Thank you in advance.

~MH

You water them as they need it, and you fertilize to promote growth and bloom continueing.
You keep them there all winter long and keep watering them about once a week. Do they dry down between the times you water? Or do you just use the schedule of a weeks apart when they are watered?

Now they are srhiveling up....the buds drop.

The "shriveling" suggests the plant is dry....but then if they don't get proper sunlight, they'll shrivel too.
The buds drop because: either too little sun, too much sun...we can dispose of that, improper watering...what do you think of that, or the room they're in is too cool or where they are put is in direct line with a source of air that dries out the soil faster than you want it to.

Your method is one of the ways geraniums are kept going after removing them from the cold air of autumn.
The other methods are to promote total dormancy by putting them into a cool room, with no light, no water and being left alone until we wish them to grow again--which is just about this time..February...when they are brought out of dormancy, cut back, given fresh potting soil, watered well to drainage, placed into a sunny window and wait until new foliage results---then fresh flowering results later...maybe until after they go outside.
The other way is to take cuttings and bring them along.

I'd say the sunlight has caught up to them. Through winter they receive very little sun and are kept going as well as we can keep them. But, sunlight in winter is not dependable...and we expect something like this to happen.

Now's the time to do as tho we had placed them into the cool room. Cut them back, about 4", clear them of all the soil from their roots, cut them as you think required, remove all dead branches and stems, all flowers that are dried up. Into a clean pot, with shards between the soil and the pot's drainage holes, fresh potting soil, watered to drainage, given good sunlight from a western, southern or eastern exposure....and no watering until new foliage re-appears. Then water as necessary but keep the soil on the damp side--but not wet, each time you water, water to drainage, dump the excess.
It might take as long as a week or two to show results...new budding leaves.

It might not show flower buds until it goes outside in May...but not to worry, the plant will come back, better than ever.

As the foliage appears, you can begin fertilizing about 1/4 rate every 2nd or 3rd watering. Increase fertilizer only when the foliage suggests it needs it. Every day or two, turn the plant 1/4 turn so that every day the entire plant gets its fair share of sunlight.

Outside into a container with potting soil and as much sun as you can give it. A northern exposure is not what it wants...southern or western is what is called for.

I use the cool room method myself...I have a coldcellar and along with my preserves, are kept there, asleep, dry as all get out, not a drop do they get. I have 7 plants...5 of them celebrating their 8th birthday.
I have, in the past, brought them out as early as mid February, ....but recently we have been in the Caribbean at this time so we get to it about the ides of March.
At this time the sun is fast giving back what plants need and every day the sun gets better and better.

You can decide whether you want to cut them back now, or place them where they can be left dormant, and bring them out next month.....but the plant deserves as much sun as you can give them.

About watering on a schedule...not dependable. Through winter, the plant isn't using the water like it used to...and too much water then sits under it, and if left there, and watered more and more every week, soon begins to rot the roots. You can tell if this is happening when you unpot them. In any case, you are going to clean all the soil off the roots, and remove any damaged roots...they might even smell.
The clean pot and fresh potting soil will solve that.

This is the first year they did not continue to flower throughout the winter. They're in a sun room and get at least 6 hours of direct southern and western sun on sunny days. Sometimes they get more if I move them throughout the day.

I water them once a week if they are dry. They have to be watered daily in the summer, so I know they're partially awake. I gave them a half amount of Shultz Plant Food throughout the winter (probably twice a month) and have just started with a higher middle number to try to encourage flowering.

I usually don't put them in the garage for that long before bringing them inside. This year we got a cold snap early, so I had to get them out of the cold sooner than I planned. Our garage is insulated. I like to give my outdoor plants a spritz or 2 of insecticidal soap before bringing them indoors, so they stayed huddled by a south facing window for 2 weeks. I'm guessing they started going dormant? Do pellies go dormant?

So the plants are leafy and healthy. It's just that when they form buds, the buds shrivel and die before opening.

I hope that helps. I do appreciate the response.

Thanks!