No they have to be good and dry. First time I tried it using a branch I cut off to sample and the leaves were still dampish and I had to hand trim. Two days later I was able to trim each branch in about 2min! Gave each bud a good brushing (down strokes) then hand trimmed anything leftover which wasn’t much, small stem here and there. Your friend will enjoy it. I’m no salesman, I just know how bad trimming can be and I don’t have arthritis so that has to be much worse. But yea, I did 2 plants in a 50min TWD episode, did the other 4 the next night in no time. My eyes didn’t even get tired