One of the benefits of living in Arkansas is that we can plant and enjoy pansies in the winter landscape.
Pansies are recommended for beginning gardeners. Especially when purchased as bedding plants, pansies are very easy to grow and require only a minimum of care to provide a very long flowering season. Available in a wide variety of individual colors and mixes, pansies can also be started from seed either indoors or directly in the garden.
Pansies are a remarkable winter annual capable of surviving temperatures down to the single digits, freezing solid, then bouncing back with vigor when warm weather returns. Pansies are planted by the millions in Georgia and are one of the top-selling bedding plants for fall landscapes.
Intensive breeding programs provide us with an amazing array of pansy flower colors, ranging from white to rich gold, purple, red, rose, maroon, orange and violet, with many shades in-between. You can also choose from solid colors (called clear-faced pansies) to blotches (having a darker, contrasting center, often referred to as faced pansies) to two-tones and all sorts of color blends and pastel shades. Some varieties have petals with crinkled or ruffled edges. Others have large flowers up to 4 inches in diameter.
The modern pansy, Viola x wittrockiana, is thought to have evolved from Viola tricolor, Johnny Jump-up, a common native of central Europe. The Greeks in the 4th Century B.C. used them as medicinal herbs for curing respiratory problems and colds. By 1850, many pansy strains were available to European gardeners, soon making their way to the North American market. By 1900, pansies were a popular North American annual.
Today, there are more than 300 varieties of pansies, including many hybrids bred for improved heat tolerance, unusual flower colors, larger flower size and plant vigor. Johnny Jump-ups are still popular among landscapers, some of whom prefer them and say they are more cold-hardy than pansies.
The first pansy hybrids with dark central blotches (as opposed to just lines) appeared in 1814, and by 1835, there were 400 named varieties on the market – “beautiful, flat, symmetrical, velvet-like flowers, more than 2 inches in diameter, magnificently and variously colored.” These are the words of Charles Darwin, who took a keen interest in the cross-fertilization of plants. He was working on his theory of natural selection at the time and conducting his own experiments with pansies and other flowers, keeping detailed records of the various traits that arose through many generations.
Large, exotically patterned pansies became all the rage in Europe, where they were displayed at floral exhibitions and painted by the leading artists of the day. But many of these Victorian hothouse oddities proved too temperamental for the average gardener, and it wasn’t long before breeders began working on hardiness as well as color and form. Pansies today, although equally beautiful and variable, are much better suited to the home garden.
Pansy plants are available in a wide variety of containers, from cell packs (36 or 24 plants/tray) to 3-inch and 4-inch pots. Plants in larger pots generally have a larger, more developed root system and are the preferred choice in the professional landscape industry.
Pansy quality at time of purchase is extremely important because it determines to a great extent how the plants will perform in the landscape. Before purchasing plants, make certain they are healthy and free of insects and diseases. The crown of the plant should be compact and have deep green leaves. Avoid purchasing overgrown, leggy plants or plants that are root-bound in their containers. These plants are stressed and will have a difficult time getting established after planting. Look at the roots to make certain they are healthy, showing an abundance of white fibrous roots along the external portion of the root ball.
Like other types of seasonal color, pansies must have well-drained soils and cannot tolerate wet feet. Planting pansies on elevated beds, 6 to 10 inches above the existing grade, will not only assure good drainage but will also improve the visibility of the color display.
If the bed to be planted previously contained summer annuals, remove and discard the old vegetation to avoid carry-over of insects and diseases. Some landscape firms also discard the old mulch to prevent disease carry-over.
Avoid incorporating the old mulch into the bed as an amendment, because micro-organisms in the soil will feed on it and break it down into humus. As they feed on the organic matter, the microorganisms utilize nitrogen in the soil. As a result, nitrogen levels in the soil may be depleted, causing plants to appear anemic and hungry.
When preparing a new bed or revitalizing an existing bed, adding organic materials can improve the soil. Organic amendments improve a soil’s water- and nutrient-holding ability. Compost and composted animal manure are frequently used as amendments. A 25 percent by volume quantity of amendment is recommended for best results; this equals 3 inches of organic matter incorporated into the top 12 inches of soil. Avoid high amounts of organic matter (more than 25 percent by volume); the humic acids and organic salts it releases can cause plant problems.
Once the organic matter is incorporated, take a soil sample for pH and nutrient testing. Soil testing is available through your local county extension office. Pansies prefer a pH in the range of 5.4 to 5.8. A soil pH above 5.8 can result in boron and iron deficiencies; therefore, avoid liming pansy beds out of habit, unless the soil test indicates a need for lime.
Fertilization requirements of pansies differ from other types of seasonal color. Avoid using fertilizers containing high amounts of slow-release ammoniacal nitrogen. These fertilizers are commonly used on summer annuals but are not recommended for pansies.
