Disposing of shavings and sawdust with yard waste

[Homer Faucett]

Joe, you're mixing apples and oranges here, and it's just not the same. Mixing sawdust into your potting media in a container is nowhere close to adding sawdust as a topdressing or mulch to a flower bed.

I can guarantee you that my 1" of sawdust on my alkaline soil cannot possibly lower the soil pH to 3.5. Your story about mixing sawdust in a garden does not have enough information to determine what exactly caused the garden to be "ruined" for two years.

I'll stand by my statement that adding native hardwood, softwood sawdust as mulch isn't a problem for plants. I also grow out hostas and other plants in large number from tissue culture for resale, and have never had a problem with it. It's a great mulch and weed barrier.

Certainly, as with all things, you have to use some common sense when you do anything. For me, it makes a lot more sense to use something in a beneficial, environmentally friendly way if possible rather than throwing it out.

Bit of background on me, I'm in the greenhouse business. Once I had 7000 geraniums go bad because the my hort supplier substituted my potting media. this occured on three benches were you could see the beginning and the end of the bad potting mix. Ph was down around 3 -3.5

Hydrangeas, Blue, Ph around 5 5.5, and top dress with AlS three times even four times a year.

We should be careful using generic terms like flowerbeds. Yes, your hostas and my hostas that set out under our trees won't be affected. In fact, two weeks ago I just dumped a bunch of red and white oak sawdust all around my Hostas. So, yes I agree with you that you won't hurt them or even some outdoor hardy ferns.

Back 25 years ago, we had a very large neighborhood garden, about 6000 sq ft on our property. The neighbor went to a sawmill and got 5or 6 pick up loads, maybe more, of sawdust and threw it on part of the garden.(He was a well-intentioned neighbor but you couldn't tell him anything, it always had to be his way) That part of the garden was ruined for two years. Finally it came back.

Do a little test with sawdust. Make a slurry of sawdust and distilled water and filter it through a paper towel, (we use filter paper, just because we do this often in the greenhouses) and then check the Ph of the water. You can get test strips from various L&G centers or pharmacy. This way you will know.

The very last thing I would add to any of my custom blended potting mixes would be sawdust. Bark chips are fine, burnt sawdust works, (Scotts Professional potting mixes Metro Mix 360 uses it) also works.

Like I mentioned I too use it on my Hostas and in my fence row to keep weeds down and that is fine.

I just get concerned when people use the term flower beds, when discussing sawdust.

Oh yea, one other thing, I don't use it anywhere close to my house. I don't need critters, insects taking up residency near my foundation.


Joe

[Joe Mioux]

Homer, I didn't say sawdust was used in my potting mix. I appologize if it appeared that way in my post.

The Ph was low and it was caused by something in the potting mix. We figure it was the peat moss coming out of a bad bog.

My main purpose of my comment was to suggest that generalized comments applying sawdust on flowerbeds may have adverse effects for some people.

As an examply, your soil is different from mine, your water quality is different from mine. Suggesting that someone just dumps sawdust down in a flower bed with out know the flowers being grown, the elements present in the soil and the Ph in the someone's garden or flowerbed could cause some problems. This is my point.

I hope this clarifies my comments

[Homer Faucett]

Joe, I think we'll just have to agree to disagree.

I want to clarify that my initial post never made any "generalized comments [about] applying sawdust on flowerbeds" that would have any likelihood of causing adverse effects for others. I use my hardwood sawdust as mulch or as browns in my compost pile, being careful not to add MDF or PT sawdust to my beds, and guess I should now add the disclaimer that this works for me, and your mileage may vary. However, in general, please note that, as I indicated earlier, soil has a large buffer capacity when compared to the relative pH and mass of mulch added. As such, wood mulch, whether in chip form or sawdust form, is unlikely to have a dramatic effect on pH when used as a mulch.

A quick review of university agricultural publications suggests that using sawdust and chips as a mulch is not detrimental to soil, and will not dramatically change the pH of the soil. In fact, one publication recognizes that "there is an old wives’ tale among some growers that 'sawdust makes the soil acid.'” This publication goes on to note that "Sawdust application to soil can cause nitrogen deficiency in plants because of the high C/N ratio of the sawdust materials. The apparent symptoms resulting from nitrogen deficiency can be mitigated with proper nitrogen and water management. The question becomes, why do growers think this is a pH effect? It is worth mentioning that, in many instances, the soils in question are acidic to start with."



While fresh sawdust will vary in pH dramatically depending upon the species of tree (test results vary from slightly basic to quite acidic), the article below sums up my basic premise most succinctly:

http://ppp.missouri.edu/meg/archives/v7n3/meg6.htm

Chris Starbuck, Woody Ornamental Horticulture, University of Missouri Columbia:

While fresh oak sawdust may have a pH as low as 3.5, I found that a 3-inch-deep layer had no measurable effect on soil pH whether used as a mulch or tilled in.

This was probably due to the relatively small amount of total acidity in the material relative to the buffering capacity of the soil. Thus, while in some cases, there may be a slight, transitory drop in pH of the soil under certain types of mulch, the evidence all seems to indicate that the long-term effect of most commonly used materials will be to increase pH.

With this information, I leave it to everyone to determine for themselves whether they would rather throw away their sawdust or use it for mulch. Everyone will have differing situations that may require alternatives, but I would urge everyone to try to find a way to dispose of sawdust that does not place it in our landfills when it can be beneficially used in so many other ways.

[Jim Becker]

Most horse people would take all the shavings/sawdust you can make. Its is becoming harder and harder to find.

True, but walnut shavings are verboten in that case...poisonous to horses.

[Joe Mioux]

I pour mine on my flower beds as free hardwood mulch.

Joe, I think we'll just have to agree to disagree.

I want to clarify that my initial post never made any "generalized comments [about] applying sawdust on flowerbeds" that would have any likelihood of causing adverse effects for others. I use my hardwood sawdust as mulch or as browns in my compost pile, being careful not to add MDF or PT sawdust to my beds, and guess .

Hi Homer,

The first OP that I quote here from you is what has caused me concern through this whole thread.

Different plants are going to react differently to mulches and the types of wood used. Moisture holding capacity, heat build-up etc.

Joe