No holes to begin with but if you have a lot of condensation then you do want to vent some of the excess moisture. Move the bag or lid enough to create a small opening between the tank/pot and the lid/baggie.

If you propagate outdoors and you live in a humid region you shouldn't even have to use a bag or lid.

hcmcdole..........thank you! I am in nc and it is hot and humid here, I can leave the cover off you say? ok, will try it...just planted 3 cuttings yesterday. they are on my deck hidden under a chair from direct sun. I will remove the cover tomorrow, thing is though, won't I then have to water them? if I leave the cover on, I shouldn't have to water?

Hydrangea from cuttings are so easy you can do it all wrong and still be successful. I just use my regular potting mix, do not tent at all, keep the mix wet, and just wait for the rooting. If I am not careful I end up with more Hydrangeas than I can use, or give away. Al

Calistoga....I remember two years ago doing it and not having a problem. but this year, I am on my third try and the first two times the stems and the leaves turned black and then fell over. I have been using this little greenhouse thingy that I bought 2 years ago in lowes....

Don't use the greenhouse it is too hot this time of year, just keep them in the shade. Al

So all you do is take a cutting and place it in pot with reg potting soil and keep moist?

Yes if outdoors.

Calistoga.........I took the top off last week. they look good. not turning black!!