Hi Mary, I am currently in the process of growing over 175 seedlings and my method is to start them in jiffy pots and that way I don't have to worry about the root system when I upgrade them to 1 gallon pots. The 1 gallon pot should hold you over all winter in a greenhouse. You will probably have to move them to 3 gallon pots at the beginning of next spring but a 1 gallon pot should do the trick for the winter. If you already have a heat mat then that is great. I actually turned my garage into a greenhouse and have a little heater that I use to keep the temp over 70 degrees. The mix I use is called Metro-Mix 300 which is a light mix that has perlite already mixed into the soil. I normally cost anywhere from 15-17 dollars a bag and covers 2.8 cu ft. You will need to use grow lights but I use LED (red/blue) lights that I bought off Amazon that work great and keep the electrical bill down. I also use white lights. I turn on the white lights during the day and then switch to red/blue lights at night. Other people may have a different method but this worked really great for me last year and my plumeria's bloomed even during the winter in my greenhouse. I did not use any fert over the winter but this year I am going to try some hydro fert made for indoor growing to see the results. You will probably struggle with mites....I think we all do. I use Bayer 3-1 spray the keep the mites/bugs down. If you do come across mites even with the spray then i use wet paper towels to run the leaves and kill the mites. Good luck with your seedlings.

Quaching, do you use LED white lights? So I need to get some lights for daytime too. So good we have this board here, love all the advice posted! Thanks for the ones related to seedlings.

Mima

Hi Quaching. thank you for your helpful information. Would you know at what stage they would go into Bill's mix? The one made with pumice, turf something and big R? that's what I use for my other plumeria in pots. this is a learning process as I've never done the seeds before. Poor things, Ill probably hasten their demise by not really knowing what Im doing. Thanks again. If you think of anything else I need to do, please let me know. Mary

I've got two dozen seedlings that I transplanted into gallon pots filled with cactus mix and perlite and they seem happy, none have died :). I think as long as the soil is well draining they will be happy.

Hi Disneyhorse. Thank you for your input. I love the shared information here. Can I ask a question, mine are about 2 inches tall and have three leafs at the most. do you know when I should feed them and if I need to, with what? I think I need to keep them growing over winter by putting them on heatmats and using grow lights, correct? You guys are such enablers. I never wanted to do seeds, but this year Vienna Rose changed that! they are so darn cute. all the different shapes, short, stubby, tall, thin, different leaf shapes, colors of stems. Like I really need more things to obsess over! thanks again, Mary

I put mine in little pots when they get there 2nd true leaves. I put them in the mix they will be growing in till they are ready for bigger pots. So you can use your regular bills mix and everything when you put them in little pots. I use short fat disposable cups with holes in the bottom sides
Mindy

Mine are just getting fertilized right alongside the big guys. Hasn't burned or killed them but I'm pretty lax about fertilizing.., they get Epsom salt, osmocote, or miracle gro every two weeks I just rotate randomly and feed on the light side. My goal is survival though, not tons of blooms just yet.