Man if you can reach 70 days they will look crazy.
If your goal is 10 weeks you need to not start flushing until after 8 weeks.
I think my strains push so long because I keep feeding them light feeds longer than most.
The last 2 weeks is a flush so water, molasses and microbes for 2 waterings. The microbes mine the dirt and help release nutrients. (This during the flush period helps clean the soil and release small batches of nutes each watering).
Then next watering some meta-k, microblast, and big blooming guano, molasses and microbes.
Followed by 2 more waterings and repeat.
The microbes paired with your long flowering plant will carry her the distance. The microbes will give her exactly what she asks for.
You will know when senescence approaches not because a couple leaves yellow, but when the whole plant loses its green and fan +sugar leaves start to brown and die all over.
The leaves Browning and dying is my sign to just flush from there on out.
The plant will start to consume it's fan leaves for food for that final push. So letting them consume these leaves at the end gives them a little boost.
It costs a plant less energy at night to consume it's stored nutrients. Than it does to photosynthesize new food during the daytime. Since the plants use their stored energy mostly at night. The final couple weeks benefit from an extended dark period.
It will help with the rate of senescense. If your not ready to drop your light hours at the end. Then reduce the light output.
This will give them their 10-12 hours of awake time. But the light input over that time is reduced. The plant will attempt to compensate for the change in season by speeding up maturity. Pushing it's final foxtails and calyx's out.
This reduced light output will also help preserve extra
terpenes by introducing less heat into the space.
I switch the hps out at the very end because the light output drops by almost half. But the par is wider and larger at a higher energy level of color (blue). It also pushes out that uv to help increase resin content. Aaaand the mh runs cooler allowing you to lower the temps.
When you (by eye) notice the wave of milky trichomes hit and spread all over you will know harvest is near.
Make sure to let your soil approach dry then give her final 2 days in the dark. The goal is to get her to bone dry by the last day. It makes her think death is near. Helps with the last push.