I really would like to help you so IÂll start off with a frank, but truthful statement. You are wasting your time with all these plants. Most of them can be propagated fairly easily, but at different times, and with different methods. And they will all take much longer than the few weeks you have waited.
Lilac is difficult, or nearly impossible to root from cuttings. They are mostly grown from seed, but small quantities can be propagated from root cuttings with a sprout, or division.
Burning bush is fairly easy with cuttings and layering in the summer, or cuttings in the fall.
Grapes are almost always by dormant cuttings, but they need some cold stratification. The process of taking, handling, and planting the cuttings is very different from what you describe. You will need longer cuttings, deeper media. Blackberries are easiest done with root cuttings, or offset division. Other methods work also, but are much more technical.
You should be able to do any of them without bottom heat.

Here is a suggested place to start. Do a google search on the plant name followed by propagation: IE Grape Propagation, or Lilac Propagation.

Thanks for the info Tom. My research on grapevive propagation mentioned that the ground the cutting is planted in will need to reach 80-85F degrees for the callus to form. After the callus formation roots will develop at lower temps. I've not read anything about stratification of grape cuttings.

I assumed I could force the callus formation for the blackberry, liliac & burning bush the same way.

Should I trim the bottom of my 18" grape cuttings and try again since they are still not callusing? Anyone?

On any of those plants you mentioned, (in our zone) you can take cuttings in the fall, stick them directly into the ground and they will begin to grow the following spring. I think you may be trying too hard, UNLESS you are just wanting to have something to do. If you really want more plants, do the cuttings and immediately stick them in some well-draining spot that is protected from the wind and they WILL root!

Dormant cuttings taken of grape in Dec-Jan ,wrapped in a bundle in a plastic bag, with their bottom ends in moist sphagnum and placed in the crisper drawer of your frige will give almost 100% by spring. As mentioned above just sticking them in the ground will work if they are covered to keep them from dehydrating.

George