Plants at 15 weeks flowering, Is there a way to force them to finish already?

So, I'm wondering if there's a way to make my plants finish up and start dying already... I'm on week 15 of my flowering phase, and while they are nicely frosty, with many red hairs, the top colas still have a lot of white pistils, with some foxtailing going on, and the trichomes are still mostly clear.

It seems that this is just a super slow maturing Indica/Sativa cross (I actually don't know what the genetics are, it's from a bag of mystery seeds I acquired), but I need to chop soon and I'm hoping that there's a way to force them into their peak potency. Will keeping them in the dark for 48 or 72 hours help the do it, or do I just need to either a) wait it out some more or b) chop before peak potency? Thoughts? I appreciate the help.

Here are some pics from about 10 days ago. they haven't progressed much since then.

And yes..I have had some nute lockout issues, but started my flush about the time these pics were taken.

What kind of light are you using? They look like they dont have enough light or re-started veg a little. Have you checked for light leaks?

In any case they should be chopped. You can get plants that never really stop growing calyxs/new bud

look at the leaves , are they short n fat or skinny and long ? if there sativa it can take upto around 15weeks. i would give them more dark time. maybe 15hrs dark time.your not opening the growroom in the dark phase are u ?

Like Small said,, Looking sativa dominant to me. I've had them go almost 18 wk a couple times.
From the pics,, I'd guess your close. Maybe 2-2 1/2 week if you wait for the trichs to cloud near 100%.

Could pull a bud for tasting. Probably help you decide better.

You can try 11/13 light schedule, works for some sativas.

Thanks, I'll try lengthening the dark phase...i'm currently at 13 hours of dark. I'm pretty sure these are a Sat/indica cross, they seem to have the characteristics of both...somewhat narrower leaves and yet not super tall and stretchy. Definitely never exposed to any light during their "nighttime". I'll let em ride a bit longer.

You have good patience my friend. Co2 enrichment can speed up a third. What are your low temps at, that can slow things down too.

My "nighttime" temps never fall below 63 or so, upper temp during daytime is normally 70. Humidity at 45-50%. I've been sustaining myself with the last of my last grow (18 months ago!) and a few samples from this latest crop. I can afford to wait. I'm not enriching with CO2, mainly because as a T5 grower, I'm not sure it would do me any good...not enough lumens to provide for max co2 uptake. I have good air exchange in the room though, so they get lots of fresh air. I'll post harvest pics when the time comes. Thanks for everyone's sage advice.