist, his method also sucks excess moisture out of the kernels to bring the level down to 13.5%. Watch out Orville!
    Now for the method . . .  to quote, “I have discovered that popcorn can be maintained at the best popping condition or restored to that condition by storing it in a closed container in which the atmosphere is maintained at approximately 75% Popcorn being treated to pop betterrelative humidity. This relative humidity can be maintained throughout a wide range of temperatures by placing in the container a saturated solution of common table salt.” So the first step is to create a saturated solution of salt; I dissolved as much salt as possible (about 1.5 ounces) in a half a cup of water, and then added a little more to make sure that it was saturated.
    It’s important that the popcorn kernels don’t make contact with the salt solution. Mr Dexter maintained the right atmosphere by putting blotting paper soaked in the solution in a sealed container with the kernels. I put the kernels into a Mason jar and then set a beaker with the solution on top of the kernels.

A Little Science, A Lot Better Poppability

    Not to doubt Mr. Dexter or the patent process, but the scientist in me had to test the method. A handful of shucked kernels went into each of two Mason jars. One jar was left open to the atmosphere. The other was sealed after I set the beaker of salt solution atop the kernels. Poppability tests came 3 days later. Pennsylvania Dutch Butter Flavored Popcorn, which normally pops pretty well, popped to 1/3 greater volume after the moisture treatment. Pink Pearl awaits testing.

Positive results of popcorn treatment

Positive results of popcorn treatment

    At their best, neither would compare in volume increase with Orville Redenbacher’s popcorn, which claims a 44:1 increase. My popcorn costs nothing except my time (pleasantly spent) and is an organically grown, wholesome, whole grain that hangs decoratively from my kitchen rafter and tastes better. Let Orville have his fluff.

Editing my Chestnut Planting

    On to another grain, chestnuts, called the “grain that grows on trees” because, unlike other nuts, it’s low in fat and protein but high in starch. My trees demand little more from me than daily harvest during their two-week ripening period. I have 4 trees but harvest all the nuts I need from one tree, aptly named Colossal for the truly colossal size of the nuts it yield.
    Colossal, a hybrid of Castanea sativa (European chestnut) and C. crenata (Japanese chestnut), has its Achilles heel. Make that Achilles heels, plural. The first is that it is susceptible to the chestnut blight that decimated chestnut trees from

My majestic seedling Chinese chestnut

My majestic seedling Chinese chestnut

Maine to Georgia in the 20th century. Colossal is probably not quite as susceptible to blight as are American chestnuts; my trees, knock on (chestnut) wood, are 17 years old and have never had blight.
    More serious is IKB, internal kernel breakdown, which turns the kernels dark and ruins their flavor. IKB occurs in a certain percentage of nuts of European x Japanese varieties when they are pollinated by a Chinese chestnut (C. mollissima) or hybrid. And vice versa. Most of my other trees are Chinese or Chinese hybrids.
 Sprouting chestnut   I was going to plant some of my Colossal nuts to make more suitable pollinators for Colossal but, as chestnut researcher Dr. Dennis Fulbright of MSU pointed out to me, those seedlings would have some Chinese “blood” in them. Too bad; I wintered the nuts in a baggie with moist potting soil in my unheated basement. Those nuts now believe that winter is over, and are already sprouting roots.
    I’ll grit my teeth and put the chainsaw to my beautiful, large Chinese and Chinese hybrid chestnuts, and rely on my one, smaller Marigoule chestnut, a European x Japanese hybrid, to offer pollen to Colossal. Marigoule is blight susceptible, so I’m looking to plant another European x Japanese hybrid called Labor Day, which is blight resistant.

Filbert catkins

Filbert catkins

    At any rate, coming on the heels of winter, it’s nice to see something growing, even if it’s nothing more than a 2 inch root sprout that pushed its way out of a chestnut. Oh, and outside, filbert branches are now draped with catkins, chains of male flowers. And fuzzy, gray catkins have puffed out (indoors, on branches in a vase) on contorted stems of fantail pussy willow. And an abundance of tender green seedling are sprouting in the greenhouse. Happy spring!

Rice, Corn, & Barley Harvest

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It’s been awhile since the grains have been harvested so it’s time to prepare them for consumption. Longest in preparation will be barley.

