Question
Hi, I have a pair of 2 pale pink geranium plants which I have over-wintered now for 5 years successfully. They are gorgeous due to their pale color. However, I think I neglected them some this winter, not watering enough. It is odd, but they are well-attached to the soil at the roots, and have some nice green leaves coming out of the tips, but the middle of their stems are quite soft, as if dying. I put them on the porch, watered well, yet I wonder if I should cut them back, or maybe it is too late to cut them back? The center part of these stems are very soft, and I am concerned. I have kept them for 5 years, even though geraniums are technically annuals. Please tell me what to do to possibly save them. Thank you.

Answer
First, I apologize for your terribly long delay.  We had serious technical problems that caused a complete crash. Now we are back up and running.  I hope I'm not too late.

Geranium stems are built with perivascular fibers -- long strands of cells that create the plant's interstate highway, strong because they are fortified with tough, woody, water-conducting Lignin and Cellulose (aka "fiber").  Lignin is the stuff that makes tree trunks strong.

Lignin and Cellulose are invulnerable to insects and bacteria. But not to molds and fungi.

In fact, molds and fungi are what makes dead tree trunks decompose.  They are the forces that convert wood chips into compost.

As a plant grows, its interstate fiber highway expands.  The Lignin and Cellulose grow thicker and tougher to support more trucks, more water, more minerals.

What could go wrong?  A beautiful, healthy geranium with an icy, lovely pale pink color?  

Symptoms similar to the ones you describe is found in Geraniums younger than yours, caused by various species of the Pythium fungus and sometimes referred to as the disease "Black Leg" that happens when the wrong kind of fungus creeps onto the highway: http://blog.lib.umn.edu/efans/ygnews/diseases/

Geranium cuttings may take root in sand or soil infected with the wrong kind of fungus.

You use the word "soft," not a healthy symptom.  The bad fungus -- for Black Leg, that would be the Pythium gang -- gets on its motorcycles and travels around roots, up thru the stem.  Or they perhaps are deposited as tiny unseen animalcules in search of adventure, attaching to a sharp slicing instrument some unwary gardener uses to harvest the cuttings thereby infesting Typhoid Mary-style every other plant placed into cutting service with Pythium motorcycle gangs.

What's missing in your symptoms are the words "black" and "cuttings".  So although Pythium infection may be common, it is not universal.

It is conceivable that in your desire to multiply your collection, having no other source for this pretty pink petal color, you perhaps took cuttings.

But you also judge your care was neglectful last winter.  This doesn't sound like someone who was busy expanding her Geranium collection, in the worst months of the year to do this.

Black Leg (how did it get this name?) is a common affliction in young plants, especially those that started out as cuttings.

Another common disease: A Bacterial Blight caused by Xanthomonas hortorum pv. pelargonii, which attacks MATURE Geranium plants:

http://www.pocketdiagnostic.com/uploads/File/Datasheets/Xanthomonas_Data_SheetWe

Yes.  Mature.  As in 5 years old.  The ones that were cared for, doted over, monitored, pruned, carefully depetalled and tended thru one winter after another, year after year.

In fact your Geranium collection may have suffered from this disease for YEARS without showing symptoms.  It spreads from cutting tools, or as simple as a splash of contaminated water, or even on the tiny toes of little insects.

The Xanthomonas genius in fact causes many a gardener headache.  However, it is the subject of my favorite online video, produced by a U Mass botanist on a trip to Bangladesh:

http://extension.umass.edu/floriculture/fact-sheets/bacterial-diseases-geranium

The video helps illustrate how the interstate highways of plants like Pelargoniums are clogged up by alien invaders, in this case the Xanthomonas.  

The outside lanes of the highways are saved for the Phood trucks ("Phloem") and the inside lane is saved for the Water trucks ("Xyl. A layer of vascular cambium is located between Xylem and Phloem. The roots of Dicots are formed with Xylem at the center and Phloem outside Xylem.

Lifespan of plants

http://www.wsl.ch/dienstleistungen/publikationen/pdf/79_3_7276.pdf

http://lifeofplant.blogspot.com/2011/01/stems.html

When fungi or bacteria get in these highways, they effectively clog the highway.  Affected plants cease to thrive.

Yes, this is such bad news.

However...

With all the research being done on these plants and this disease, I would find a local chapter of your Geraniums Society, and see if they have comparable plants in a comparable pink.

Do not reuse the pots without sterilizing; do not re-use the soil; wash your hands THOROUGHLY after touching these infected plants.  Find yourself some nice new ones in a favorite color.

Regards,

L.I.G.