Question
I pruned a rhododendron back to a manageable size near our house about a month ago and some of the branches would be very nice sized plants if I can root them.  Is this possible? They have been stored in a big bucket of water outside and they are still growing.

Answer
Hi Judy,
Thanx for your question.  Yes, rooting of cuttings is very doable.  I've attached a nice reference from the American Rhododendron Society on cuttings. I've rooted cuttings before and it is not difficult.  Just have to be diligent and patient.  The key is, use rooting hormone.  I use sand as my medium.  Just buy a sack of play sand.  Be careful gathering sand from a river or construction site as there may be harsh chemicals and unsanitary matter in it.  Keep the sand uniformly moist but not waterlogged.  Keep the medium warm.  At least 70篎/21篊 but not much warmer.  I put a clear plastic bag over the pot which helps keep in moisture.  Cuttings greatly benifit from misting or high humidity.  Keep out of direct sunlight.  I don't recommend putting on a window sill as this can "cook" the cuttings.  Put the container in a place that gets either diffused sunlight or artificial bright light.  It will take several months for the cuttings to root.  If the cuttings start budding, that doesn't mean rooting is sufficient.  After a couple months, check gently around the cuttings.  If there is substantial rooting, gently remove the cuttings and pot up in separate pots.  You will have to acclimate the cuttings after they have grown sufficiently in the pots (several months).  Put the pots in the shade first, after any danger of frost, for about 10 days and then plant in desire locations.  I hope this helps.
Tom

https://www.rhododendron.org/v48n4p201.htm