Messed up fermentation?

Hi. I've done natural fermentation with my dad since getting out of the Air Force in 2003, and every year we've done Concord grapes. We simply pick, stem, smash for about a week, strain, add sugar and put it in a carboy until March. It always comes out great! This year, we are also doing Niagaras, and I picked enough Niagara grapes to yield about 11 gallons of juice. Unfortunately, there was bad timing and some things came up at home and I wasn't able to get the juice strained and sugar added for an additional week. The upside to this is that it gave everything time to settle, and when I siphoned the juice off of the top, I ended up with relatively clear juice. The downside is that after adding the sugar and putting the juice in carboys, even after several days, there is no fermentation process whatsoever going on. I'm pretty sure the natural fermentation finished with the sugar that was present before I was able to get the additional sugar added. Is there a way to kick-start the fermentation process again? Can I add wine yeast at this point? Or do I just have 11 gallons of sweet grape juice? Thanks.

Phrank

do you have anyway of taking a SG reading? Hydrometer?

That's what wild yeasts are like.

Unpredictable, inconsistent and unmanageable.

They MIGHT work or they might NOT.

That's why we use prepared yeasts.

Yes you can add wine yeast.

Is there a time limit on when I can add the wine yeast? I mean, I don't have any ready at hand, so I would have to find some in town or order some. It's been at least 5 days with no activity. Thanks!

if you were looking for wild yeast originally, i wouldn't worry about time limits. it's not like it'll sour while you're waiting