Sawing and Drying: Does the Season of the Year Matter?

      Here's a long thread that separates the science from the rumor around the question: "What's the best time of year to cut trees and dry lumber?" May 15, 2012

Question
I read that to get the finest wood for furniture grade lumber, all trees should be cut between leaf drop and the winter solstice (December 21st). Has anyone else heard this? They said that if you cut them during the rest of the year, the wood is only fit for beams and other types of construction grade lumber. They said it has to do with the sap being down and that the wood will dry much faster and with less degrade.

Forum Responses
(Sawing and Drying Forum)
From contributor D:
I have heard stories like this before but I still believe that they are total nonsense.



From contributor B:
I have harvested my own logs most any time of the year, for many years now, sawed and dried them mostly for my own use, and have never noticed any difference in the grade of lumber I ended up with. In my opinion, cutting trees at different times of the year would not change the grade of the lumber.


From contributor S:
The sap content varies very little if at all with the seasons. About the only variable you need to worry about is temperature, as some logs and lumber stain very quickly in warm weather.


From contributor E:
I cut sugar maple almost exclusively. I process it for the purpose of billiard cues. It's cut 5/4 quarter sawn. I have cut in fall, late winter, and early spring. There's most certainly a difference in the amount of sap. Cutting in late September/early October has been the least amount of sap and lightest weight (easiest to handle) logs. Winter cut was not much different, but by late February the sap begins flowing. Trees I have cut in March bled as the saw went through, and sap ran down the stump like water. Never seen a drop of sap in fall. I cut in Ohio, Wisconsin and Michigan, if that matters. Unlike more southern states, we have very distinct seasons. I know it's good cutting season when the leaves turn color. The old timers have a saying that seems very accurate. "Only cut in months that end in 'er'." I'm not a professional logger or even pro mill operator. I use my own mill and cut my own trees, so take my experience for what it's worth.


From contributor D:
I might note that I dry thousands of HM baseball bat billets. The quality and drying time never varies with the season.


From contributor M:
It would be interesting to see how the loggers could harvest all the trees in a two month period! Sawmills generally work year round and the sawyer makes decisions based on each log as to what grades can be sawn. Proper handling in the stickering and air dry process greatly affect the degrade after sawing (twist, bow, checking, splitting, staining, etc.). Dry kiln operations run on exacting schedules to properly get the upper grade lumber to a stress free 6-8% moisture content.

There are some specialty items such as sap hard maple that wholesale hardwood lumber manufacturers prefer winter sawn to minimize staining in the sapwood. It has more to do with the ability of getting the logs to the mill, sawn, stickered and in the kiln before staining can occur during the hot weather.



From contributor A:
There is a little to do with it but not what they say. The sap does not go up or down and the trees have about the same moisture the year round.

Now I spalt wood and when the trees are felled has a lot to do with how well it will spalt. Sawing in the heat of summer will cause a lot of checking and sap stain, so I try to avoid it when at all possible. Sawing in the rains of spring cause a lot of stain and mold issues.

Waiting till the leaves fall or before the bud will sure cut down on your productivity, but it sounds good in your sales pitch on why your wood is better than anyone else's.



From contributor T:
You have to hold your mouth just right, pray to the correct deity, and make sure the moon is in the correct phase. Other than that, it doesn't matter.


From contributor A:
Sawing on the dark of the moon is a good thing; just do not saw under the summer moon. (I did not mention sawing under the moon because I get too much hate mail.)


From contributor I:
I have talked with a high-end maple dealer here in Oregon and he will not accept wood cut during any time but late fall to winter, as it will be a different hue when dried, and he prefers the bluish hue of a winter sawn maple tree (big leaf maple) to the more golden hue of a summer cut tree... No word on its strength. All his words and experience, but he sells a ton of it. Also, it is best (again, according to those who do a lot of it) to cut your wood for bows during the winter as summer cut wood will likely break. Myself, I do some wood slicing and have no opinion on it yet; but I do respect the words of those I have spoken with, for what it may be worth.


From Professor Gene Wengert, forum technical advisor:
Maple is sensitive to the temperature of the log and freshly sawn lumber. The more quickly maple is logged, sawn into lumber and dried aggressively, the whiter it will be. The time involved is very short when the temperature is warm; the time is quite long during cold temperatures.

When warm, maple begins to oxidize, just like an apple turns brown after you take a bite of it. The oxidation reaction is more rapid as the temperature increases. Oxidation of maple can produce brown, pink and grayish colors.

Also, when warm, the blue stain fungus is more active.

For these reasons, people have different ideas on when to harvest maple (and other species). The strength, hardness, elasticity, machinability, glue-ability and other properties do not change with the seasons or with the moon.



From the original questioner:
Thanks again everybody! It looks as if I will cut anytime except in the hot of the summer. I have 1,000 bd ft sitting here that I cut during our heat wave. I have it covered but not in the kiln. Hopefully it won't crack too badly.


From Professor Gene Wengert, forum technical advisor:
As stated by several people already, the moisture content or sap content does not change seasonally. Certainly, there are times when the sap is flowing, but overall there is no change in the amount. Some folks think that the sap goes into the roots, but the roots are not like an underground storage tank with room for storage of liquid. The room needed to store even 10% of the moisture or sap would be very large.


From contributor V:
Basswood should be cut after the leaves are gone; stays nice and white then. If cut in the summer, get it sawed quick.


From Professor Gene Wengert, forum technical advisor:
Basswood will be whiter if cut when temperatures are cool, as the oxidation and the fungal stains proceed much slower at cool temperatures than warm temperatures. As the leaves will fall off in cooler weather, using the leaf fall as a guideline is possible, but the color has nothing to do with the leaves themselves being on or off. It is all about temperature.


