Vegetation within a planned landscape should serve a purpose. The form of such vegetation should be appropriate to such purpose. Trees provide shade. Shrubbery defines space and obscures undesirable scenery. Vines climb fences and other infrastructure. Annual bedding plants provide more seasonal color than most other vegetation. Turf grows into useful lawns. It is helpful to plan accordingly for a landscape.

Turf can not do much more than become useful lawn. It can not provide shade, obscure undesirable scenery, climb fences or provide more seasonal color than green. Nor can trees, shrubbery or vines become useful lawn. Again, each form of vegetation should be appropriate to its particular application.

Trellised rocktrumpet is not shrubbery. Rose periwinkle is not permanent ground cover.

There is so much other vegetation that would have been appropriate to this particular situation. Star jasmine, trailing lantana, trailing rosemary or even the dreaded English ivy would have been better and more permanent ground cover. Dwarf oleander, barberry, arborvitae or even dwarf New Zealand tea tree would have been better shrubbery.

Rose periwinkle is an annual bedding plant. Although it is somewhat pretty now, it will not likely survive through winter. Even if it does, it will not migrate far enough to reliably function as a ground cover.

Trellised rocktrumpet is a small but vigorous vine that will always be reliant on trellises for support. As its cheap trellises decay and deteriorate, it will eventually develop into shabby mounds of tangled vine stems, but will never be able to support itself as high as the new trellises are now. It can reach out to cover some of the ground that will be vacated by the rose periwinkle, but can not reliably function as a ground cover for this much area. It will bloom less if shorn for neatness.