Papayas

I planted these papayas from seed at the end of May and potted them up into this soil that I dug up from around my old compost bins 2 weeks ago. First time growing papayas so not sure what to expect, but I really want to keep them alive. I'm in zone 10a, it hardly ever gets down to freezing here, and I'll bring them whenever it starts getting below 10C. Any other ideas of what I could do to get these guys looking a little healthier?

they look great, for being only a couple months old!
but if you can get them into the ground, or into larger pots (13-15L at least) they will thrive.
Their roots might be as long as they are tall right now, and they want to go deep. Papayas can grow very quickly. They don't need nice dirt, they can take all sorts of abuse, but unless you have very big pots their growth will be limited.
In zone 10+ they should do just fine. I grow them in 9b and the tops get frostbitten but the plants generally grow back unless they're young or somehow compromised. We had hard frost in maybe August that killed the foliage and a few young plants so this summer I don't expect to get any fruit, but next year they should be back to business.

Just keep in mind- in my experience they're a tree that grows quickly and also dies quickly, very short lifespan. "Easy come, easy go" might be their motto. When they're going great, awesome, but maybe start new ones every other year or so, and don't be surprised if something happens. It's also good to have multiples in case you get all males that don't give fruit (my hummingbirds like the flowers, but I limit it to one male plant in the garden) or if you don't get the female or hermaphrodite plants you want (i know people who prefer the fruit of one or the other).