Q.
What’s your opinion about using eucalyptus leaves as mulch?
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| Eucalyptus microtheca growing in Las Vegas |
A.
There are reports that leaves from some plants will sometimes inhibit the
growth of others. I think this is what you are referring to. This inhibition of
growth was first thought to be due to competition for water and plant nutrients,
but plant chemicals have been isolated from some fresh plants and found to
affect the growth of others. How this works depends on the plant making it and their
“allelopathy” is not consistent between different types of plants. All this
makes it difficult to isolate and prove its existence. It is clear to me that
plants “communicate” in ways we have not thought about but how this happens is
not clear.
Read more about eucalyptus leaves as a mulch here
Eucalyptus leaves as a mulch here
The classic example of this is black
walnut inhibition of growth (allelopathy) on plants growing under its canopy.
Other examples of “allelopathy” exist such as in creosote bush, lavenders, salt
cedar, bermudagrass, and others. It is not just a simple answer but varies between
allelopathic plants and plant parts. Personally, I have never tried using
eucalyptus leaves. I prefer to use wood chips as a mulch or a combination of plant parts from different plants.
One way around this is to compost, or
“rot”, eucalyptus leaves. It seems that in most cases the plant or human “toxins”
are decomposed as well rendering what’s left as nontoxic to both plants and
animals. So, for this reason, I would not use uncomposted leaves of any kind
without composting (rotting) them first unless I knew the leaves were not toxic
to other plants in the first place.