High rates of ammoniacal nitrogen can cause pansy stems to stretch and become succulent during warm fall weather, which weakens plants and makes them more susceptible to winter injury. Ammoniacal nitrogen also is slow to be absorbed by the plants during the winter months when soil temperatures drop below 45 degrees Fahrenheit. Pansies can literally starve during the winter months even though the soil contains high amounts of ammoniacal nitrogen.
Generally, a thorough drenching of the soil at transplant with 150 parts per million of a soluble greenhouse fertilizer, such as 15-2-20, will get the plants off to a good start. Avoid high rates of nitrogen during September and later in April and May because the plants grow quickly and can stretch in warm weather under high nutrition.
Pansy plants are usually planted at spacings of 6 to 10 inches between plants. Although a 6-inch spacing makes the bed appear fuller, plants may become crowded and more susceptible to spider mites and diseases. A wider spacing allows better air circulation between plants and helps avoid these problems.
When the air temperature drops below 25 degrees Fahrenheit, pansy foliage will wilt and turn a gray-green color. This is a normal defense response to cold weather. Soil temperature gradients, especially in raised beds, can vary greatly due to micro-climate differences. For example, soil temperature on the south-facing slope of a pansy bed can reach approximately 45 degrees Fahrenheit F on a cold winter day, while 10 feet away, soil on the northern side of the same bed can be frozen solid to the depth of the root ball. The roots cannot absorb water from the frozen soil, and the plants on the north side of the bed could dehydrate and die. Frozen soils combined with drying winds can spell disaster for a pansy bed.
Pine straw, applied 2-4 inches thick over the top of the entire bed (plants and all) during extreme cold is one of the best ways to save a pansy planting from freeze injury. Pine straw helps trap heat in the soil, prevents it from freezing and greatly reduces exposure to cold, desiccating wind. Carefully rake the pine straw off the bed when the cold weather passes. Special frost protection fabrics have also been used successfully. These special freeze protection measures are generally taken only when the air temperature is expected to drop below 20 degrees Fahrenheit for several hours, when dehydrating winds accompany the cold, and when the soil is in jeopardy of freezing. Healthy plants can generally survive short periods of temperatures down to the single digits without protection.
When the weather cools and soil temperatures drop below 60 degrees Fahrenheit, begin a liquid feed program using a fertilizer containing at least 50 percent of its nitrogen in nitrate form. A standard 15-2-20, high-nitrate pansy formula fertilizer applied at 14-day intervals through March 15 provides excellent results. Formulations with nitrogen derived from potassium nitrate (KNO3), calcium nitrate (Ca(NO3)2) or magnesium nitrate [Mg(NO3)2] are recommended. These formulations also have little effect on soil pH, so nutrient deficiencies are less likely to occur.
Fertilization frequency depends on the vigor and performance of the planting. Consult the label for recommended application rates. If a period of warm weather occurs, cut back on the liquid feed to avoid foliar stretching during the midwinter. When foliar feeding is done, apply enough liquid not only to wet the foliage but also to saturate the root zone to a 4 to 6-inch depth.
Soil temperatures usually are on the rise by March 15, so fertilizers containing ammoniacal nitrogen can be used at that time. The standard fertility program used on summer annuals – 200 ppm 20-20-20 or a slow release/granular fertilizer – should work well for pansies during the remainder of the growing season.
Removing frost-damaged flowers and old, faded flowers should be a top priority with pansies. This not only improves the appearance of the color display but also prevents the onset of seed pods that consume the plants energy. It also reduces the changes of fungal blight diseases that feed on old blossoms. Trim lanky branches periodically to encourage branching, compact growth and improved flowering.
Get the soil tested again during the growing season. Soil pH should be between 5.4 and 5.8 for best growth. A soil pH above 5.8 can result in boron and iron deficiency; and high pH may lead to an increased incidence of black root rot, Thielaviopsis basicola (Jones, 1993).
If the soil pH rises above 5.8, drench at 10-day intervals with either iron sulfate or aluminum sulfate (1 to 3 pounds per 100 gallons) to lower the pH into the desired range. Lightly rinse pansies after application to prevent foliage injury from the drenches. Continue these corrective treatments until the soil pH drops and stays in the 5.4 to 5.8 range.
Excess soil moisture decreases both the oxygen content of the soil and root growth. Carefully monitor irrigation and try to keep pansies slightly on the dry side to “harden” growth prior to cold weather. If beds are continuously wet, even in periods of normal rainfall, consider making drainage adjustments.
Heat may also be a problem, causing pansy stems to stretch and become leggy. This is a particular problem when pansies are planted too early in the season. The F1 hybrids, such as the “Majestic Giants” series, “Regal” series, “Imperial” series and “Crown” series, are known to have superior heat tolerance.
Pansies are generally not affected by diseases or insects. However, where slugs are common, they will not bypass a bed of pansies. Either set out slug traps or sprinkle a bit of diatomaceous earth around the plants. If signs of mildew or any fungi are observed, take a sample leaf to a garden center for correct identification and plant treatment.