Species such as maple and walnut dry at an intermediate rate, ie a 1” walnut board air dried in the south in the summer time will dry in about 120 days, and species such as oak, mesquite, and hickory dry very slowly (ie 1” per year). It is best to store lumber “in the tree” until you are ready to mill it.
The nuts need to cure for 2-3 weeks before using, so leave them somewhere with good air circulation that's protected from moisture, and stir them around once a day or so, if you happen to think about it.
From contributor S: 2" walnut will air dry without problems, just don't dry it too fast. Sure there are a lot of variables, but it's not like grey elm that warps or hard maple that will stain or white oak that will check. So I'll stand by my statement that walnut is relatively easy to dry.
Eventually, the wood will reach a moisture content that is in equilibrium with the surrounding ambient air and humidity. While a 1-inch red oak board may take two to three months to air-dry, a 2-inch board may take six to eight months, and even thicker lumber may take years.
Let the slabs air-dry until the wood is dried to less than 20% moisture content. This will take some time (years) so be patient. Once the wood moisture content is below 20% it can be slowly dried in a kiln to something around 10 or 11%. It is now safe to work the wood into a table top.
For 4/4, oftentimes it is well air dried within 60 days; 8/4 in about 180 days of good weather. Air drying longer than needed can increase checking, warp, discoloration, etc. In fact, get air dried lumber into a shed to prevent these losses, as rain and sun cause loss.
Black Walnuts will stay fresh in the refrigerator for about 1 year, and in the freezer, you can expect freshness to maintain for over a year.
Place the walnuts above a furnace or radiator, or any place with air circulation that will reach a temperature of at least 95 degrees. Ideally, the nuts should not be in a temperature above 105 degrees. Drying time in this temperature range will take about three to four days.
As far as drying them goes, I recommend stripping the bark off, sealing the ends with a good quality log sealer, and letting them set as long as possible (maybe 3-4 years if possible) under cover and in open air circulation.
It is generally best to mill a log as soon as possible after cutting it. Sealing the end grain is the right thing to do but just as important is where the log lies.
How to tell when black walnuts are ready to harvest: When the husk is brown, is cracked, gives in to pressure, or peels away easily from the nut inside. Walnuts that are still green on the outside are okay to pick, but require more work to get to the nut meat.
Rot Resistance: Black Walnut is rated as very durable in terms of decay resistance, though it is susceptible to insect attack. Workability: Typically easy to work provided the grain is straight and regular. Planer tearout can sometimes be a problem when surfacing pieces with irregular or figured grain.
Even a single black walnut is worth a lot of money, given that the species grows enormous. You can care for the one growing in your backyard and sell it for a lot of money if it grows massive and is a perfect high-quality tree without blemishes.
Storage. Once your walnuts have had plenty of time to cure, you can store them as-is in a cool, dark place for up to a year (though they may turn rancid before then). Your best bet, however, is to shell the nuts and freeze them. If you do this, they'll last indefinitely.
Prevention and treatment. Perhaps the most important thing to keep in mind is to always wear gloves when you're handling black walnuts. Disposable gloves are the best, obviously, because you can then just toss them and not worry about getting any juglone on anything else.
Black walnuts have a yellow-green husk that turns dark brown as it ages. The best time to harvest these black walnuts is from late September to October for most of the United States.
Logs. It is advisable to mill logs as soon as possible after the tree has been felled. If this is not possible and the log is going to sit for a while then you should coat the end of the log (both ends) with a sealer to slow the drying process down.
If you plan to use certain boards first, place them near the top of the stack for easier access. Stack the lumber in neat layers as soon after sawing as possible. Leave a 1- or 2-inch space between boards within a layer. Wood strips, called “stickers,” provide the space between layers to allow air movement.
Generally, it's far, far better to rough-mill while green, dry in a stack with stickers to allow airflow and if necessary considerable weight to put on the stack, then do final shaping with the moisture content near the desired environment. First, it's much faster to dry the relatively thin rough boards.
Drying Lumber
Once you've cut your logs, it's time to exercise patience. The rule of thumb for air-drying lumber is one year of drying for each inch of board thickness. Buy a moisture meter so you can check your lumber's moisture content. Kiln-dried lumber is dried to about seven percent moisture content.
Drying by kiln is more expensive than natural air drying, as it requires a special chamber and energy source. The process can be less gentle on the wood, resulting in more cracks, splits, and warps.
-Overly dry lumber is more brittle and so machines more poorly with chipped grain being much more common. Planer or roller splits are also more likely. Machine knives dull more rapidly because the wood fibers require more effort to cut.