Your basement is too warm for wintering figs.
You should have known that from your own past experience.
Once dormancy is broken, I know no safe means of stopping it.
A strong light will prevent "leggy" (long) growth.
Do not ferilize and provide minimum watering.
Next year, try your cold garage. My experience:
below 20*F fig (twigs) may die, roots can take lower temps;
above 40*F figs may break dormancy.
You still have ~2+ more months inside (frost-safe).
Then bring out in shade for ~2 weeks to harden off.

Also, if it is easy to reduce the basement temp,
say to 45-55 *F; do it. It will slow down growth.

If it isn't too large I'd put it in front of a sunny window.

Yes, I know this is an annual problem. Thing is, I don't have a garage and as these are relatively young plants, I didn't want to risk leaving them outside. And, there's no way to adjust the temp in my basement.
I just was wondering if there was some way I could nip it in the bud, so to speak.
Seems like I need to hook up some lights to help them along.
Should the lights be very close?
Thanks.

Containerized deciduous trees that are kept as cold as possible for as long as possible into spring without being subjected to killing low temperatures and then moved outdoors into good light when they do break bud will grow with greater vitality and show a greater increase in biomass (more growth) than trees that are forced to or allowed to break bud prematurely, in spite of the belief that the "extended growing period" is good for them or somehow gives them a head-start.

I also feel the best thing you can do for trees that have pushed premature foliage is to move them outdoors into good light when temperatures allow and keep them indoors and as cool as possible in good light (unheated garage or shed near a window) when there is danger of exposure to frost outdoors. This is as close as it gets to nature after premature leaf-out, and Mother Nature has proven herself to be a good steward of our trees for a long, long time.

Unless you have a good light set-up and favorable humidity, indoor conditions usually cause enough foliage problems and inhibit photosynthesis to the unfavorable predicament where the tree is using more energy than it is producing. This weakens the tree, or in some cases kills it. Surviving trees are put outside in weakened condition with little or no energy to push a flush of foliage. Often, inexperienced growers don't acclimate the tree to increased photo-intensities, and the foliage experiences photo-oxidation (sunburn) and dies. The result is a tree that spends its pre (summer) solstice time recovering when it should be extending branches and growing more leaves. When the tree turns the corner (at the solstice) and starts to STORE energy for the upcoming winter, it has far less photosynthesizing surface to turn the sun's energy into food, so the effects of the early 'sprouting' actually linger into the NEXT growth cycle.

You should avoid early growth if you can - it doesn't help your trees in any way.

Al

Thank you Al for your insight...I will bring the trees outside.
My concern was that since they're potted the soil would freeze and kill the roots. We don't seem to be going below 20 degrees at night in my region. Do you think they can survive this or should I just haul them in at night? Not an easy task!>(

>>> I will bring the trees outside... (NJ Feb 16!)...
Are you out of your mind? A death sentence!

Please do 'some' homework, and reaseach this forum
with some 'key' works regarding your problem/interest.
You will find plenty.

At some point you need to figure out next year where to store the plants for dormancy. So you have no garage , basement to warm for storage, then perhaps inground then wrap well for winter is your choice for next season. As for now i would imagine in NJ its still too cold to bring outdoors as the daytime temps would kill a tender plant.The key word in Taplas post is bring outdoors when temps allow which is probably in the future as your zone gets warmer. I do this with my containers stored inside garage and bring onto the driveway when temps warm up and back in at night cause temps drop and are to cold this enables me a head start in my area. But i do not bring outside until daytime temps are at least 50 plus outdoors and place on driveway which warms to the sun then back in at night. But you need to solve your problem and figure out a solution for next season, probably put in ground if no other choice for storage thats suitable.
For others reading this post before buying any plant one should have an idea on the care of that particular plant.Its like jumping into deep water not knowing how to swim. Now what? Im not trying to be harsh in my words and wish you the best. ; )
Martin

What Diesler said.

You're ALWAYS going to have problems re. early leaf-out with containerized trees because the soil mass warms soo much faster than that of trees in the landscape. Still, try to keep them as cold as you can for as long as you can. Once leaf out does occur, do the figgie two-step as Diesler described - outdoors on >50* days & indoors near a bright cool window on cool, Al

OK, OK!
I really don't want to commit figicide.
My options are limited in terms of bright, sunny window; hauling these pots in and out; limited inground planting space, etc.
So, I'll just have to hope for the best. I was just wondering if keeping them dark would help retard the growth, but it seems its more a function of temperature.
At any rate, thank you all for your input.
I'll try to do the 'two step' when weather permits.

Hi figtreeundrgrnd,
Do not panic.
>>> My options are limited in terms of bright, sunny window; hauling these pots in and out; limited inground planting space, etc.
If I were you, right now; I'll do the "bright, sunny window" thing. And will deal with other problems later.
I do wish you all the good luck and happy figging...

Please dont think our comments are harsh ; )
Also the comments here will help somewhat such as what Gorgi said about a strong light, i use a type of flourescent light indoors for this season only, yes you should put as close to tops as possible long as its a cool burning type such as a flourescent, otherwise not so close.
Its too bad you cant put inground but i understand about limited space i would have more plants if garage was bigger to store them.

Thanks to all for your help. No offense taken;>)
I had some help bringing them up from the basement and have them by the back door which I leave open for light (when temps permit).
I already have two inground and as the backyard is "communal property" I don't want to over step my bounds. Besides, the most sunny places are already occupied. Hence, the pots. It may be backbreaking, but its a fig lover's dilemma!>)
I'm trying to root a branch from a neighbor's black elongated fig (don't know what it is)...that would make six! At some point I have to put the brakes on!
Thanks again for all your help.