Nothing, just go with pure enthusium , and attention...works everytime
You can, drop the seed in a cup of water overnight, usually till it sinks , then plant it in a small cup of
promix or coco
Or you can take a really clean plate clean hands and moisten a paper towel , place the seeds on the towel, cover the plate with saran wrap, place in warm 75 deg dark spot and check for sprout , takes approx 2 days ....
You can use rockwool, peat pellet, rapid rooter etc to drop seed into in a humidity dome /tray....
All will work, actually never heard of purple stufF, but im old and dont get out much these days, just do it the old fashion way , it will work, trust me