I have only had luck using "firm new growth" no luck using "hard wood" (winter) cuttings. By the way I propagate all my plants "inside"
Best time June/July take a terminal cutting of firm vew growth about 5-6 inches long. apply 0.3% IBA (rooring hormone) stick in well drained soil & Mist.

Here's a little book information:
"Hardwood cuttings have been rooted but percentages (30% on average) have not been good and some cultivars did not respond at all. Mid-winter (February), wound, 0.8% to 2.0% IBA, talc or solution, ground beds or perlite (green-house), root by late May and grow 4 to 6". They can be overwintered and lined out in spring or transplanted. One nursery considered hardwoods as viable alternative to budding and summer rooting but after 3 years testing scrapped the idea and went exclusively to softwood production."

Dirr, Michael A and Heuser, Charles, Jr. ÂThe Reference Manual of Woody Plant Propagation: From Seed to Tissue CultureÂ; (Second Edition 2006); Varsity Press, Inc. ISBN: 0942375092 or ISBN: 13: 978-0-942375-09-1

It is safe for me to assume you do not own a greenhouse? If you don't, you could build a box about two feet tall & wide and four feet across, or a square box 4' across and 2' tall and drape fluorescent lights just above it. Within it you will make a media(soilmix) box for the base at least 8" tall filling it almost to the top and with the rest of the frame, cover all sides with lightweight clear poly only... Lightweight is very important...

Use furring strips with screws to completely seal the entire box. Purchase a dual Humidity/Temperature guage for about 3 bucks and hand it right in the middle. Your ideal humidity should be at 80% or above. You control this by misting the air in the box several times per day (or as often as you can if you don't have someone at home everyday). You'll have to figure out how you can regulate the humidity on your own. Each environment is always Trial and Error until you find a middle-ground. Your basement will be the very best place (if unheated) because temperatures should be a comfy 50 or so degrees F. The alternative is to purchase a Cool Puff Mister ran at certain times of the day with a Digital Timer you plug in along with your mister. Add some PVC Pipe that fits to your cool puff mister and run the pipe into the box via a knife slice in the lightweight poly. The only cool puff mister I've found to have the right fitting for PVC Pipe was a Vicks model

Remember, you can use this year round indoors for softwood, semi-hardwood, or, hardwood-cuttings. You will know if your humidity is set right when you see moisture and not droplets on the cuttings. A general great all purpose media mix is 4 parts perlite to 1 part Spaghnum.

Add heat mats below the media and you're really running a strong propagation chamber. Refresh the air in the box every few days and if conditions are favorable where you can just drape the poly on the front opening, there's no need to seal up the front........

All that jargon above about IBA - purchase a good product such as either Clonex or Clonex Red or Dip n' Grow.

Best of luck to you.

Dax

Information above based on Cornus florida, Cornus kousa, Cornus officinalis, and Cornus walteri. The most-difficult of all the flowering dogwoods to root.

Take care,

Dax

One last thing and it's Wheel of Fortune time...

Keep your fluorescent lights about 2-3" above your frame. You want the lights close. They don't give off much heat and they need to be as close to the plants as possible. You can run the lights 16 hours a day.

Dax