Light is how plants make food. Not enough light=not enough food for proper growth.

Nobody can say for sure if your window light will be enough to maintain strong, healthy growth. In most cases window light isn't enough, but sometimes it is. Just depends.

If you have to make room, then try to get the plants outside as often as you can weather permitting. Of course, harden them off first rather than just set them outside for a full day right away.

When it is considered safe to plant outside in your area? With 8" transplants you have a very nice transplanting size right now. If you are using floro shop lights their usefulness is running out as the plants get taller.

yes, I am using regular shop lights and soon there will be no much space for them under it anyway; but no, I cannot plant outside yet -- night temps are in low 40s, and lots of rain and cool weather ahead for 2 weeks. I will try to remove them from shop lights and see what happens. Thank you.

If your night time temps are reliably in the low 40's
you can plant outside. You will have to protect them
at night though with buckets or something. Be sure to
take the buckets of in the day time so they don't get
too hot.

here is my forecast for next 10 days: rain for two days, mid 60s day temp, mid 40s night temp; then sunny/cloudy for a week with mid 50s at night, mid 70 -almost 80 day temp, very little chance of rain. Can I plant them out this weekend?

Seems to me there is a middle ground between having them either under lights or planting them in the ground. Personally, if you still have a couple of weeks before ideal planting out, I would re-pot any that needed it into larger pots, and after doing a gradual hardening off so they get used to real sun slowly, put them out during the day and tuck into a garage or entryway at night until you are sure the ground has warmed up and weather has settled.

It's also easy to nail together pieces of lathe or thin boards to form "window" sections, then cover with plastic sheeting, and put in screw eyes at the corners so you can wire them together to form a simple above ground cold frame that comes apart for flat storage. While it's a bother to have to cart plants out in the morning and in at night, it's only for a couple of weeks.