Is it possible, that your plant doesn't receive any or enough light (sun light that is) ?
I have one, which I placed on the east side, and it gets morning sun. It also gets plenty of humidity, but that's nature's doing not mine :). My Diffenbachia however, is thriving and looking strong. Good Luck !!

Variegation is often unstable in many plants, with reversion to the all green form the result, but it's much more likely a light issue (too little), as Bella suggests. Occasionally, variegation is affected by changes in pH at the cellular level (little to do with soil or soil solution pH) and the presence of certain elements in the soil (this is what actually makes hydrangeas change colors between pink and blue), but the odds still overwhelmingly favor it being light-related.

Al

Rhonda, is it the leaves that were already on the plant that have changed color, or new leaves that have grown since you bought it? Can you describe it's location since you brought it home? Are new leaves emerging?

I don't think 5 months is long enough for a Dief to have cycled through to all new canes so my anecdote probably doesn't answer your question. But I've had a Dief for many years that has gone from being a variegated potted plant, to a pathetic almost forgotten stick barely alive in a cup of water, and back to being a potted plant that had regrown enough to be divided recently. Years ago, I remember it being distinctly variegated but all of the canes of the current generation are plain green. Until I read your question, I hadn't even registered that fact. It gets burned spots from any amount of direct sun but it has greatly expanded "in volume" since moving to AL to spend most of the year on my covered front porch. It may just need a more gradual acclimation to direct sun and I've failed in that regard. If memory serves back to when it was variegated, even the variegated leaves would lose most of the variegation as they aged.

If your plant is outside, you may want to ask on the FL forum also since FL is its' "own little world" in regard to growing things outside.

Rhonda, without knowing the care your Dief is getting, it's difficult answering.

Is it growing in or outdoors?
What type of light?
Have all leaves reverted to green?

Although Dieffenbachia's are grown as house plants, can adapt to some shade and dry air, the perfect growing environment is natural warmth, humidity and bright to bright-indirect light.
Soil should never be soggy wet, otherwise it will rot.

I can't tell you the number of times people have posted pictures of their new, beautiful, healthy, colorful Dieff. It's set in their a/c'd home, 'dry air,' tucked in a corner, 'stuffy, dry air and deep shade,' then wonder why their new plant is doing poorly or died.
Out it goes in Thursdays trash.

If you can provide us with more information, it'd sure help. A picture, too. Toni

Dieff is a tropical plant; tropical plants need certain care, which means, parroting the tropics to a degree.

Thank you all. I have my plant indoors in an eastern window. However, the tree branches in the yard were blocking a lot of the sunlight. I had hubby cut some branches and now the light is much improved. So hopefully, the varigation will return. The plant otherwise appears healthy. I think the humidity is good. I have a waterfall fountain in the same room and the pot is sitting next to my orchids which are in a tray with stones and water.

Rhonda, sounds lovely. I'm sure now that the branches are cut, your Dieff will enjoy extra sunshine.

What type of waterfall/fountain do you have? Yes, Dieffs need humidity, but not wet feet. Toni

Thank you to every one for the great advice. Since the plant is getting more light the verigation has returned. First there was a spotty leaf and now a new one coming with a creamy white center. Here is a pic of it.
{{gwi:96994}}