Check for pre-flowers at the nodes where branches meet the main stem
Male plants form small round pollen sacs
Female plants form teardrop-shaped calyxes with two white hairs
Male flowers usually hang downward in small clusters
Female flowers usually appear closer to the stem and point upward
Look for pollen sacs opening on male plants
Look for pistils or white hairs on female plants
Inspect plants during the early flowering stage
Use a magnifying glass if the sex is hard to see
Separate males from females if you want to prevent pollination