Pennisetum orientale ‘Tall Tails’

May 12, 2004 - 07:31

There is a place in nearly every landscape design for ornamental grasses. Perhaps the most suitable and versatile ornamental grasses are the pennisetum cultivars. Pennisetum varieties range in size from 6 inches to 8 feet high. They are easy to grow and work well in mass plantings, used alone or as small groupings in perennial borders. Pennisetum orientale ‘Tall Tails’ will form large clumps reaching 8 feet high by 5 feet wide when they reach full size. The violet-pink foxtail plumes arch above and away from the blue-green foliage by more than 12 inches. Tall Tails always provides a stunning display both during the growing season and during the winter months.

Pennisetum orientale, which originated in Pakistan, is hardy in USDA Zones 5-11. Tall Tails is a vigorous, heat-loving cultivar that performs best under full sun but will also grow well with some partial shade. Interestingly, Tall Tails originated as a USDA forage crop variety and has transformed into one of the most exciting ornamental grass introductions in recent years. It performs well in areas with well-drained soils and needs to be irrigated during dry periods.

Propagation

Tall Tails, like most cultivars of pennisetum, is propagated by division. Commercially, divisions are most commonly done in early spring, but pennisetum can successfully be divided throughout the year. When planting, pay particular attention to ensure the potting substrate comes into good contact with the propagule, and do not let the medium dry out until the division is well rooted. The biggest mistake growers make when planting ornamental grasses by division is that they don’t water them properly after transplanting, allowing them to dry out, which reduces plant vigor and possibly even leads to plant death. If the proper conditions exist, Tall Tails will root easily after division.

Production

When planting divisions or rooted plug liners of Tall Tails, it is important for the root ball to be in good contact with the potting medium and to properly manage the initial moisture levels for the first couple of weeks. Try to avoid air pockets between the division and the medium, and do not provide conditions that will lead to water stress. Divisions are most commonly used during early spring, while plugs are transplanted throughout the production season. When transplanting plugs, try to avoid planting them too high or too low; always plant to match the original soil line of the plant. If the crown of Tall Tails is planted below the soil surface a crown rot is likely to occur. It is important to keep the root zone of newly potted grasses moist but not wet until they become established. Once they are fully rooted, pennisetum can be allowed to dry out more fully between waterings.

When transplanting Tall Tails, I recommend using a growing medium with adequate drainage and water-holding capacity. Oriental fountain grasses are moderate feeders and perform best when a constant liquid fertilization program is used, feeding at rates of 100-150 ppm nitrate. For growers using controlled-release fertilizers, I would suggest incorporating it at a rate equivalent of 1.25-1.5 lbs. of nitrogen per yard of growing medium. The pH of the growing medium should be maintained within the range of 6.0-6.5.

Pennisetum orientale is a heat-loving ornamental grass. For plant establishment, it is recommended to maintain average temperatures of 65-75º F. At these temperatures a 1-gal. container can reach finished size from divisions or 21-cell plugs in 7-9 weeks. Tall Tails should be produced under high light levels with a minimum of 5,000 foot-candles. Lower light levels or areas of partial shade are still adequate for plant growth and development but will cause the foliage to take on a lighter green coloration. Plants grown under shade with consistently low light levels tend to become floppy and have lower quality characteristics.

pests & diseases

Insect problems are generally a rare occurrence with commercial pennisetum production. Japanese beetles, spider mites, spittlebugs and whiteflies may occasionally be observed feeding on pennisetum. They seldom cause significant plant damage and can be controlled relatively easily using the appropriate contact insecticides, if routine scouting has determined control measures should be implemented.

Plant pathogens are also not very common with this variety of pennisetum. The most common disease — crown rot — occurs within a couple of weeks of transplanting. Improper planting practices and/or poor irrigation management are often responsible for many of the root or crown rot problems that growers experience. Other potential causes of root rots of pennisetum include high salt levels in the media, poor physical properties of the media or being grown in the same pot/medium for too long. Any of these conditions could lead to plant stress and the onset of root rot pathogens. Try to pick a medium that has good water-holding and drainage characteristics and will not deteriorate or settle over time.

Monitor the irrigation practices and fertility levels on a regular basis, making adjustments accordingly. When possible, do not hold pennisetum in a pot for an extended period of time (12 months or more). When these measures are taken, most crown and root rots can be prevented.

Controlling Plant Height

As Tall Tails is a tall and vigorous variety, it may be necessary to take steps to reduce the overall plant height while it is being produced in a container. The first strategy would be to implement a trimming program. Plants can be regularly trimmed back to control the height of the plant as well as to encourage lateral branching, providing a fuller high-quality product. The general rule of thumb is to only cut or remove one-third of the plant growth at a time. Cutting back more than one-third the growth at any given time will not only slow crop development but will also have a negative impact on plant quality.

The second strategy to control plant height would be to apply PGRs to the crop. Unfortunately, I am not aware of any specific research that has been conducted on this variety and therefore, cannot make any solid recommendations at this time. From my experience with other cultivars of pennisetum and ornamental grasses, I can say that the best results have come from drench applications, while spray applications have been rather ineffective. Until the proper research has been conducted, experiment with different applications. The work I have conducted suggests growers should begin their testing of growth regulator drenches using A-Rest at 5 ppm, Bonzi at 6 ppm, or Sumagic at 1 ppm. Always conduct trials on a small scale before implementing PGR applications over the entire crop.

Availability

Tall Tails is available as a plug or finished container from many reputable companies across the country. Tall Tails is being marketed as part of the John Greenlee Collection through EuroAmerican Propagators.

About The Author

Paul Pilon is head grower at Sawyer Nursery, Hudsonville, Mich. He can be reached by E-mail at paul@perennialsolutions.com.

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