I use 3 1/8" deep cells (1801 tray inserts
) filled with Pro-Mix BX but a 3:1 perlite to peat moss mix would work just as well. I use a tall humidity dome and keep them really well watered
. With the perlite, they won't be waterlogged and rot. I insert the cuttings vertically with the top exposed. The first growth I see is usually callusing which then produces leaves. Sometimes I see green growth from the other buried end. My grow lights are just above the humidity dome.
To stimulate root growth, I water with a liquid fertilizer with a high phosphorous number 9-45-9, micronutrients and seaweed. I also use it as a foliar feed.
I get around 100% of my root cutting to turn into plants.
I want really good root development (it will be fibrous rather than woody) to I let the plants get pot bound. If the top growth gets to be a jungle, I'll cut back the leaves to an inch or two. They resprout very quickly.
When I plant out, I wound the roots and correct the pot bound growth by slicing a cross about 1/2" deep across the bottom of the root mass.