Under Hopped....can I correct

So last night was the first AG and first brew on the new rig. A few tweaks need to be made but all in all it was great. I did a 10gal batch of EdWorts Haus Pale Ale.

The problem: I was so concentrated on all the workings that I added hops for a 5gal batch vice a 10gal batch. I completely ignored my hand written notes with the correct additions.

Can I take the balance of the hops, add them to a gallon of boiling water on the stove, and add a half gallon to each fermenter. If so, how long to boil, should they be added on a schedule or all at once. The volume won't hurt me to much, I was a tad low on volume. My OG was a little low but I chalk that up to temp control and my process which needs to be refined. Thanks.

I did something similar. Take a gallon of water and add enough DME to reach your OG. Boil the hops for at least 60 minutes and cool. If you don't have DME try 1/2 gallon wort + 1/2 gallon water with a little sugar. Maybe even steep some crystal in it...

Thanks.

I have some DME but will pick up some more today after I find an online calculator to tell me how much I'll need. Thanks agian.

Did you forget to add 1/2 of each hop addition or simply 1/2 the bittering hops? Guessing the former...

If you don't mind using DME/LME, then I'd get as close as you can to your recipe and do a mini batch as previously stated... Remember that your boil volume will affect your isomerization too. If you use brewing software, then I would design a batch that is the correct boil volume to get the correct amount of hops for the smaller boil volume (you'll need a bit more than the other half... or... you'll need to boil the bittering addition a bit longer.

oh... and if you don't use software, then you can go someplace online... I like http://www.hopville.com