CULTURE NOTES
4/28/2017

Royal Collection Pennisetums

Josiah Raymer
Love dark, dramatic foliage, but worried about fading? Royal Collection Pennisetum varieties have purple-black foliage that actually deepens in bright light and high heat. This collection gives you the best of both worlds—the look of phormium along with the vigor and other characteristics of pennisetum. Selections include Prince, Princess, Princess Caroline, Princess Molly, First Knight, Majestic, Regal Princess, Royal Lady and most recently, Noble (pictured).

  • Prince reaches 5- to 6-ft. tall with broad, royal purple dappled blades.
  • Princess has a similar habit and tone to Prince, but reaches only 3 to 4 ft.
  • For smaller spaces, choose Princess Caroline or Princess Molly. Princess Caroline’s brilliant purple leaves are longer and more arched than Princess’ blades. The smallest, Princess Molly, reaches just under 2 ft. with deep burgundy foliage.
  • First Knight has center leaves that are very upright, surrounded by arching outer leaves. It has the family’s deepest, darkest, blackest purple foliage, plus a dark red midrib, and reaches 48- to 54-in. tall.
  • Majestic bears long, broad, rich purple-red leaves and tops out at 6 ft.
  • Regal Princess has features similar to Princess, with improved purple color and enhanced disease resistance, and reaches 3- to 4-ft. high.
  • Royal Lady has upright blades that emerge green, then darken with heat and sun to maroon, and finally, royal purple with a red midrib. It reaches a height of 4 to 5 ft.
  • Noble bears dark, upright blades that are such deep purple that they look black. They’re also thinner and darker than much of the collection, and Noble reaches over 6 ft. in a rounded clumping habit—the largest selection in the collection.
Garden- or container-friendly, the Royal Collection works well in combinations with both annuals and perennials. Each of these ornamental Napier grasses serves well as a specimen or in mass plantings. They’re low-maintenance, with increasing disease resistance as the collection goes on.

Appropriate pot sizes
Producing these pennisetums requires surprisingly little adjustment on the grower’s part. Perhaps most important: Be aware of mature height when potting up your liners. The appropriate pot size for the smallest, Princess Molly, won’t be the same as the largest, Noble.
  • Plant one plant per one trade gallon pot for Princess, Princess Caroline, Princess Molly, First Knight, Regal Princess and Royal Lady.
  • Plant one plant per 1- or 2-gal. pot for the largest of the series, including Noble, Prince and Majestic. Avoid putting Princess Molly in a 3-gal.; its petite size just isn’t a good fit for these oversized finished pots.
  • Plants will be finished for spring sale in approximately eight to 10 weeks.
Cultural considerations
  • Growing media: Choose a well-draining commercial media.
  • Growing temperature: Maintain at 70 to 80F (21 to 26C) days and 55 to 65F (12 to 18C) during nighttime.
  • Soil pH: Aim for a pH of 5.8 to 6.2.
  • Soil EC: Keep electrical conductivity at 1 to 1.5 mS/cm using the 2:1 extraction method.
  • Fertilizing: Provide a constant liquid feed at low levels of 100 to 150 ppm nitrogen.
  • Moisture level: Allow plants to dry between ample waterings.
  • Daylength: These pennisetums prefer long days and supplemental lighting of 12+ hours photoperiod.
  • Vernalization requirements: Vernalization isn’t required for the Royal Collection.
  • PGRs/pinching: Generally, the Royal Collection doesn’t need either.
Pests and diseases
Generally, pests and diseases aren’t a problem with proper protocols in place. This should include maintaining good air circulation and managing humidity levels. Monitor for aphids, mealybugs, spider mites, root rot and crown rot.

Follow a monthly broad spectrum fungicide control program, though breeding for better disease resistance has greatly reduced the need for the rotation. Apply a preventive fungicide drench at liner planting/transplant. GT


Josiah Raymer is head grower and general manager for Emerald Coast Growers, one of the country’s largest ornamental grass producers.