Buds are shriveling up and falling off

[Virgiljeff]

I am trying to regrow orchids
I am very successful in growing buds
But then they shrivel up and fall off before the bloom
Any suggestions ?
Posted via Mobile Device

[raybark]

There are a number of reasons that may happen, including:

• Insufficient humidity
• Hot or cold blast of air
• Sudden change in temperature
• Excessive sunlight
• Mites
• Insufficient water - i.e., underwatering or a poor root system that cannot take up enough water to start with.
• Fumes (ethylene) from a dirty or poorly-tuned gas flame.
• Ethylene from ripening fruit.

There are probably a few more I’ve neglected while having my first cup of coffee, but if you can explain what type of orchid we’re talking about and the details of your growing area and watering habits, we might be able to narrow it down more.

[Masaccio]

Trying to narrow down the reasons posted by Ray to those that might be more commonly and repeatedly encountered. Althought "fumes" sound like the most likely of culprits for this particular problem, it seems the least likely for most households.
In this case, as Ray suggested, specifying the type of orchid, and even better, posting a photo of a representative sample plant, along with the blighted spike, would also be helpful to diagnose this recurring problem with several plants -- as you suggested.
Orchids in general are real soldiers in survival. The fact that they spike and make buds isn't necessarily a sign that they are particularly happy. I concur with Ray that inconsistent care could be the problem. Successful care for orchids, although not particularly complicated, does require a "mindset" of consistent care, a step above regular houseplants. It might be a matter of scheduling your orchid care, and not assuming that they will okay if you miss a day or two.