80% to 100%, not higher than 100% if you will. If you have the rh at 90% I personally would watch them very carefully for the 1st signs of harmful mold, mildew, and fungus and take immediate action. While my clones sit in an "Aeroponic", not hydroponic but
EZ-Clone Machine I like to put a small oscillating fan on low to aid in air circulation in order to not stagnate the stratified air. Good air circulation/ ventilation are the key to maintaining a proper level of temp. & humidity, that's very important!! I use either
EZ-Clone rooting gel or I prefer "
Clonex".
Clonex is the ultimate, superior ingredient and root hormone packed with all kinds of good stuff. It's a gel so it seals the cutting immediately when dipped into the gel.
Clonex Is very, very reliable and considered the rolls-royce among root hormone powders and gels. Get some- I believe it's cheaper then the
EZ-Clone gel solution in fact. Use humidifiers if you have to to enhance the ambient airs RH%. Space out the cuttings/clones for vegetative cycle before and flowering so they don't compete for each other. I also like "Woods" foliar spray made to combat severe drought and dehdration during the shockin taking a clone/cutting.