If You Can't Stand the Heat, Get Out of the Garden

If You Can't Stand the Heat, Get Out of the Garden

Gardening with Sun Loving Perennials

By Published August 13, 1994 Updated May 24, 2022

Shop for North Carolina Native Plants at Plant Delights Nursery

Do you find it curious that North Carolina has the reputation in most gardening circles as the land of azaleas and camellias? Folks travel from destinations around the country to view the famous 'Southern Spring'.

What I find interesting is that none of the plants that we are known for, with the exception of our dogwoods, are native in our area. Our reputation began to develop after an influx of plants, mostly from Japan and China that began to fascinate American gardeners, especially in the south. I guess the old saying "Familiarity Breeds Contempt", carries over to our gardening habits. The only problem is that most gardeners these days are not even familiar with many of our wonderful native plants.

Since many native plants are flowering now, I thought it would be a good time to highlight some of the really fabulous perennials. Let's begin by realizing that most native perennials perform entirely different in a garden settings, than they do in the woods, or on the roadsides. What often looks scraggly in the wild, or barely alive at 55, will actually make a spectacular garden plant.

I'll begin with one of my favorite group of garden wildflowers, the eupatoriums. The most striking member of the group is Eupatorium fistulosum, or joe pye weed. This giant grower is often found in roadside ditches from the Triangle area west, through the middle of the country.

Eupatorium fistulosum is a spectacular perennial, with the hollow bamboo like stalks rising to 12 feet, in good soil. The stems are topped now, with massive purplish flower clusters. Large clumps may contain up to 50 flower heads, each nearly a foot across.

There are actually several selections of joe pye weed that you may want to search out for your garden. There are a couple of dwarf forms on the market (dwarf is a relative term). Both the variety Eupatorium ‘Gateway' and Eupatorium ‘Selection' are actually Eupatorium purpureum forms that reach only 4-6 feet and have a much darker flower color. Eupatorium ‘Bartered Bride' is a white flowered form, but unfortunately fades too fast to be of much use in a perennial garden.

My favorite joe pye weed story is that of former NC nurserymen, Allen Bush, who when visiting Germany was astounded by the wonderful perennial that he saw in every public garden and park. He then ordered several hundred of these eupatoriums from Germany to propagate and sell, only to find out soon after they arrived that he his property was filled with thousands of the same plant, which were being mowed to the ground along the roadside.

There are a number of other eupatoriums species and subspecies, 52 to be exact that are naturally found in the Carolinas. There are two other species, very similar to Eupatorium fistulosum. Eupatorium purpureum, a mostly west of the piedmont species and Eupatorium maculatum, a mountain species, are very similar except for their solid stems.

The best known eupatorium is one that is known not just for its ornamental potential, but for its ability to reseed. Eupatorium capillifolium, commonly called dog fennel has a reputation that is hard to deny. Anyone who has ever farmed in eastern NC is very familiar with dog fennel, as one of their least favorite weeds. While it is hard for me to admit, since I have weeded more than my fair share, the plant is quite attractive with its lacy foliage, topped by it's white flower heads, appearing soon. A similar species that I have seen with nice reddish stems is Eupatorium compositifolium.

One of my favorites, is the hyssop leaf joe pye weed, Eupatorium hyssopifolium. This four foot tall native has narrow leaves, topped by a giant head of white flowers that are just beginning to open. This is a great textural plant that can be blended well into a perennial border, where a light and airy feel is needed. I have found a wonderfully robust form in a local parking lot that is particularly nice.

Another very different eupatorium is Eupatorium perfoliatum, or boneset. The botanical term perfoliatum, means that the stem runs through the center of the leaf, sort of like you would find with eucalyptus. This unique perennial makes a nice upright clump to 4-6 feet tall, also covered with nice white flower clusters now. As you can tell by the common name boneset, most of the eupatoriums are medicinal plants used herbally to cure a variety of ills.

Eupatorium rugosum has come into the spotlight recently with the splendid selection from Mt. Cuba Center in Pa., called Eupatorium rugosum Chocolate'. This splendid selection has nice purple foliage, topped with white flowers in very late summer.

As with most perennials, joe pye weed dies to the ground in the fall, and resprouts in the spring. The spring growth is so extraordinarily fast, that visitors this spring, have actually claimed to have seen joe pye weed growing. All of the eupatoriums that I have mentioned are clump formers, although in favorable garden conditions, they may seed around the garden. While most eupatoriums prefer moist soils, they will perform very well in dry gardens, although the height may be reduced slightly.

Another of my favorite groups of natives are the vernonias, or iron weeds. It seems that the sole purpose of these plants are to remain alive long enough to be mowed off by the Department of Transportation mowing crews. This is really a shame, as this is another of our very spectacular native plants.

