No.
The carved pumpkins you refer to, are called Jack-o'-lanterns. As Wikipedia's "Jack-o'-lantern"'s page reveals, they are representations of "the phenomenon of strange light flickering over peat bogs, called ignis fatuus or jack-o'-lantern." These lights have ghostly connotations, but a whole variety of folkloric origins tries to explain the phenomena in different ways.
None to do with protection against vampires.
In fact, before these carved pumpkins become popularly associated with Hallowe'en, other vegetables were lit up and carved in similar ways, including turnips, mangelwurzel and swedes.
The term jack-o'-lantern originally referred to a night watchman, that is, a "man with a lantern".
Orianally it was to scare away the Vampires. This is because people beleived in Vampires back then.
there's a rumour that people use pumpkins as decorations to keep vampires away from houses during Halloween
The reason people put pumpkins out on Halloween started a long time ago. People believed vampires and mythical creatures were real and were going to "haunt" them. Myths say that vampires and mythical creatures such as werewolves hated the smell of pumpkin and got scared of the jack-o-latterns on them, so people put pumpkins out on Haloween to keep away the vampires and other mythical creatures.
No, they carve pumpkins for Halloween.
Halloween used to be a day where all the ghouls are allowed out for one night only that is why people put pumpkins outside to warn of evil ghouls
The original reason for Halloween pumpkins was the belief that the scary face carved into the pumpkin and illuminated by a candle inside the pumpkin would scare off the creatures that would be prowling around on Halloween. Few if any people still believe that, so the practice is continued just for fun.
Halloween lanterns are traditionally made from pumpkins; some people use plastic imitation pumpkins.
because its Halloween
Halloween is a time when you scare people and vampires and werewolves are generally thought of as scary!
because its Halloween
The farmer grew 100 pound pumpkins.The insides of pumpkins are used to make pumpkin pies.You cannot eat the outside rinds of pumpkins or watermelons.
It depends on what book/movie your in. Vampire diaries: vervain. Classics: Holly water, crosses, garlic. and there is even a myth that people put out pumpkins in halloween because it will ward of the vampires.