I'm having a problem successfully grafting my San p x cereus seedlings. The seeds sprout easy enough, but tend to die off (not sure why) by the time they get to "J" below. So they grow ok for several weeks, then start to die off. Most tend to be albino (not all,some are green), I have tried to graft them onto per, but as they are from G to J stage, I only have about 3 - 5 mm to work with, & as they are maybe 1 -2 mm thick, even a sharp razor blade tends to compress (squish them slightly). Ideally I can graft ok when seedlings are at the L to M stage, is it possible to graft seedling before the column emerges, ie pre K?...as they never survive to the K stage. any suggestions?