This will be a supplement to Pete's recent post regarding "winter rooting and what we have learned".

I wanted to share my observation from this past winter/spring attempt at starting cuttings.  I'd say about 90% of my cuttings started using my favored method of 32 oz deli container in a covered Rubbermaid type container with heat mat and 60/40 sifted perlite/Mircale Grow Organic Potting soil.  (Note: watch out for fungus gnats with the MG organic potting soil.  I always use WDG gnatrol at the first and subsequent waterings.  If I see any sign of those flying beasts I also use a spray with pyrethrin).

I started to pay careful attention to cuttings which did not root/show leaves or died shortly after (1-3 weeks) showing roots, leaves or both.  This is what I found.....no suprise.....an over abundance of water killed them brought on by uneven distribution of perlite and potting soil.  Either the mix showed areas where the potting soil was the majority of the mix through the height of the deli container or the potting soil had accumulated at the bottom of the container, either was fatal.  The attched photos from the same deli container may not be the best, but I hope you get the idea. 

My corrective action was to increase the amount of perlite in my starting mix to about 80/20 perlite/potting soil.  I also watch more closely as I fill my deli containers.  If it appears as if there are areas of highly concentrated potting soil I will empty the deli container (sometimes 3 or 4 times) and refill until I am satisfied with the uniformity of the mix in the conainer.

i mix them twice. before adding water and after. to make sure water doesn't settle too much, i also mix the soil while potting cuttings. typically, they come out without problem. but i do notice some 1 gal not draining as well as others. this yr, i was little more careful with mixing and so far no problem.

I used a cement mixer this year and mixed till it was completely uniform. I do believe it makes a difference in draining.

Using orchid soil might help.