Myth alert!

Juniper mulch is just great to use as a mulch. Not to worry.

Why does your friend think wood chips from Junipers is toxic? Some Cedars do have a resistance to being digested by the soil bacteria (rot resistance) but I have not seen anything to suggest that chipped Juniper wood is a plant growth suppressant, and where I have used Juniper wood chips I have not seen any problem with plant growth.

Junipers are a funny lot.

The essential oils of juniper can vary quite a bit. Some are edible, some are not, some are allelopathic, some are not. I think Texas juniper is Juniperus deppeana or mexicana and I can't say to what extent it's allelopathic, but, according to the National Forest Service, it along with the Rocky Mountain Juniper (J. scopulorum) and the Utah Juniper (J. osteosperma) have shown to be allelopathic to certain shrubs and grasses. Your Texas Juniper is a suspect in the lack of pine reforestation (see link).

tj

Here is a link that might be useful: Search on allelopathy

Just found out Texas Cedar is Juniperus ashei. Ah, common names. It, too, has allelopathic qualities, mainly in the camphor. I wouldn't use it.

tj

Here is a link that might be useful: Texas Cedar allelopathy

As Rhizo says, I wouldn't worry about it:-) A great many different trees are allelopathic to some extent - far more than most juniper species - and they are still used as garden mulches with no ill-effect. Eucalyptus is one that comes to mind, as are pines. With the exception of Juglans or walnuts, the allelopathy tends to be rather specific and at its worst, simply has a tendency to increase weed suppression. And that's not a bad thing when it comes to mulch!!

You can use the juniper mulch without worry.

Here is a link that might be useful: the myth of allelopathic wood mulches

I do not see any reference specific to Juniperus ashei (nor any juniper, for that matter) in the Chalker-Scott article. Only Thuja and the true cedars. It certainly might be ok or only affect grasses but I'd still use caution. Also, the fact that it has been there a year means you may be out of the woods, so to speak. Time will tell, I guess.

tj

Actually, as I think about it, your best bet is to talk to your county extention office. I'm sure they have more experience with this specific juniper than any of us. They would have the best info.

tj

It's pretty simple to do a Google search on 'juniper mulch', 'Texas cedar mulch' or 'cedar mulch' that will turn up various references to the suitablilty of various junipers - including J. ashei - for mulching purposes. Junipers are used very commonly throughout Texas and various parts of the Southwest for mulching, simply because they are so plentiful, are often considered weed trees, and because other types of hardwood mulches are not available or too costly.

From the Colorado extension office's mulch handout:
The other issue, and probably the more relevant question, is what plant is actually referred to as "cedar". In Colorado, we have very few true cedars (the genus of true cedar is Cedrus). What most people call "red cedar" is either a juniper (i.e., Eastern Red Cedar, Juniperus virginiana) or arborvitae, Thuja spp. (i.e., Western Red Cedar). Neither of these have toxic qualities for young plants when used as a mulch.

Most "cedar" mulch in Colorado (unless they are bagged and shipped from another part of the country) will not be the true cedar. They will most likely be either the juniper or arborvitae, which are not toxic when used as mulch.

Heck, they even make mulches out of eucalyptus, walnuts and pecans and these all have far stronger allelopathic properties than do junipers.

Chalker-Scott doesn't address it because a) juniper mulch is not common in her area (PNW) and b) it is just not a problem.

And for a very specific Texas reference, follow the link.

Here is a link that might be useful: Ashe juniper ('cedar') mulch

Gardengal is right. I use "cedar" mulch exclusively for the reasons she suggested, namely it is a pest plant (so I'm doing someone a favor), and it is plentiful. It makes great mulch. I get it at Lowe's.

There are people here with tractor/bulldozer attachments that can "eat" a cedar tree to the ground in a few seconds and mulch it in another minute or so. Once the tree is cut off to the ground, it will not come back. Then the grass will grow in the area. I can't find the video but there is another machine that shreds the tree from the top down in just a few seconds.