I cut off most of the stalks, usually leave an inch or so, that's just my preference. It sounds like some leave them on.

Stalks too.

I trim about an inch off the bottom and then used the rest. I would wash and let dry, place ends in a glass and cover with a plastic bag with holes in the top in the refrigerator and it lasts for over 5 days, changing the water every few days. For frozen divide up and wrap in paper towels, then a plastic bag. For freezing, divide in bunches using 1/2 bunch portions. Making the smoothie with frozen, I would break the 1/2 bunch in half, by hand, it snaps and place in blender with other ingredients. I was one of the many that cilantro worked for. I first who learned about cilantro as a heavy metal detox on this site as I had been blogging here for about a year then in mid Feb 2019 Kimass1 shared her information about cilantro helping with GD and I am very grateful for her posting. I still follow this this blog occasionally and have never read where any other form of cilantro other then fresh or frozen benefited anyone. Some mention being too lazy to bother with it preferring capsules or drops, I figure they are the lucky ones because they must not have been suffering as much as I used to. Have I missed something, is there one testimonial on this site where the drops or capsules helped anyone?
Follow up now after being clear for over 1 1/2 years- I just was outside gardening in 90% degree weather, dripping with sweat when I came in and sure I was flushed and hot but my skin doesn't even sting from the sweat. I'm no longer concerned about triggering activity. Even after my visual symptom's abated it took over a year for my skin to become less sensitive to touch or sweat. I know we have lost the collagen connections in our torso skin cells damaged by GD so I have continued taking collagen protein in a smoothie without cilantro and also I take silica daily. If it comes back I will definitely go to the trouble of making the fresh or frozen cilantro smoothies to begin this heavy metal detox again. I do eat deep water fish every few weeks and shellfish- all loaded with heavy metals. For those questioning if it is worth the effort, it works for about 50% of us that do this. Within a month I began to believe I was starting to go into remission, it still took months for this to happen, so don't give up too soon. Sadly it doesn't work for all of us. We do have commonality's like sun exposure and other factors but GD must have different root causes because the same treatment doesn't work for us. Yet we have no other option. I have never read where anyone was ever put in remission by any other treatment. Most us, like me had similar break out patterns. The first outbreak the longest and most severe with itching and pain and for me it covered my entire upper front torso and back torso and then dormant period, then another active period with the front not as active. Still it was miserable. For me it was 1 year initially, then 6 months of activity and then 6 months of remission, yet always a hold over of inactive scabs and always sensitivity and the feeling that little tiny bumps were under my back torso skin if pressed upon during the dormant period.
Best wishes to all of us who are fighting this battle.