Potato shrubs are perennials that belong to the solanum or nightshade genus of plants. All potato plants produce blooms and many species also produce edible tuberous roots that we know as the vegetable potato. Potato plants tend to grow rapidly and adopt a shrubby form with either a sprawling or vining habit. Ornamental species grown for their bloom and foliage can easily tolerate trimming into smaller or simply tidier forms, as needed to suit your garden style or space constraints.
Prune away dead leaves, spent flower heads, damaged vines or any disease that may be visible regularly throughout the growing season to keep the potato shrub neat looking and healthy. Sever at the point of healthy tissue and compost or throw away the clippings along with any debris that has fallen to the soil below.
Create a tree form out of your potato shrub by removing the side stems that emanate from the lower 1/3 to 1/2 of the main stem or trunk. Sever the side stems or branches cleanly, flush with or just 1/8 inch outside of where the two stems meet to prevent gouging into the main stem.
Reduce the height and spread of your potato shrub by pruning back the tips of the stems and vines. Conduct this more significant type of pruning in the late spring or summer to resize or rejuvenate the shrub and encourage new compact growth. Remove up to but no more than 2/3 of the shrub's volume in any pruning session. Cut stem by stem or use long-blade shears as desired.
Cut back the shrub to the ground in late fall or early spring in cool climates where the top foliage dies back each year with heavy frost. Leave at least 2 inches of the main stem above the soil line and remove all other dead or damaged plant material, composting or discarding it.