Bob Bauer wrote:
Shiva said:
Roland ...wrote:
I am not alone in thinking that clay is good. Let me provide the opinion
of several Rose authorities:
snips IMPRESSIVE list of other people who love clay
Very nice. I still disagree.

I too disagree. And here are some of my arguments:

First and biggest: most clay minerals cause a chemical reaction
that 'locks up' iron in the soil. That is, it makes it unavailable
for plant use. Regular amendments of iron are needed for good plant
health in these soils. New growth appearing on the rose bush that is
light yellow green or whitish is an indication of lack of iron.

It isn't really clay that locks up nutrient - or more accurately,
inhibits their availability for absorption. It's soil pH. It is true
that unless soil pH is balanced, nutrient become unavailable
chemically. Here's a partial explanation on one of my favorite rose
sites: http://www.scvrs.homestead.com/BalancePH.html

Second: Clay soils are usually alkaline with a pH of 7 or above.
Roses thrive in a slightly acid soil of pH 6.5. Therefore acid
inducing is necessary. This is usually accomplished in these soils
with the addition of decomposing plant material such as compost or
horse manure or even top mulch.

I thought the pH of clay soils varies widely regionally. In the SE,
they say clay is acidic. In the west, they say clay is alkaline. In
fact, people with clay soils in the SE add lime to keep it from being
too acidic.

Third: High percentage clay soils have poor drainage. In areas with
a lot of rain, this leads to occasional standing water, something that
quickly becomes deadly for rose roots, and at the least leads to poor
root health.

Drainage is definitely important. If you live on a slope, it's a lot
less of a concern with roses than with some plants that hate wet roots.
Drains are the easiest thing to build: they are simply a channel on the
low side of the hole,about 4 inches wide and almost as deep as the
hole, filled with rocks. Amendment addresses drainage and pH. Around
here, you can kill more roses during 6 months of assured seasonal
drought than you can by drowning them during the 6 months of
intermittent rain. But if you live in flat clay, you need to create
drainage, and raised beds will do it for you. Replacing clay with top
soil will only create a pot and can actually create a drain into your
rose hole.

Fourth: Clay soils are dense and easily compacted which keeps air
from moving down into the soil. This slows the natural process of
composting of whatever organic matter is present in the soil. People
with heavy clay soils need to dig with a digging fork and aerate the
soil around their roses in order for them to perform well. Or add a
lot of worms..... grin

Flip side of Number 3. Call it 3.b. This ignores the possibility of
soil organisms working in the top 6 inches of soil if they are provided
a lot of organic matter. That's where most of the roots are anyway, top
8 inches for sure. A few anchor roots go down deep, but I find them
drilled right into the clay. But compaction is a real issue in all
garden soils: they shouldn't be compressed when wet, and they shouldn't
be trampled.

In summary: All of these problems can be dealt with, but it takes
extra effort than that required for loamy soil with a high (60
percent) level of decomposing organic matter.

Well, yeah. We all want loamy soil. I'm not convinced you get it all
that often in a bag. Some are good, some really stink, in my
experience. I amend clay with potting soil, especially when the other
component of the hole is rocks.

It is possible to grow good roses in high percentage clay soils, but
you have to amend on a regular basis.

Absolutely true. You reap what you so. Ashes to ashes, dust to dust.
You have to return to the soils what you take out.

Since most people don't know
this or do it, they would tend to see roses grown in these soils
perform less well than roses grown in 'better' soils.

Or they learn a not very hard lesson: mulch mulch mulch.

My soil is a river floodplain in the bottom of an old lake bed, and
therefore very high in clay. In order to grow roses well in my soil,
I dig a hole about 20 inches in diameter and 20 inches deep, toss the
clay, and fill the hole with 2 cubic feet of 'EarthGro' brand Potting
Soil bought from Home Depot for $3.96 a bag.

Since I started doing this, my roses have thrived. Roses still
growing in my older beds with high percentage clay soils do noticeably
less well even though the soil around these plants is top amended
regularly.

And this has nothing to do with more experience or perhaps a tendency
early on to cut corner, hmmm? Every rose I plugged into a cheaty little
hole thumbed its nose at me, except for Iceberg, which promptly grew to
7 feet.

When you look at the big picture of how much you really spend on each
rose bush, an extra 4 bucks is really worth the value that it gives
in the long run.

True. $4 of material is a necessity for every rose hole. Next time I
dig a rose hole in pure yaller clay, I'm going to take a picture for
you: both the clay and the rose. I just make loam in situ.

By the way, I learned the above technique from an assortment of great
and impressive Rose Authorities as well, right here on rgr several
years ago.

The voice of experience...... heh heh

What roses have you killed lately, anyway? I never hear about yer roses
dying. Fess up.
;~)