From contributor N:
There has to be more liquid/sap/something flowing in during spring/summer or the leaves couldn't produce. I may be wrong, but they have a wet something in them. And also if you tap a maple tree and remove the sap, it doesn't kill the tree, so it's filling back up from somewhere and going somewhere.

Now scientifically it might not be proven, but mother nature does things scientists are confused about. And studying history, there are benefits to cutting in the cooler weather at (and we can agree with) stable sap (whether it's sitting still or in the ground, there's less of it).

And thank God he provided mother nature a way we can tell when it's cooling and the sap's not running - the leaves fall off!

Now as far as straight out cutting, it can be done any time of the year, but according to old carpenter's and sawyer's manuals, you get the best/most stable/whitest from logs cut in the fall to spring (cooler weather).

Gene, that was interesting regarding the oxidizing. I only thought that happened to paint in the sunlight. I agree we can cut at any time of the year (and I do), but with all the heat issues, it is more stable in fall/winter. I get better results from the cooler season, but I think it has more to do with the log not laying in the heat losing moisture fast, whether as a log or lumber.



From Professor Gene Wengert, forum technical advisor:
Indeed, sap moves at certain times of the year more than at other times. However, when tapping maple, the best time is likely in February before leaves are appearing.

Does anyone know how far you can suck water up against gravity? It is amazing that water can get up a tree that is higher than 30'. I have not yet seen a pump or electric wires at the base of a tree to pump water up 70' or more.

There have been many studies on sap content, especially in the pulp industry, especially since they often buy on weight. So we know that the moisture is constant and the chemistry of the sap varies little, summer to winter.

Regarding oxidation, wood is similar to an apple with a bite out of it. The apple oxidizes quickly and browns. That is what is happening with walnut sapwood darkening, discussed in another post. Sticker stain is an oxidation stain and so is non-fungal gray stain, brown stain in pine, etc. It is all about temperature and drying rate.



From contributor V:
Around here the old timers say cut basswood in the winter. I've sawn down trees in the summer and milled them 2 months later and they were getting punky and off colored at least 1 foot in on the ends and by the time they were dry, they were not nice and white. I've also sawn basswood cut in the winter 6 months later in the middle of summer, which ended up nice and white with an inch or 2 off color on the ends.


From contributor N:
Gene, as to the pumps, I read an article years ago referring to ground water and gravity (and this may relate to trees). Water in the ground to some degree has no gravitational pull. That is why you may see a spring at the top of a hill and not near the mid or lower part where you would think gravity would push it out.

I know of a waterfall in Tennessee (Virgin Falls) that is huge and is near hill top that flows out as a huge wide spring and falls approximately 175' into a hole in the ground and disappears. The huge lake nearby is still hundreds of feet in elevation below this point.

Maybe we need to study these little green things (leaves) to see whether they're sucking the liquid up or the roots are pushing the leaves out from pressure.



From contributor A:
A tree can only grow about 430 ft from its roots. But if you go up a tree that is 430 ft tall and plant a tree in the crotch of a limb it will grow up 430 ft from its roots (just saying, I know the crotch will not hold it).

You can tap a maple tree and get sap year round. But they seem to clog more when it is warm and the bugs get into your sap more. So most tap in the winter to get the purest sap. You can cut a limb off of a soft maple tree and get sweet water year round. But in the summer honeybees will show up.



From contributor Q:
Sap flows, or not, but does not empty from the wood's cells seasonally. The cells would die. They also have no mechanism to reestablish the water column up to the branches and leaves... They wouldn't be able to re-prime the works.

Pines do not lose their leaves. The waxy coating on the slender needles help prevent moisture loss to the harsh winter winds. They are growing and the sap is flowing, sometimes very slowly if at all, whenever temperatures allow, year round. Deciduous trees close up shop for the winter to avoid the winter losses but the cells must stay wet, even within the lumen.

Winter cut a thin cookie and bring it inside. Notice the color of the wood and watch as it dries. The moisture you can see are the cell lumens full of free water. As it dries this will disappear, and the color will lighten as they cross the fiber saturation point. Continue drying from this point and the cookie will shrink, distort and crack as the bound water within the cell walls evaporates as it approaches equilibrium.

Going out to cut a few trees. The hurricane low must have sucked some of the water out of those heavy beeches.



From Professor Gene Wengert, forum technical advisor:
Contributor O has some good points.

A small correction: pines and most softwoods and a few hardwoods do lose their leaves, but it is after 18 to 24 months, compared to many hardwoods and a few softwoods that keep their leaves 5 to 7 months.

Also note that the shrinkage and cracking mentioned can actually occur when the average MC is quite high. This is because the cell MC is under 30% MC or FSP. That is, some cells in the cookie will be under FSP and shrinking, etc. while others will still be above.



From contributor W:
I have been sawing and drying lumber for myself and customers for several years. The time of the year is not as important as other things. If you are not going to immediately saw and dry the lumber, paint the ends of the logs. I saw logs, put them in my de-humidification kiln, and start drying as quickly as I can. My kiln will hold 3000 B.F. and I try to do it in no more than 2 days.

It is true that warm weather can cause a staining problem, if the moisture is not removed fast enough, but at the proper rate for the species and equally for the whole load. That is why air drying does not work well and leads to more problems with the boards. 4/4 boards take a year to air dry and the ambient humidity level is usually around 16%. Wood needs to be at 8% or lower for furniture and cabinet making. The moisture level in trees varies little from one season to another, but improper handling can ruin a large portion of a good log. So cut and enjoy logs and woodworking all year long.



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