Bottle Conditioning -- Effects of Time

I'm trying to figure out what I'm seeing with my bottle conditioned beers. I bottle with sugar and wait the recommended 2-3 weeks. (Unfortunately, SWMBO requires all my beer to reside in the basement so during the cooler months, I'm conditioning at 60-65 degrees F at best, but I see a similar effect even during warmer months.) What I'll see is that for quite some time, the carbonation may seem overly harsh and I get a head that is full of large bubbles which quickly dies down like you would expect from a Coke rather than a beer.

However, I recently let the majority of a batch of IPA sit for 2+ months (I know...freshness...). The first few samples during the initial 3-4 week timeframe were as described above, but the rest of the batch has really changed. The head is thick, creamy, laces and sticks around for as long as there's beer in my glass.

What is the cause of this change? Is there any way to speed it up? I want all my beers to end up this way, but waiting 2-3 months seems less than ideal for many styles. The only thing I've been able to come up with is that the basement is keeping the beer too cool during the bottle conditioning phase and lengthening it tremendously. Any other guesses?

If there in boxes you can try a heating pad under the box and warming things up a bit. Around 70 is a great temp to condition at. Give it 3-4 weeks at the higher temp (I like around 6 weeks) then put them in the fridge a few days. That should get you close. They take a lot longer to condition at cold temps.

The temperature is it... 60 to 65 will mean a long time for bottle conditioning. Don't be afraid to condition in the 70's. The beer will carb faster and be drinkable sooner! Right now I'm drinking an Irish red that was quite flat and stale after 10 days at 65. At 16 days it's almost there - but still needs a few more weeks.