Humidity: You will read again and again that Salvia divinorum loves
humid conditions. This is true to some extent but there is no need to
mollycoddle the plants. A humidity tent might be an idea for young plants
or rooting cuttings, but is something of an overhead (excuse the pun) and I
prefer not to use any special set-up. Cuttings might go well to start with
under some sort of cover or in a propagator, but I think it makes for less hardy
plants in the long run. I simply do mine open to the room environment. Here in Edinburgh, and in the UK generally,
the climate is far from arid. So apart from maybe during particularly parched
weather, when an occasional misting from a hand held spray gun might be
appreciated, plants (and cuttings) should do fine without a tent. They will adjust to the
ambient humidity.
Having said that, if you do have your plants under some kind of humidity
cover and you want to bring them out, then you will need to acclimatise them
gradually. This means exposing them to the ambient conditions for only an hour
or two at a time for a the first few days, then extending this exposure period
over the course of a few weeks. Alternatively, you could gradually adjust the
set up of your tent, leaving it more exposed, with larger and larger gaps in the
sheeting as the days go by. In any case you may lose a few leaves as the plant
'morphs', - producing new (and different looking) leaves that are adapted to the
drier conditions.
Humidity Tents: I have suggested that building a humidity
tent is not really worth the effort because the plants can adapt to lower humidity.
This is of course based on my experience and my local conditions. I have a humidity measurement suggesting that the average ambient level here is
between 40-60%, which is fine. However, going any lower than this for long
period of time might be
pushing the plant beyond its ability to adapt. If your conditions are more
arid you may need to give this more consideration.
A humidity tent can be fashioned simply from some thin clear plastic
sheeting, for example, some packaging from a largish appliance. This is used to shield or enclose the plant. You can
build a frame using bamboo cane. You don't need to totally enclose your
plants in this tent, you don't need 100% humidity. Leave a few ventilation
openings, especially if you're just using the tent as a nursery for young plants
and cuttings and are wanting at some point adapt to your plants to the natural
environment.
A humidity reader to measure the levels is quite helpful, but using
guesswork, common sense, and simply observing how the plants are should do just
as well.