Right now I am favoring Jiffy peat pellets or Hoffman's seed starter 2 ways...either straight out of the bag or mixed with perlite for plumeria seeds. I also used Root Riot plugs. It took my seeds longer to germinate in those plugs than the other methods. They are sponge like and it is almost like they held the seed too tightly
all of the seeds have sprouted and the seedlings look good now. I'm thinking that maybe this particular brand of plug might be more appropriate for small cuttings. My 2 cents worth!!
On a side note, my honey dew melon seeds I saved from last summer, have sprouted under the lights!