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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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