I started seedlings in June. Some are developing a thicker base, some are skinny. They are about 4-5 inches tall. I have small led 10 watt grow lights on them. I planted 3 or 4 per 6" pot. Some have said on the plumeria forum that the stems should be thicker. I don't know what to do to accomplish that. I don't have sunny windows and it's too hot to put them outdoors, I think. I have lowered the light so that they are closer to the plants. Any suggestions?
I've also been told I should transfer them to their own 1 gallon pots. Is this the right time to do this?
There is so much information about cuttings but very little about plumeria seedlings. I have 19 of them growing and I hate to mess this up! Thx!

@drdawg

@Imroberta, welcome to NGA. I'm not very active here any longer, but your question was referred to me. I've grown seedlings by the many 100's.

First, ignore, totally ignore those who tell you that your seedlings should confirm to some sort of shape or size. They don't know what they are talking about. Every single seedling will be unique, even those from the same seed-pod.

I transplant my seedlings from a "community pot" to their own 4" pot when the seedlings are about 4" tall. I think that your seedlings now need to be in their own pots. When they are twice that size, move them into gallon pots. My seedlings have always grown outside. I'm in Vero Beach, FL, and though our summers aren't as hot and certainly not as dry as your climate in AZ is, I've never worried about heat. I will allow my seedlings to get a few hours of early morning sun and/or a couple of hours of very late afternoon sun, but from about 10:00 AM till 4:00 PM, they are shaded. I had a lot of plumeria in-ground, and having these large-leafed small trees, the seedlings did very well underneath them. Any sort of fairly well-leafed tree will do. If you don't have this, how about a porch that might get only a few hours of early or late sun? I'm sure you've got somewhere to put these few plants. You should plan on watering your seedlings every day or two. That sort of depends on the amount of sun, the temperature, and how low your humidity is. Our humidity averages above 80% all year long, and that helps these tropical trees endure heat. You won't have this option, so anything that you can do to increase the humidity around the seedlings, the better.

Thank you for your reply. Your information was very helpful!! I appreciate it.

You are very welcome, @Imroberta.

This is the first time blooming of a seedling from the seed-pod of Pink Lady Bouquet. I'll see if she's a candidate to name after 1-2 more blooming cycles. This is a nicely growing 3 year old seedling and now has 6 tips. She's about 3' tall. I expect these flowers to become "rainbows" in subsequent blooming cycles: pink, yellow, and white. Time will tell.

Beautiful! That's exciting! It's does take some patience.
I have a mature tree that is sterile. I decided to take a chance on buying seedlings on line. I also have 3 small plants that I purchased from a box store. Everything is doing well. Im very excited to see them all develop.
Thank you again for your help!

@Imroberta, what do you mean when you state that you've got a sterile plumeria tree?
Is this a variety of Singapore?

Your seedlings look great. I have good luck wrapping them in a damp paper towel in a ziploc bag and put it on the window sil that gets partial light. Once a tiny root pops out then I put them in tiny cups with lightly moist cactus soil. All my seedlings are different. Some are skinny and some are thicker. some grow fast and some not so fast.

Yes, the damp paper towel technique is a tried and true method of germination.