I Dont think they were getting enough light when they were inside... kind of small for 2 1/2 weeks. I generally dont feel comfortable putting my plants in their outdoor location until they are at least a month old. Putting them outside when they are a little stronger and more mature really increases your chances of success.

If Im starting it outdoors I put them in cups before I transplant them in the ground. It can be rough out their for seedlings and starting them in cups helps.