I advise you not to bother.
Mine has been up for a week. We sawed the bottom off and it's in a stand with water but it is already brown and crispy and dropping needles all over the bloody place. It looks dreadful.
It's not near a rad and our house is only heated a couple of hours a day as we're both out at work.
Theren is no way it's going to last until Christmas Day. I'd be surprised if it lasts until this time next week. Some of the lower branches are bare.
Pissed off.