Fermenting stopped early?

I am new to brewing, have only brewed three batches so far.

The first batch was a Honey Weizen that I just bottled last weekend. When I checked the gravity on it, it was right around 1.018 or so...just below the 1.020 mark. My OG was right around 1.048-1.050 which is where the kit said it should have been. I was just thinking that it was suppose to be getting closer to the 1.010 mark? I am pretty sure that it was done fermenting though. The bubbles really slowed down in the last week and there was pretty much no activity on the air lock on Saturday when I bottled it. It fermented for a total of three weeks.

I just wondering if I am doing something wrong because my second batch is Hank's Hefeweizen that I got from Midwestsupplies. The OG was right on where it was suppose to be again around the 1.050 mark. After two weeks in the fermenter it is still bubbling in the airlock, but pretty slowly, acting a lot like the first batch I did. I took a gravity reading today because I was switching out the blow off tube with a regular airlock and took a sample since I had it open anyways and the gravity is at about 1.020 on this one. According to the directions the FG should be around 1.010-1.012.

Both batches fermented in the mid 60's. In fact I just took the temp on this sample I got and it was at 66 degrees. So any thoughts on my gravity situation here? Just worried that I am doing something wrong and when I brew more I'll be making the same mistake.

Maybe this will help you:

http://blogs.homebrewtalk.com/ArcaneXor/Fixing_a_stuck_fermentation_101/

Depending on the yeast, the temp might be a little low. It sounds great for the first week to keep it from producing unwanted esters.
You could extend you primary for another week, or after the first week and the Krausen has dropped you can let it warm up to around 70F to condition. I would not want to go over 80F during this time.
Are you keeping the bottles from the first batch cool? That high of a FG compared to the expected FG might become an issue if they are now sitting at room temp.

ArcaneXor said:

Maybe this will help you:

http://blogs.homebrewtalk.com/ArcaneXor/Fixing_a_stuck_fermentation_101/

Click to expand...

Thanks for providing the link!!! I've been searching past forums for hints on dealing with fermentation problems, but your blog on the issue is the best--very thorough and helpful!

Thanks for the replys! Over the past few days I've let this warm up a bit and agitated the wort/beer a bit in the carboy and it seems to have a bit more activity in the air lock. I'll probably check the gravity again tonight and see how much it has changed. I may have to let this go for yet another week before bottling, unless it has dropped near to the target FG in the past 3 days.

Its been about a week since we bottled that first batch. Might open up one of the bottles tonight or tomorrow to see how that is coming along.