Q.: I saw a beautiful bush that I want to plant. It has snowball-shaped white flowers and grows in the sun. I think is it a snowball bush, but I am not sure. Can you help?

A.: One reason the scientific names of plants are so important is to be able to purchase the specific plant we want. We don’t have to be able to pronounce the Latin names of plants, but we must communicate the name to the seller to get the plant desired. Several different plants may have the same common name, and that is confusing. Snowball bush is one of the common names that people have given to plants having white flowers resembling a snowball shape. There are two shrubs that I think of based on your description, so how do you find out which is the one you want to plant? I believe that you may be describing either a Chinese Snowball viburnum or a Pee Gee hydrangea. I hope the following comparisons might help you decide which it might be.

When does the shrub bloom? Chinese snowball, Viburnum macrocephalum, blooms in the spring and because of our long growing season, it may bloom again in the fall. Pee Gee Hydrangea, Paniculata grandiflora, blooms from mid-summer to fall.

What about the color of the bloom? Chinese snowball blooms are first lime green, changing to snow white. Pee Gee hydrangea blooms begin white, later turn lime green, then in the fall develop a pink blush as cool weather touches them.

How about the flowers? Chinese snowball and pee gee hydrangea have clusters of sterile flowers that form a large ball. The viburnum has softball size clusters and the hydrangea has larger cone shaped clusters. Neither is fragrant.

What about the foliage? Snowball viburnum is semi-evergreen, which means it keeps its leaves throughout the year unless extreme cold kills them. The hydrangea loses its leaves after the first frost.

In addition, the following may help you in the care of the two shrubs:

Both of the shrubs require full sun, well-drained sites, and prefer acidic soils, but tolerate alkaline soil. Both shrubs should be fertilized at planting and each year after blooming. Container grown shrubs may be planted at any time of the year; however, more watering will be required if you plant them in spring or summer. Fall is the favored time for planting shrubs as it allows the roots to grow, producing a healthier plant in one season. Once the plants are established, they are both fairly drought tolerant.

How are they pruned? Plant guru Michael Dirr recommends hacking the Chinese snowball viburnum back to 2 to 3 feet each year. Pee gee hydrangeas may also be cut to 3 feet every year and they produce plants that at 6 feet tall on one year’s growth. Both shrubs bloom on new growth and seem to have a better shape after pruning.

Both shrubs are beautiful and would make great additions to a yard. Since they bloom at different times of the year, you could plant both and enjoy each one. I hope that you locate the shrub you want.