You'll get the answers you need in growing under lights forum.

nymickey, just plain cheap shop lights with T5, T8, or T12 bulbs (which ever is cheaper), will do just fine for seed starting. I Just use lightweight chain and "S" hooks to adjust mine. It works just fine. The "growing under lights" forum has a lot of good information but can get waaaay too complicated for just the average person wanting to only start seeds indoors. Good luck and have fun!

Agree that you don't need to order special grow bulbs for seedlings. Lots of discussions here about that fact. But if you want to use them for some reason then if they will fit will depend on the bulb.

Length isn't the only issue, so is the diameter and the pin distance, and if the ballast in the fixture will be strong enough to trigger them. Some of the chip board ballasts won't. Usually if they are the same diameter of regular shop light bulb then the pins will fit.

Dave

If you don't have the bulbs yet, consider using a warm white and a cool white together. You can surely get them in the right size for a shop light, for less money. One is stronger in the blue end of the spectrum, the other stronger in the red end. Together, they give a broader spectrum than either one alone. Grow lights give still more of the spectrum, but I'm not sure your seedlings will care.