Types of wood to avoid for mulch and compost

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10range

Member
Dec 9, 2010
53
Northern Indiana
I am wondering if there are particular species that should be avoided to use for mulch and compost? As I cut I have been piling branches and small limbs to run through the chipper for this purpose. At the moment I have a good pile of mulberry, black cherry and elm branches. If I recall, walnut leaves are to be avoided for compost so I assume the same would go for chips. Any other variates that are particularly good or bad?
 
I do recall a couple supposed to be bad but right now it is not coming to my feeble mind what they are.
 
Walnut is very bad for tomatoes.
 
I was told that fresh chips/sawdust should be avoided when mulching around plants as they draw nitrogen when decomposing? FWIW, I noticed a difference when using old sawdust versus fresh sawdust for mulch in my veggie garden. The older mulched veggies did seem to do better...may be because of the older mulch or perhaps that year was going to be better anyways due to different weather?
 
I don't add wood chips to compost.
They take way too long to decompose and tie up nitrogen in the process.
Why they make good mulch. weed seeds have a tough time without nitrogen.
 
Wood chips will increase acidity, so they're good for blueberries, magnolias, and so forth.

If you live in a termite area, then don't use any wood that termites will eat near your house (that leaves cedar and that's about it).
 
termites will eat cedar as soon as the oil /resin content that they don't like deteriorates.
doesn't take long with some cedar

much of the mulch that you buy has been dyed and treated - even cedar mulch.
 
Black Walnut shavings/sawdust contains juglone,a chemical that will stunt or kill surrounding vegetation of certain kinds.The nut husks also have it,plus the leaves & bark to a lesser amount.

Tomatoes shouldnt be planted within 50 ft of Walnut trees.Walnuts on the edge of corn & soybean fields will stunt the first couple rows.Rain drip from the crown/perimeter of tree will also be a problem.Bluegrass,Fescue & other grasses are fine near Walnuts.Walnut shavings/sawdust shouldnt be used for bedding horses,its reported to cause them to founder.

I've used Red/White/Bur Oak,Silver Maple,American & Red (Slippery) Elm,Black Cherry,Honey Locust,White Pine,Eastern Red Cedar/Juniper and a few other native woods for mulch -basically whatever I was cutting at the time with no ill effects on plants or garden area.I only keep Walnut to keep the weeds down in my main work area.
 
muncybob said:
I was told that fresh chips/sawdust should be avoided when mulching around plants as they draw nitrogen when decomposing? FWIW, I noticed a difference when using old sawdust versus fresh sawdust for mulch in my veggie garden. The older mulched veggies did seem to do better...may be because of the older mulch or perhaps that year was going to be better anyways due to different weather?

Bob, that is very true and that is why we always applied extra nitrogen if we spread any sawdust on the fields. We also had to put on extra lime as the sawdust tends to sour the ground a bit. We used to use some sawdust at times in the chicken coop and it worked okay. Well, when spreading the chicken manure, you have to spread that extra thin too. It is hot stuff! So it didn't work all that bad to use some sawdust but we still could notice a difference in the fields when planting corn or beans. Didn't seem to bother much with clovers though but clover doesn't need nitrogen.
 
Anything well rotted should be fine. If you have the space leave it heaped for 6 months before you apply it. Also, avoid digging it in and you substantially reduce problems with it robbing nitrogen from the soil. Effectively the sawdust is only in contact with the very top of the soil and your plants roots spread below this in the soil. Just remember that for a mulch to be effective at keeping weeds down it needs to be THICK. I have running battles with my dad over this who sprinkles an inch or so here and there and wonders why he still gets weeds.

As the sawdust rots you spread more over the top while the lowest level breaks down further.

We also use sawdust in compost toilets, the contents of which get added to our usual compost heap. Nothing gets a compost heap up to temperature like humanure; the sawdust perfectly balances the Nitrogen/Carbon balance as well as eliminating unpleasant odors. Within two weeks everything has broken down to crumbly, pleasant smelling compost. No waste as everything eventually ends up back in the garden.

http://humanurehandbook.com/

Mike
 
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