"paghat" wrote in message
news
In article , Hans L
wrote:

We have a small area next to the house (in the Cleveland, Ohio, region),
where my wife has planted petunias for the second year in a row. It
gets
sun part of the day. Last year, the flowers lourished and eventually
covered the entire surface. However, before they had proliferated, one
could see the hardened, dreary-looking soil. So this year, I added
mulch.
Looks great.

Now, the flowers did not expand at all this year, and a bush in this
area
died rather quickly at the beginning of the summer. A neighbor and my
wife
claim that it is the mulch that hampered the growth, and my question is
if
this could be the case. It needs to be mentioned that we have had a lot
of
rain this year, that there is no slope in this area, that the
humus/soil-cover is rather thin, and that there is clay underneath.

Thanks -- Hans L

If you used something like heavy straw for winter mulch, it has to be
removed near winter's end or early spring as it smothers stuff that is
trying to grow, & as straw too-slowly decays, it robs the surface soil of
nitrogen. In some cases, an uncomposted bark can also rob the soil of
nitrogen.

But if you used a completely composted manure topcoating for mulch, that
improves the soil & healthful microorganism populations, in addition to
protecting roots of things in winter & encouraging worms to work the soil
a bit. Manure compost would not have stunted or stopped the growth of
anything except seedlings (a pure surface compost tends to be sterile & it
is difficult for seedlings to get started through it, which is why compost
topcoatings suppresses weeds, but not so good if seeds were surface-sown).


I'd look elsewhere for the cause of problems. Unturned compacted soil with
too little organic material in it, plus poorly draining clay soil during
a period of heavy rainfall, would predictably stunt plant growth or even
kill some of things outright.

This is entirely correct, however I would also add that the specific type of
mulch can make an impact on the plants' performance. Mulches comprised
primarily of sawdust or very fine bark can reduce the available nitrogen in
the top layer of the soil, which can result in stunted or or less than
optimal growth. This is more likely to be a problem with very shallow rooted
and herbaceous plants like annuals and most perennials rather than larger
and sturdier, woody shrubs and trees with deeper root penetration. Simply
providing additional nitrogen rich fertilizer will offset this or use a
compost mulch in these areas.

Since you indicate a shrub has died off as well, I'd be more inclined to
agree with paggers that too much rainwater combined with the less than ideal
drainage of heavy clay soil is most likely the culprit. This can be a fatal
combination for the majority of plants.

pam - gardengal