'Greensleeves' is a full size kousa so the sizes quoted are realistic. 'Wolf Eyes' is a more compact and shrubby form of kousa and generally remains at about half the size of a typical kousa but could get larger.

Just an FYI, but kousa dogwoods generally will develop to be wider than tall over time. I believe it to be more critical to allow for an adequate canopy spread for these trees once mature, rather than for height. Dogwood trees typically react poorly to much pruning so you want to keep that at a minimum.

Yes: 15 ft. from the porch will eventually become too close. Local experience with this particular cultivar not necessary to know this.

Patty, I agree. Not the right tree type to plant 15' from a porch. When you have a few minutes do a general search for....Polly Hill Cornus kousa. Interesting pictures and an introduction to Polly who was the well known hybridizer/specialist introducing new varieties of Cornus kousa through the years. It was Polly who discovered that if a cutting was taken from the very top, upright branch of a Cornus kousa it would mature into a thinner and taller form. However, side shoot cuttings will grow into the familiar, more rounded Cornus kousa shape.

While on the subject I would encourage planting the evergreen types of Cornus kousa. Heavy bloomers into the summer months. Lower branching close to the ground should be encouraged. Great ornamental tree for that 'special spot'.