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2002: The Year of the Vinca

The National Garden Bureau Celebrates 2002 as the Year of the Vinca

Clear flower colors and glossy green leaves make vinca indispensable for season-long interest in the garden and in containers. Add practically no maintenance to these drought tolerant plants and you have a winning combination. Native to Madagascar, vinca acts as an annual in most regions of North America. It blooms beautifully from the first warm days of late spring to the first frost in fall. In the southern climates, it is at home enough to naturalize in many areas. The National Garden Bureau designates 2002 as the 'Year of the Vinca' since the plants provide so much garden color with little care.

What's in a Name? Transplanting
History, Past and Present Growing in the Garden
Starting From Seed Indoors Growing in Containers
Selecting Plants Diseases and Pests


WHAT'S IN A NAME?

Vinca is one of the best examples of why you need to know botanical names. Known variously as vinca, periwinkle, and Madagascar periwinkle, summer-flowering vinca is Catharanthus. It is easily confused with Vinca minor and Vinca major. All of them are members of the dogbane family, Apocynaceae. Catharanthus likes the exact opposite conditions of its cousins, which are also called vinca. Catharanthus prefers sunny, hot situations and blooms all summer until frost. The cousins, Vinca minor and Vinca major, are evergreen vining ground cover plants for shade that produce lovely, generally blue, flowers in spring; they are propagated from cuttings not seed. Another cousin, called vinca vine (Vinca major), is a trailing vine with soft green leaves variegated whitish-yellow; it is popular for use in containers, window boxes, and hanging baskets.

Why the name confusion? The plant botanists who first observed Catharanthus noticed that the flower closely resembled Vinca minor, and it does superficially. They named it Vinca rosea. By the time botanists realized the differences between the plants, the name vinca had become too common to change. The botanical name for the summer flowering vinca, however, underwent a few changes from Lochnera to Ammocallis until it was finally classified as Catharanthus. The species name, C. roseus, which means rose-colored, changed only from the feminine rosea to the masculine roseus to match the gender of the Latin name of the genus. The genus name, Catharanthus, translates as "pure flower." Most modern cultivars are a consequence of hybrids made between C. roseus and other Catharanthus species.

All vinca flowers are simple: they are single, never double. Most modern varieties have overlapping petals. (The species, C. roseus, is rosy pink with a small mauve "eye" at the center; there is also a white form.) Thanks to extensive breeding, the color range of vinca now includes pink, deep rose, red, scarlet (the newest being 'Jaio Scarlet Eye,' an All-America Selections winner for 2002), white with red eye, lavender blue with white eye, peach, apricot, orchid, raspberry, burgundy, and many other shades. The 'Stardust' series contains flowers with star-shaped white centers; 'Stardust Orchid' won an AAS award in 2000. Vinca usually grows 8 to 18 inches tall with a 1-foot spread, although there are trailing types that spread to 2 feet.

HISTORY, PAST AND PRESENT

Gardeners and herbalists cultivated vinca for centuries in Europe, India, China, and America. In Europe and elsewhere it was used, along with its cousins, to treat all kinds of diseases, from coughs and sore throats to eye and lung infections. Most interesting was its folk use in treating diabetes. In the 20th century, researchers discovered the plant contains dozens of alkaloids: some of them lower blood sugar levels (providing folk remedies with scientific provenance) and blood pressure. In the 1950's, they discovered two alkaloids that are the source of anticancer drugs. Leave the use of vinca in medicine to the professionals and enjoy them in their modern forms in your gardens for their beauty.

As far back as the 1920's, hybridizers worked with selections of the species, C. roseus, to come up with improved plants. Sakata Seed Corporation, a wholesale company headquartered in Yokohama, Japan, offered four varieties of C. roseus in its 1925 catalog: Rose, Alba Okulata, Alba Pura, and Mix.

Through the 1980's, popularity of vinca as a bedding plant was limited because commercial varieties had limited color range: pure pink, rose, white and white with red eye and also poor germination. In the background, however, improved cultivars were pending. In 1976, Ron Parker, at the University of Connecticut, started an interspecific breeding program. He collected seeds of Catharanthus species from professionals and hobby collectors to begin a totally new breeding program. He was looking for new colors, plant habits, freedom of bloom, and improved garden performance.