The barley is from last year’s harvest, and the grain-laden stalks have been bundled together and hanging from a kitchen rafter since then. I’ve procrastinated processing because of last year’s frustrations in trying to thresh wheat, also grown last year; the grains clung tenaciously to their stalks and no amount of battering would thoroughly separate them. I’ve also procrastinated because the bundle of barley’s tawny brown stems, with long, delicate, spiky awns emerging from the heads, look so decorative dangling upside down near the kitchen ceiling.

A bare spot now remains where the barley once hung. Earlier today, after being stuffed into a pillowcase and batted against a brick wall, the stalks easily released their plump grains. I separated the grain rom the chaff by pouring the grains back and forth between two buckets in a slight breeze, and soon had the whole crop cleaned.
As you’ve probably guessed by now, my barley crop wasn’t measured in tons or even bushels. I had planted a 3 foot by 3 foot area and reaped a quarter of a pound. Consulting my 1914 “Farmer’s Cyclopedia of Agriculture,” an acre of barley (back then and in Iowa) averaged 45 bushels of barley, or 1,800 pounds, which would translate to a bit over one-third of a pound for my 9 square foot plot. Respectable for my first try.
The end-product for my crop will be beer. More specifically, the goal was to find out how much barley to grow to make a 6-pack. My next step, then, is to malt the barley. More on that at a later date . . .
I “hauled in” the rice harvest back in early October, all 40 grams of it. That 40 grams was not a bad yield considering that I got the seedlings started late; that I only planted a 2 foot by 3 foot bed of it; that it was growing under dryland conditions, which yields less than wetland rice; and the variety I planted, Hayayuki, is a wetland variety. Still, it was fun.
The aforementioned limitations are nothing compared to the limitation in preparing the rice for consumption. Like most other grains, rice has a hull that needs to be removed before the grain can be eaten. (The hull is no impediment with barley for malting because what’s used for beer is maltose-laden water that is leached through the sprouted, cracked grain.) Hullers are available for small-scale grain processing, but are neither economical nor capable of handling nano-yields such as my 40 grams.
A conversation with Ben Falk (, who had given me the seeds and has harvested over 100 pounds of rice in Vermont, did not leave me optimistic about getting off those hulls. (He has a small huller.) No need for me to try cracking them off with a rolling pin, boiling them and hoping they would float up to be skimmed off, or toasting — he’d already tried all that.
Years ago, I got a Solis coffee grinder that does an adjustable grind. How about setting the Solis to barely grind the rice, just enough to crack off the hulls? The problem is that the largest setting was a bit too small for the rice grains. Still, no other options presented themselves. What I now have is cracked rice. I cooked some; the flavor was very bland, even for rice.
It isn’t only a lot more growing experience that is responsible for my much more successful crop of a third grain: corn. Corn is easier to grow, to harvest, and to process than other grains on a home garden scale. I grow popcorn and polenta corn in addition to, of course, sweet corn, the latter considered a vegetable because it’s eaten “green,” that is, before full maturity.
It’s with good reason that corn has been such a success for so long here in the Americas. The grains are large, they come packed together in a single ear, and that ear is covered by one easily shucked husk. Corn is such a successful cultivated grain that it can’t even survive in the wild. An ear dropped to the ground would sprout too many seedlings so close together that they would be stunted fighting each other for water, light, and nutrients.
Processing popcorn and polenta corn entails nothing more than picking it, pulling back the husk, and hanging it from kitchen rafters until ready for use. Giving a ear an “indian burn” snaps off kernels for popping or grinding.
One more home-grown grain rounds out my larder. Chestnuts. They’re not actually a grain but are a uniquely starchy nut so fulfill much the same purpose as any grain in the diet. Chestnuts have the advantages of being perennial, borne on an attractive tree, and, because they bloom late and have few pests, bearing reliably.
Chestnut preparation is easy: One cut crosswise about half way through each nut, then roasting in a hot oven for about 30 minutes. Delicious.
Colossal chestnut


