Gardening Q&A: What should I NOT plant in Beaufort County?

By choosing plants wisely and making summer bulbs an integral part of your landscape, you can create a healthy and colorful summer garden.

Can you provide some general guidelines on what not to plant here? I’ve experienced disappointment that some of the standbys I counted on in my North Carolina garden do not seem to perform well here. (Valerie M., HHI)

I certainly sympathize with frustration over which plants thrive here in USDA Zone 9a and which survive, sometimes barely.

Don’t plant anything without having first checked the plant label for growing zones. I steer clear of any plants which indicate that the highest-numbered zone is 8. Many of those plants will perform well from Columbia northward, but will languish in the Lowcountry. I’ll take a chance if I see one of those plants growing well locally. Even those plants which list zone 9 are by no means a sure thing here.

This zone map was put together by the U.S. Department of Agriculture decades ago. However, the zones are based upon a ten-year monitoring of the average annual extreme minimum temperature at which a plant survives; not at which the plant thrives.

The American Horticultural Society also put together a zone map; however, theirs is a heat zone map. The AHS map works as a counterbalance to the other. For instance, in the USDA map, zone 8 plants exist in South Carolina and in Seattle. Common sense tells even those who are somewhat geographically-challenged that successful plants here are not likely to perform as well in Seattle and vice-versa. Nevertheless, most growers only provide the USDA zones on their merchandise, not both. Consider looking at both maps, available online, as you consider what to plant.

Can you recommend some bulbs that are reliable summer bloomers in this area? (Kathy W., HHI)

Summer bulbs (technically, rhizomes, corms, and tubers, as well as true bulbs) which originate in tropical or subtropical climates and perform well in the Lowcountry include:

Caladium: Although not providing a flower display, caladiums provide a color knockout because of their incredible foliage. Some cultivars are labeled as tolerating a lot of sun; otherwise, plant them in a shady area that needs some bright highlights. They benefit from regular irrigation, but do not like bog-like conditions.

Caladium bulbs have a knobby top side and a smooth bottom side. Growth and display of the beautiful leaves improve with a dose of liquid fertilizer every ten days or so from May through September. Most caladiums will return in succeeding years here. Because they don’t appear until late spring, remember where you planted them to avoid digging them up inadvertently.

Crinum: Crinum lilies can be planted as bulbs or purchased in pots from nurseries. Space the plants 4-6 feet apart. At maturity they reach 3 to 5 feet tall and wide and frequently live for many decades. Dr. Jerry Parsons, retired professor and horticulturist extension agent, says that “Crinums (pronounced CRY-nums) are to the South what peonies are to the North, big bold perennials with wonderful flowers for cutting.” The large, often fragrant, lily-like flowers occur in clusters on stalks about three feet tall in late summer. Crinums are available in solid green and burgundy leaved varieties. Blossom colors include solid white, striped burgundy/white, and pink. The coarse, draping foliage may appear unkempt, at which time the plant can be trimmed by removing bottom leaves for a tidier appearance. They thrive in summer heat and like sun and water, but the soil should drain well. Crinums are not true lilies; they are actually in the Amaryllis family.

Gladiolas: Glads falls in and out of fashion. They are available in almost unlimited color combinations, in both miniature and tall sizes, and they are sun lovers. Glads appreciate a regular watering schedule in soil which drains quickly. Add organic compost, ground bark or peat moss to the soil if drainage is a problem. Individual plants have a short blooming cycle, about two and a half weeks; therefore, gardeners frequently plant bulbs at two-week intervals to extend the blooming season. If the bulbs you purchase are tall growers, expect that you will need to stake them. Caution: overhead watering will sometimes spot the blossoms.

This story was originally published May 15, 2017 at 6:19 AM with the headline "Gardening Q&A: What should I NOT plant in Beaufort County?."