I keep the greenhouse around 35-40 degrees during the depth of winter, and days at 85 degrees. Ventilation through the greenhouse and air circulation within the greenhouse are important during the cloudy, cool, damp days from mid December through late February, when mold (botrytis and black leg) are at their worst. Before and after the blahs, keep the greenhouse around 45 for a low and no hotter than 90 degrees. Remember that growth of plants depends on maintaining the correct ratio of heat to total daily sunlight to watering and fertility.

I use a propagating mat kept at 75-80 degrees with a soil thermostat. As long as the rooting zone stays warm, there should be no problems. Use cuttings from robustly growing but not dormant plants, and keep the rooting medium damp, not wet. I use fine vermiculite, but perlite, sand, and mixes will work. The sand should be a washed builder's sand (no fines or clay), used for making concrete. Beach sand is a no-no. The medium should be sterile.

On the mats, I use what are called pen packs, which are solid PVC baby flats about 2" high, 6" wide, and 4" deep. If I have a flat going bad, or need to pluck it out for potting up, the whole unit comes out. You can root rows and columns of plants up to 4x6 or 5x7 in these baby flats.

If there is a breakout of black leg on the mat, remove the infected baby flats and wash off the mats with some dilute clorox. Make sure the mats drain off (no puddles), and keep the new flats on the highest parts of the mats. That way, infected drainage and leaf drops drain away from your better flats. Watch out for mealy bugs, white fly, spider mites, and scale. Ants will move all of these critters around.

Use a ground cloth over a layer of crushed rock to keep out weeds, which will hold pests and pathogens.

If you lose heating, have a big sheet of black plastic handy to cover your greenhouse. This will cut heat losses to about one quarter if you have a reasonably tight greenhouse. Pull it over just after the air temps reach freezing. The plastic will glide over much more easily on the ice crystals. Wet plastic sticks and makes covering the greenhouse much more difficult.

Rich thanks for info........BUT
What if I don't have a prop. mat. In the pass I have taken cutttings and use a misting sytem, which comes on every 15 mins..for 1 min To keep cuttings moist. This is done in my shaded GH where the temp around 80. I have had success with this method on other woody ornamentals.
Do I used the misting on the salvia or just keep the soil moist, not so much the foliage?

What would you say is the easy cultivars to propagate? These are a few I was going to try to root,
Guaranitica -Involucrata-Microphylla - Mexicana.

We are still having alot of warm ,dry - days here in the south, in the high 80's!
I'm a little slow sometimes in getting the whole picture!

Thanks for sharing,
Donna

Misting is helpful for woody plants, like you mentioned. I used to have a mister, but have stopped using it, because it was not necessary. As long as the plants are in an active state of growing, the cuttings will root in about 2 weeks. Coolness at night is the main problem, but not when daytime temps are in the 80s.

My mister was based on evaporation. A square of bronze cloth would get weighed dowm by the mist, and when it evaporated, it rose and turned on a mercury switch. Wind flapping around the square was the only problem.