The most common form is Vernonia noveboracensis, often called New York ironweed. This robust grower to 5-7 feet comes into full flower now with dramatic heads of vivid dark purple flowers. Each clump can become quite large, so give this one room to grow.

I am currently growing nine different vernonias, each of which is spectacular in its own right. Vernonia arkansana is probably the showiest of the species, with literally 50+ flower heads per clump. The form of Vernonia altissima that I have is an awesome specimen. The reddish stems on this very vertical species are topped in truly wonderful heads of brilliant purple flowers.

If you are looking for something smaller, Vernonia angustifolia, with very narrow leaves give a delicate texture to the perennial garden, along with Vernonia fasciculata and Vernonia missourica are slightly shorter.

I'm in my tall plant phase now, and am very much enjoying Vernonia altissima (syn. Vernonia gigantea). This splendid native reaches 8-10' tall in our garden, and is indeed a spectacular addition to an otherwise flat landscape.

Most vernonias are native in the same habitat as the joe pye weeds...ditches and wet areas. As with the joe pye weeds, they adapt very well to dry garden soils. vernonias are easy to propagate from stem cuttings taken now, or just wait, and they will scatter a few seedlings around your garden.

Not only are vernonias great for the garden, but they are a flower arrangers dream come true. They are wonderful in flower now, or equally as spectacular as dried specimens. I leave my clumps in the garden until early spring to enjoy the great winter structure, and perhaps use a few stems in the house for decoration.

Another group of over looked gems include the amsonias, or blue stars. For the most part, these perennials make medium size clumps that are topped with sky blue flowers in early spring...here's one for you tarheel fans.

Amsonia tabernaemontana is probably the most common species in the state. This blue star has leaves about the size of a weeping willow on a 3 foot tall clump. As I mentioned, spring finds the plant topped with light blue flowers for a month.

Amsonia ciliata is a slightly narrower leaf species, that I enjoy in my garden. The lacier texture mixes well in the perennial border. One of the virtually unknown, and difficult to find gems is Amsonia ciliata var. filifolia 'Georgia Pancake'. The foliage on this low ground cover spreading form is incredibly lacy. Here is a sandhills native that truly deserves wide spread use.

My favorite species has got to be Amsonia hubrichtii. This southeast native was introduced to cultivation by Woodlanders Nursery in Aiken SC (which has also been responsible for many of the other wonderful natives mentioned). This narrow leaf amsonia makes a typical size clump to 3 feet with a similar spread. As with the rest of the amsonias, the clump is topped with a very pale blue flower clusters in early spring.

In addition to the flowers, the foliage of amsonias make a great addition to the border with their lacy texture throughout the season. As a general rule, amsonias are full sun perennials then prefer sunny hot dry sites, although they will perform well, with a few less flowers in filtered shade.

Butterfly weed or asclepias is a plant that anyone who has taken a summer drive through the country side has seen. There is little else in the plant world that can equal the brilliant orange flowers of our native Asclepias tuberosa.

Since many of you have probably tried to dig butterfly weeds, you will also realize that it prefers not to be transplanted from the wild. A. tuberosa is a tough plant, however, and will tolerate even the driest and hottest of conditions, and keep on flowering. Occasionally color variants can be found in the range of yellow and red, although these are rather rare.

Another Asclepias that is overlooked as a garden plant is Asclepias incarnata or swamp milkweed. With a name like swamp milkweed, it doesn't sound appealing, but that is far from true. This 3' tall native is smothered most of the summer with clusters of mauve pink flowers. Asclepias incarnata is equally at home in regular garden conditions, in addition to being quite happy in a swamp.

Other wonderful native Asclepias include Asclepias syriaca, the common milkweed and Ascelpias verticillata, the narrow leaf milkweed. All are great summer flowers, as are most of the twenty species of Asclepias native to the Carolinas. I've grown ten native species from seed, and will report their performance later.

One of the most commonly recognized group of native summer flowering perennials are the rudbeckias, or black eyed susans. It seems that everyone who grows perennials, has tried one of the Rudbeckia fulgida forms called Rudbeckia Goldsturm' (Gold Storm). This commonly grown seed strain is little more than our native Rudbeckia fulgida v. sullivantii. It's amazing how this gem has found its way into gardens around the world...long before it every became popular in its own backyard.

Another equally as wonderful, but little used gem is the native Rudbeckia triloba. With hundreds of flowers, similar but slightly smaller than Rudbeckia Goldsturm', this rudbeckias gets taller, and is easier to blend into a border.

By far, the most spectacular native black eyed susan is Rudbeckia maxima. Native to the Mississippi River region, the foliage of this rudbeckia looks exactly like collards...large blue waxy leaves. In late spring, the base gives rise to black eyed susan flowers on seven foot tall stalks. After the initial flowering, the stalks can be cut to the ground to produce a second flowering.

