The bright red and bright yellow, orange, black, white, variegated,
striped or blotched barrel cacti (most commonly Gymnocalycium
mihanovichii) have no chlorophyll production of their own and HAVE to be
grafted onto a green cactus to live parasitically. The host is usuall
Hylocereus trigonus.

The variegated (such as the streaked multicolored 'Hibotan Nishiki') and
the black cultivars do produce some of their own chlorophyll and can be
babied to survive without a host, but it's harder. For variegated
cultivars, the more green in the mix the more likely they are to survive
without a host cacti, whereas the ones with almost no green streaking will
be hardest to grow separate from a host; they all grow better as grafts.
There's a "half and half" cultivar (of Obregonia denegrii) completely
green on one side, completely yellow on the other, and it seems to grow
pretty "evenly" as the green side disperses chlorophyl to the entire
barrel. Such as these are usually not really growing on their own roots
but are root-grafts onto a sturdier cacti so as not to be so delicate, yet
with no host plant above the roots.

Virtually all these cultivars remain pretty small. The ones that grow
slowest tend to become the hardiest, and those which have a sudden growth
spurt or produce lots of baby barrels around the sides too quickly do less
well.

Newly obtained chlorophyl-free grafted cacti can initially be delicate
compared to a cactus that feeds itself with sunlight, and it's essential
that the green cactus under it never end up in shade as it has to feed
itself and the colorful graft. Some production growers attempt to
minimalize the size of the host so that the cactus almost looks like it
has no host, but these are more apt to have the chlorophyl-provider become
overshadowed in time, and the graft will thrive until its host is no
longer getting sunlight.

When they survive, the red or yellow or other colorful top will outgrow
its host, and produce many little barrels around its own side. If the host
plant remains TOO stunted it may be necessary to remove some of the baby
barrels from the graftee, which can each be grafted to the top of another
cactus.

The grafting process can be VERY effective and result in swifter growth
for even some regular green cacti, tiny dwarf varieties that don't do well
in captivity on their own roots will grow larger, faster, and healthier
atop a host cactus. But they are also often sent too quickly to market and
haven't been hardened off after spending their lives in ideal conditions
for mass production, so can take all ones skill in not overwatering but
not letting them shrivel and fade. But they'll have been growing atop
their host since they were seedlings and by the time they're a size to
send to market, they've definitely "taken" and can eventually be as hardy
as the hardiest cacti.

The variegated and black and even occasionally the fully red grafts are
capable of blooming, but that's never certain.

-paghat the ratgirl



In article , "David E.
Ross" wrote:

On 10/24/2008 8:06 PM, Every time wrote:
Complete gardening newbie here.

Several months ago I bought a small cactus plant from my local garden
center here in Yorktown, VA. It has 5 cactus. Or at least 4 cactus
and 1 other kind of plant.

On top of a light green stalk was a bright red cactus... and it has
now gone all brown. The stalk doesn't feel alive to the touch, either,
and looks kind of dessicated.

I don't actually remember what the plant thing looked like, just that
it had nice purple leaves, which are now all crumpled and defunct as
well.

My question is have these things actually died? (The other three
cactus in the pot still look nice and green and alive). Or have they
gone dormant.

When I first noticed the red one had lost its color a few weeks ago, I
tried to water it...didn''t help. Prior to that I'd never watered the
pot at all.

Ihttp://www.geocities.com/nocturne_cvs/ExRedCActus.JPG

is a photo of it. The cactus in the middle is the ex-red cactus.

Any help appreciated.


Nurseries often sell plants contrived by grafting a colorful cactus on
top of a plain cactus. Such grafts often do not survive very long. In
any case, they are artificial freaks.

Made-up pots with cactus and other plants are also common. Too often,
the combination is not compatible. Sooner or later (more likely
sooner), some of the plants will die. Either the cactus dies from too
much water, or the other plants die from too little water.

If you really want to grow cactus, try my do-it-yourself potting mix at
http://www.rossde.com/garden/garden_potting_mix.html. Note the
proportions indicated for cactus. The key is that this mix will give
the excellent drainage required by cactus even if you over-water, but it
will still supply moisture if you forget to water. I've had excellent
results with this mix for growing ephiphyllum (a cactus). I also did
well with Christmas cactus until until the Great Freeze of '07 killed it.
--
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http://www.paghat.com
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