Flowering Dogwood trees can be easily grown from seed. However 99.9999% of the seedlings that sprout will be Cornus Florida, which is White Flowering Dogwood. It doesn't matter if you collect the seeds from a White Dogwood or a Pink Dogwood, the seedlings are likely to be white.
The only predictable way to grow a Pink Dogwood, Red Dogwood, or one of the beautiful Dogwoods with variegated leaves, is to bud or graft the desired variety onto a White Dogwood seedling. That's why the botanical name for Pink Dogwood is Cornus Florida Rubra. Cornus means Dogwood, Florida indicates White, Rubra indicates Red or Pink. Cornus Florida Rubra indicates Pink Dogwood grown on White Dogwood rootstock.
Between budding and grafting, budding is the most common technique used in the nursery industry. Grafting is usually done in the late winter months when the plants are dormant. When you graft a plant you remove a small branch (4 to 6 inches) from the desired variety, trim the end of the branch to expose the tissue under the bark and then trim a taper on the end. You then trim the seedling in such a way to match and receive the branch you are grafting on to it. Timing, temperature, and humidity are all critical to the success of the procedure, which is usually done in a greenhouse.
Budding is much easier, and does not have to be done in a controlled environment. Most budding is done later in the summer when the bark on the seedling slips easily. That means that when a cut is made in the bark of the seedling it can be easily pulled away from the tissue layer under the bark. This tissue is known as the cambium layer. Here in the north Crabapples and other fruits are usually ready to bud around mid to late July, while Dogwoods are not ready until late August.
Unlike grafting where you use a small branch to attach to the seedling, when you bud you insert a single bud under the bark. Budding is usually done down low on the seedling, very close to the soil. You can bud up higher, but any new growth that appears below that bud must be removed because it will be identical to the rootstock and not the desired variety.
The budding process is quite simple. Just clip a branch from the tree of the desired variety, this is known as a bud stick because it has many buds that can be used for budding. The buds can be found at the base of each leaf. Look closely where the leaf emerges from the branch and you will see a very small bud. In the fall when the tree goes dormant the leaf will fall off, and bud will remain. The following spring the bud will grow into a new branch.
When you slip that bud under the bark of a compatible seedling, it will grow the following spring just as if it were still on the parent plant, with all of the qualities of the desired variety. Almost all fruit bearing and ornamental trees are grown this way.
Just make a "T" shaped cut in the bark of the seedling. A horizontal cut about 1/4" long, with a vertical downward cut about 1/2" long. The two cuts should intersect at the top of the "T". Don't cut into the cambium tissue, just slice the bark and open it up slightly with your knife or razor blade. Now you are ready to remove the bud from the bud stick.
First clip off and discard the leaf from the bud that you are about to remove. When you remove the leaf, leave the stem attached to the bud stick, just remove the leaf itself. The stem makes a nice little handle to hold on to. To remove the bud from the bud stick just cut into the bark and under the bud, it should pop off easily. Again, don't cut into the cambium tissue, but make sure you are under the bark so you don't damage the bud. Along with the bud you will have a small piece of bark shaped like a tiny banana peel, and the stem from the leaf.
Holding the bud by its handle (the stem) slide it into the "T" shaped cut you made on the seedling. Make sure you put it in right side up. The stem and the leaf should protrude through the slit, and the stem should be pointing toward the sky at an angle. Push the bud all the way down into the slit by catching the bark, (not the bud) with the tip of your knife.
Now cut a rubber band so that it is no longer a loop and wrap it around the seedling to close the opening so dirt, water, air, and insects can't get in. Make a wrap below the bud, and a few wraps above the bud. Use a rubber band approx. 1/4" wide, and be careful not to wrap too close to the bud, nor too tight.
You don't want to strangle the seedling, it needs to be healthy and happy so the new bud will bond to the cambium layer. Leave the rubber band on until early spring, at which time you should remove it, and clip off the top of the seedling just above the bud. As the plant comes out of dormancy the bud will begin to grow into a new branch just as if it is still attached to the parent plant, except that now it is going to grow upright and form the stem of a tree.
When this new growth reaches a height of 3 to 4 feet, clip the tip off, this will force it to start putting on lateral branches. Once these lateral branches are 18" long or so, you can remove all the growth from the stem below where the lateral branches start. Now the plant should look like a beautiful little tree. And that makes you the proud parent!
With all of that said, today it is possible to grow Pink Dogwoods by rooting cuttings under intermittent mist, however, it is tricky, and my few attempts have failed. ' Most nurseryman still bud them.