A common native, and a true star in my garden now, is Rudbeckia laciniata. There are several varieties of this native that you are likely to find in your local garden center...most selected again in Europe. My favorite is Rudbeckia laciniata Sun Glow, a gorgeous double yellow. Rudbeckia laciniata can get quite tall, often to 6-7 feet, and makes a large clump, so place it accordingly in the garden.

If you like tall, then you are going to love Rudbeckia nitida. This native resembles a steroid induced black eyed susan. In reality, it is a yellow eyed susan, to 6-8 feet, but sturdy without staking. A good selection to look for is Rudbeckia nitida Herbstonne'.

One of my favorites is the midwestern black eyed susan, Rudbeckia subtomentosa. This native grows to 5-6 feet, and is a wonderful subject to blend into a large perennial border. Our patch is still in full flower after a month of heat and humidity.

If you plant black eyed susans and the plants fail to return, except for a bevy of seedling, you are probably growing the native Rudbeckia hirta or one of its many forms. While occasional plants will survive, they usually act as annuals. This is a good rudbeckia for almost instant flowers, that will persist through the summer.

A first cousin to the black eyed susans are the purple coneflowers or echinacea. Separated at birth by botanists, and to a lesser extent by flower color, there are a lot of similarities. Most gardeners have grown some form of the common purple coneflower Echinacea purpurea. In fact one of the many selections of echinacea, Echinacea ‘Magnus' has been chosen by the Perennial Plant Association as their 1998 Perennial Plant of the Year...a nice honor for a native plant.

This spring and summer flowering native usually reaches 12-24" in garden conditions with flowers of pinkish purple. Purple coneflowers seed occasionally through the garden, and are always welcomed by the flower arranger in the family.

There are a number of narrow petal coneflowers, whose purple petals are much narrower, giving an entirely different look to these garden perennials. Some species with this characteristics include Echinacea pallida, Echinacea angustifolia, Echinacea tennesseensis, and the endangered Echinacea laevigata.

If you really want to dazzle your neighbors, look for plants of the lanky Echinacea paradoxa. This is a real paradox, being the only echinacea with yellow flowers.

One of the most popular, thanks to the work of Edith Eddleman in the NCSU Arboretum perennial border, is Helianthus angustifolia. Often dubbed the swamp sunflower, it is equally happy in swamps or in a typical garden environment. Helianthus angustifolia gets quite large, often to 8 feet by the time it produces its large clusters of yellow flowers in late summer and early fall. I always like to cut these back to a couple of feet in mid summer...works great for height control without affecting flowering time. 

A more manageable, but virtually unknown native is Helianthus atrorubens. I saw my first plant on the roadside in Raleigh, where I was so struck that I had to pull over to the side. Cuttings, which rooted easily allowed me to try this gem in my garden. It appears to be one of those perennials that is so good, it must have just got overlooked.

A fun native to blend with the likes of echinaceas and rudbeckias is Tovara virginiana (syn. Polygonum virginiana) or painters palette. There is a unique selection of this native, Tovara 'Painters Palette' has 12-20" tall stalks of green, black, and white patterned leaves. During the summer, the plants are topped with stalks of tiny reddish flowers that just beg to be blended into the perennial garden.

Another exciting, but overlooked group of garden plants are the liatris or blazing stars. As you drive along the highways, the small patches of purple are probably liatris. Liatris has been thoroughly hybridized, thanks in part to the florist industry that has taken a fancy to these plants. 

While there are fourteen species native to the carolinas, there are two that stand out for garden use. The finest of the blazing stars is Liatris microcephela. This liatris with very narrow leafs also has a wonderful branching habit at the base. The stalks that arise to 3' are clothed in bright lavender flowers.

The other unique liatris is Liatris elegans. Each plant does not make an impact, but a drift of these is quite wonderful. The unique aspect of this liatris it the color of a lavender grey...a far cry from the typical color of liatris.

The final group of plants that I want to visit today are the lobelias or cardinal flower. The common name came from the species Lobelia cardinalis, whose stalks of brilliant red are blazing in the garden now. Lobelias overwinter as a flat green rosette (sort of like a plant cow chip), which must remain uncovered during the winter. In spring the rosette begins to expand, resulting in several stalks of red flowers through the summer and often into the fall. 

The other common species is Lobelia siphilitica, the great blue lobelia. Lobelia siphilitica is not a graceful as L. cardinalis, but it makes up the difference by being unbelievably tough. The flowers of either blue or white occur on 15-30" spikes during the summer also.

Thanks to the work of breeders such as our local Thurman Maness, who has combined these two species into a number of wonderful hybrids, we are continuing to expand the usefulness of many of our wonderful native plant species. In many cases breeding, or simply selecting and propagating a particularly nice form of a native may be all it takes for a plant to get the recognition that it deserves.

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