Spinach madness!!?!!!

This is the third year I've tried to start spinach indoors and it's bolting at 65 degrees under shop lights! The two years before that I figured it was temperature in my grow closet. This year I'm in am open room on a rack with fans. What gives?

About half of the spinach varieties that I grow bolt immediately after sprouting. About half grow huge leaves and flower late in the season. It's not possible for me to be able to tell which is which based on descriptions in a seed catalog. Here's an example: Two different varieties growing side by side. Get out your magnifying glass to find that plant next to the red dot on the photo.

Could it be the roots are cramped, causing stress which is triggering the bolting?  Or uneven watering?

As you've discovered, temperature isn't the only trigger for bolting. I'm suspecting other triggers are contributing to your problem.....
...confined roots. I start my spinach in containers (to avoid cutworms problems) and transplant them into large growing beds when their first two true leaves have developed, but before the second set shows. Leaving them longer means too much root development. If the seedling is still in a little grow-cell, then the roots are crowded and signal the plant, often resulting in bolting. When I first tried spinach here, all of it bolted because I left it in the little pots too long.
...too long a light period. Long days trigger bolting in spinach, more so than temperature. Thus spinach is often grown as a spring or fall crop, where short days are gradually getting longer or long days are getting shorter. So perhaps you may wish to check how long you keep the lights on.
...soil dried out. If the roots get dry, especially if the plants wilt, spinach tends to bolt.

There are varieties that are more bolt resistant than others. Perhaps trying one of those may solve your problem. Off the top of my head, I think Tyee is bolt resistant.

My tactic with greens is to grow a wide variety of different species, so that when one bolts or gets pests or whatever, another is coming into its own. My range so far includes: spinach, mustard, some kind of local mustard thingy, kale, parsley, lettuce, arugula, claytonia, mache, sorrel, and some others. Sometimes there's something that seems disappointingly slow, and then it rocks when the quick grower fails.

They have been in small cells for about 10 days. There aren't any roots coming out of the cells from what I can see. I'm thinking on giving up on spinach of this kind and going for Malabar etc. This just isn't worth it. I dial my homeade mix, watering and organic fertilizers so it's pretty much no work for me. I'm not going to beg spinach to work for me. I'm encouraged you had the same issue with it being bolts. Thanks for the tips all.

Do I unserstand right - you are attempting to grow spinach inside??

Why not direct seed outside?
But for the record, I've never had good luck with spinach, even when I lived in Vermont.  I always grew beets instead, and harvested the greens to use as a spinach substitute.

I grow all my starts indoors before I set them out in the garden. It creates an awesome advantage against pests and weather. Since nothing really germinated in NY in February I get mature seedlings by march.

I will probably just dump the rest of the seeds in my salads raised bed, never had good germination sowing them in flat earth.