Meantime, in 1988, two new cultivars with improved germination rates and colors were introduced: 'Grape Cooler' (lavender-pink with rose eye) and 'Peppermint Cooler' (white with red eye). In 1991, the first of Ron Parker's new varieties became available. 'Pretty in White' and 'Parasol' were the result, and they earned All-America Selections awards. They were produced and sold by PanAmerican Seed Co. The same year, Waller Genetics, in California, introduced the new 'Tropicana' series from Parker's breeding program. The plants had new colors with larger flowers and overlapping petals. They were followed in 1993 by more results developed from Parker's germplasm program, the 'Pacifica' series which included the first red-flowered vinca. In subsequent years, additional color breakthroughs came as commercial breeders began to use more of the interspecies cultivars. Bodger Seeds introduced the 'Heatwave' series including new flower colors and PanAmerican Seed introduced the first F1 hybrid vinca, 'Blue Pearl.'

New and improved varieties appear frequently now, including carpet-type plants with trailing habits. The 'Mediterranean' series bred by Waller Genetics are particularly appropriate for baskets.

STARTING FROM SEED INDOORS

Growing vinca from seed is one of those activities that appeal to curious and/or enthusiastic gardeners. Far from being the difficult task it is touted to be, growing from seed simply takes a little more time and effort than buying plants at the garden center. Vinca does not like cold, or even cool, temperatures or an abundance of moisture; both conditions existing outdoors in spring. Starting indoors, you control the environment.

  • Plan to sow the seeds 10 to 12 weeks before your average last frost in spring.
  • Fill a shallow container or a flat with individual cells with a seed-starting mix. Moisten the mix and let it drain.
  • Sow seeds in rows in the container or 3 to 4 seeds per cell. Cover the seeds completely with 1/4 inch of the mix; press the mix down lightly and spritz the surface with water to moisten it and settle the seeds. Vinca requires total darkness to germinate; if light reaches the seeds, fewer of them will germinate. Cover the container with a sheet of black plastic or slip it inside a black plastic trash bag (instead of the usual clear plastic bag you use for other seeds, such as petunias and geraniums). If you can, set the container on a heating cable or mat to maintain a temperature of 77 degrees F (25 degrees C) in the media.
  • Seeds will germinate in one to two weeks. Immediately remove the plastic cover and place the container in your sunniest window or in a fluorescent-light garden. Grow the plants at 70 degrees F or higher.
  • Don't overwater or overfeed the seedlings. Remember that vinca is drought tolerant. Water when the planting medium dries, but before the plants wilt. Fertilize about 10 days after the seeds have germinated. Use a water-soluble fertilizer that is low in phosphorus (the second number on a plant food label: 10-4-3, for example) and preferably obtains most of its nitrogen (the first number on the label) from a source other than ammonium nitrate.
  • When seedlings are about 2 inches tall, snip off all but the strongest plant in each cell at soil level. Space plants in flats about 2 inches apart. Transplant them to individual 2-1/2-inch pots when they reach about 3 inches tall and have at least three to four true leaves. Provide good air circulation by not overcrowding the plants.
  • Provide high light levels, a southern window for example, to avoid "stretched" or leggy plants.
  • Fertilize again in two weeks.
  • Keep the plants indoors until soil and air temperatures outdoors are consistently above 65 degrees F.
  • Vinca branches naturally so you do not need to pinch out the growing tips to create a full, bushy plant.

SELECTING PLANTS AT THE GARDEN CENTER

Most gardeners opt to purchase vinca plants someone else started from seed. Garden centers and nurseries carry an abundance of vinca because it is so popular for edging gardens and growing in containers.

Look for plants with bright green foliage. Avoid any with yellowed leaves on the upper or lower parts of the plant; they indicate potential problems with root rot. Pass up leggy plants in favor of more compact, well-branched specimens.

Most vinca will be in flower when you buy them, so you can select by color. If you find plants in bud, look at the variety name. Variety names are usually, but not always, a good indication of the plant's bloom color. 'Jaio Scarlet Eye' (from Dai-Ichi Seed) is rose-scarlet with a small white eye. 'Peppermint Cooler,' for another example, produces white flowers with a red eye, and, as the name implies, is one series that performs better than most under cool, wet conditions. 'Blue Pearl,' the first F1 hybrid vinca, bears very pale blue flowers.

Although most vincas grow between 1 and 1-1/2 feet tall, you can find dwarf or more compact varieties. One of the 'Heatwave' varieties from Bodger Seeds, 'Heatwave Pink,' has a very dwarf habit.

TRANSPLANTING

In most regions, plant vinca in full sun. In hot regions of the south and southwest, the plants appreciate some protection from midday sun. Plant only when the temperatures have warmed up in late spring. If you set the plants out too early, you risk losing them or having poor growth and few flowers. The deep green, glossy foliage of vinca forms an attractive edging even when the plants are not in bloom.