“Cure” is a funny sort of word. It means, on the one hand, to relieve from illness, and, on the other hand, to subject to some sort of preservative process. (And, on yet another hand, a few other things.)
The chestnut variety ‘Colossal’
Which brings me to my chestnuts . . .  no, they’re not diseased, but they do need to be cured. We chestnut growers face two opposing goals with our harvested nuts: Good storage versus good eating. A freshly fallen chestnut is rich in starch and moisture and, because it is alive, it’s able to fight off mold and store well if kept near freezing temperatures. But it doesn’t taste good. For best eating, the nuts need to cure, a process whereby some moisture is lost and some of the starch changes to sugars, dramatically improving flavor. But cured nuts don’t keep well.
This story has one other wrinkle, the chestnut weevil. This bugger lays eggs in the nuts while they’re on the tree and, after nuts drop, eats some nutmeat and then crawls into the ground for winter. 
Chestnuts begin to lose moisture usually as soon as they touch ground. They start at about 50% moisture and once moisture drops below 35%, they’re dead and will rot unless eaten quickly or thoroughly dried (for chestnut flour, for instance). The way to store chestnuts, then, is to make sure they’re plumped up with water, and the way to do this is with a dunk in water for about a week. Soaking also kills weevils. The nuts may begin to ferment, so the flavor is ruined after the dunking — but they’re not supposed to be eaten yet. 
Another way to deal with hydration and weevils is with a 30 minute dunk in water heated to 120° F. The temperature and timing are exacting so I this week opted for the less exacting week-long soaking from my just-harvested nuts.
Kept plump with moisture and at temperatures near freezing, nuts subjected to either water treatment will store well until — since they are alive — they begin to sprout.
The way to get chestnuts ready for eating is to bring them to a drier and slightly warmer, but still cool, location. Depending on temperature and humidity, the transformation from foul to flavorful could take from 3 to 14 days. Cooler temperatures and moister air lengthen the curing time, but also offer better flavored chestnuts.
(Much of this information was gleaned from an article by Greg Miller in The Chestnut Grower, Greg is the owner of the Empire Chestnut Company,, which sells high-quality chestnuts, chestnut trees, and chestnut seeds.)
The sweet potato harvest is in, as it should be before cold threatens. Soil temperatures below 50° F. cause chilling injury to the roots and internal decay. As I’ve written previously, I planted the vines atop piles of wood chips and leaves that arborists and landscapers dump here and that I spread as mulch later in autumn. All summer, the sweet potatoe vines multiplied and stretched out as far as 20 feet from my original plants. 
Unfortunately, it looks like the plants put more energy into making vines than fat roots. From 4 plants and a lot of vine growth I harvested a mere half-bushel of sweet potatoes. A couple of the potatoes were football-sized, others were below average, and too many were like swollen, orange strings. 
Stringy roots result from too rich a soil, but I didn’t even plant in soil! Probably the hot summer and sometime moist weather sped decomposition of the chips and leaves to release nutrients.
But we’re here to talk about curing. Like chestnuts, sweet potatoes need to be cured for good storage and good flavor. In this case, what’s needed are a week and a half of temperatures 80 to 85° F. and high humidity, not easy to find this time of year. My greenhouse benches are cleared and temperatures there  get quite warm on sunny days, so that’s were I’ve spread out the sweet potatoes. Longer curing times are needed at cooler temperatures, such as at room temperature. Covering potatoes with cloth or putting them in perforated plastic bags, or keeping them in the greenhouse, maintains high humidity.
Once cured, sweet potatoes are ready for eating. My paltry crop will be eaten soon, but for longer storage, medium humidity and temperature around 60° F. are ideal. Refrigeration is a no-no. The roots get chilled, just as they would in the ground (or my mulch pile), and show it. 
Black walnuts trees abound and the nuts are raining down and free for the taking. The sooner the fleshy husk is taken off, the less stained and better-flavored the nuts. No end of innovative ways have been devised for separating the husk from the shell, everything from spreading the harvested nuts on the driveway and running over them with your car to stomping on each nut to cutting the husks off to letting the weight of a small sledge loosen them and then twisting them off with gloved hand. We opt mostly for the latter, followed by hosing and drying them in the sun for a couple of days.
Of course, hulled black walnuts are not yet ready to crack and eat; they need to be cured, for a couple of months. Curing black walnuts is simple, involving nothing more than storage in any cool or cold, dry location impervious to squirrels. There are plenty of black walnuts for human and squirrels alike, but a cache of hulled, clean nuts is too tempting to those rats with tails.