Trichomes are extremely fragile and volatile at all stages. It doesn't matter if they are still on the vine or if the plant is already harvested. Exposure to excess heat, light, or oxygen can degrade or destroy trichomes. Also, their potency will fall if you wait too long to cure and dry the weed.

Do trichomes fall off during drying?

It's important to avoid losing trichomes during the drying process by not letting your branches hit any surfaces while hang-drying. Contact with a surface can damage trichomes and break them off of the plant. Depending on environmental conditions, the initial drying process usually takes three to seven days.

Do trichomes wash off?

Those crystals—known as trichomes—are extremely sticky after harvest, so even a drench with water isn't going to dislodge them from the bud itself. That said, anything else holding on for the ride, such as unwanted critters and dirt/dust, will get washed off with no trouble.