Prepare the soil. Vinca prefers a slightly acid soil with a pH of 6 to 6.5. It needs a soil that drains well, but not one that is particularly rich or fertile. Dig the bed to a depth of about 6 inches and incorporate a one-inch layer of compost or dried manure before planting. If you plant in an existing flower border, the amendments you originally added there should suffice.

Transplant. Pick a cloudy, calm day to transplant, whether you plant homegrown or store-bought seedlings. Use a trowel to dig a hole, unpot the plant, and set it in the ground at the same level (not deeper) it was growing in the pot. Firm the soil around the root ball. Space plants 8 to 12 inches apart for a border edging, 6 to 8 inches apart to quickly cover an area as a ground cover. Be careful, though, with close spacing because lack of air circulation creates the potential for problems later on. Set naturally trailing vincas, such as the 'Mediterranean' series and 'Cascade Appleblossom,' 12 to 14 inches apart. When you finish setting all the plants in, water well at soil level; try not to wet the plants' foliage.

GROWING IN THE GARDEN

Use vinca to edge a border of annual or perennial flowers, to weave color through a bed, or in container gardens (see below). Even the most vibrant flower colors tend to be soft in hue so they never overpower other flowers. The appealing central eye on each bloom adds a bright, cheery note to any garden. When not in bloom (which is seldom) the plants offer a neat, green edge around the perimeter of a garden or along a walk or driveway. Planted as a ground cover, they fill in empty spaces within a border.

Mulch the soil around the plants, not only to help the soil conserve moisture and to deter weeds but also to protect the plants during inordinately rainy weather. A layer of mulch, such as bark chips, helps minimize splashing, which can transfer fungal spores from soil to leaves.

Fertilize monthly with a granular or water-soluble fertilizer.

Water infrequently if at all when the plants have become established in the garden.

In the midst of a hot summer drought, the leaves may curl up during the day. Don't worry. They will unfurl when evening arrives with its touch of dew.

In many areas of the south, the plants self-seed, but they are not invasive.

You do not need to groom vinca by removing spent blooms; they drop off. Plants stay neat-looking all season.


PRETTY IN CONTAINERS

Being drought tolerant, vincas do particularly well in containers, where the soil can dry out quickly. That is not the main reason to use them, however. Their medium height and all-season bloom help you create beautiful combinations and pots of color. Mix them with blue or red salvias, geraniums, zinnias (especially Z. angustifolia), French marigolds, or petunias. Edge a large container of coreopsis or daylilies (particularly Hemerocallis 'Stella d'Oro') with white-, apricot-, or cherry-flowered vinca. Blend a series of vinca colors in one pot and edge the planting with some sweet alyssum. Fill a hanging basket with trailing vincas in shades of white, apricot, pink, or rose.

Planting. Select a container with drainage holes in the bottom or sides so the soil does not become waterlogged. Use a packaged potting mix or a soilless mix; do not use garden soil. Garden soil often contains weed seeds and is quite heavy when wet. If you plan to move the container around or you plant a window box for a sill or deck railing, consider using a soilless mix, which is lightweight. If you want to skip fertilizing the plants during the season, incorporate a controlled-release fertilizer in the mix before planting, though not really necessary with vinca.

Before unpotting the plants, set them on top of the mix in the container and rearrange them until you like the design. Then, unpot and place the plants in the mix at the same level they were growing originally. Water the planting well.

Check the soil in the containers frequently in very hot weather and water as needed. You can wait to water vinca until the leaves just begin to wilt, but if you plant them with other flowers and vines, figure to water before they reach that stage.

Fertilize monthly with a water-soluble plant food, if you did not use a controlled-release fertilizer at planting time.

DISEASES AND PESTS

Water correctly to prevent most of the fungal diseases that can cause problems for vinca: Root rot, botrytis, alternaria leaf spot, and aerial phytophthora. The latter is the most common fungus you may find in the garden and the best technique for preventing it is watering with drip irrigation. At the very least, direct water from the hose onto the soil or mulch, not on the plants themselves. Overhead watering splashes the fungal spores onto the leaves and stems. Because vinca is very drought tolerant, you can water infrequently. In fact, unless you encounter a severe drought, you may not need to provide extra water after the plants get established in the garden.

Pests seldom bother vinca, although you may occasionally find aphids on the plants. Wash them off with hard spray of water from the garden hose. Larger pests such as rabbits and deer avoid eating vinca. In deer infested areas, vincas are highly recommended plants that will provide summer color.

Information and Photograph courtesy of National Garden Bureau.

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Date last revised: 01/05/2010