New perennials can be a challenge to grow

As the perennial market continues to expand, breeders are increasingly focusing their efforts on developing new varieties. Many new perennials were developed with growers’ needs in mind. They may be easier to flower or require fewer plant growth regulators. Some new varieties have distinctly different production requirements than older ones.

But a variety new to the market is not necessarily an improvement or worthy of addition to a grower’s perennial program. Unfortunately, with increasing pressure for new varieties to generate profits as quickly as possible, perennials may reach the market without having been thoroughly trialed in a range of production environments and outdoor climates. (Remember Coreopsis ‘Limerock Ruby’?) Growers should evaluate which new perennials they produce carefully, ideally after on-site trialing to verify that they will add value to their perennial programs.

Understanding introductions

It is challenging to keep up with all the new perennials coming to market, which suppliers offer them, and whether they are exclusive to specific marketing programs or open for general sales. Often, finding complete information about new varieties can be challenging. Far too often, breeder Web sites and marketing materials don’t include key information a grower needs for a variety -- including basics such as flower color, plant height and hardiness, let alone production requirements such as photoperiod or vernalization requirements.

New perennials

Here is information about producing some of the newer perennials on the market.

‘Snowfix’ is the first Arabis caucasica to flower without vernalization, ‘Snowfix’ should be grown cool (45°-55@ F) for best quality and flowering uniformity. Vernalization is not recommended. ‘Snowfix’ is ideal to produce in minimally heated greenhouses for early sales. Plants flower seven to eight weeks after transplant, regardless of photoperiod.

Final height: 5 inches.

Hardiness: 3-7.

Aquilegia x hybrida Double Winky series has three colors: White & White, Dark Blue & White and Red & White. They have attractive, upright-facing flowers with a double central ruffle. Plants need vernalization to flower and have a relatively long juvenility period before responding to cold. Growers can establish plants in their final container in late summer or early fall for overwintering or purchase vernalized liners. Plants flower six to seven weeks after transplant or warming overwintered containers, regardless of photoperiod.

Final height: 20 inches.

Hardiness: 2-9.

The Astilbe x arendsii Astary dwarf series is excellent and from seed. Colors are White, Pink and Rose Shades. ‘Astary’ should not be vernalized and must be grown under long days (natural or artificial) for good growth and uniform flowering. It is best grown warm (70°-75°), and flowers 10-12 weeks after transplant. If not using artificial lighting, do not transplant this series until days are at least 13-14 hours long, or plant quality and flowering percentage will be poor.

Final height: 10 inches.

Hardiness: 3-9.

Coreopsis grandiflora ‘Heliot,’ ‘Rising Sun’ and ‘Sunfire’ are first-year-flowerers that flower nine to 10 weeks after transplant (one to two weeks faster than ‘Early Sunrise’), when grown under long days (14-plus hours). ‘Heliot’ and ‘Sunfire’ have golden-yellow flowers with red centers. ‘Rising Sun’ has semi-double, yellow flowers with reddish centers.

Final height: ‘Heliot,’ 16-24 inches. ‘Rising Sun,’ 20-36 inches. ‘Sunfire,’ 20-24 inches. Hardiness: 4-9.

Delphinium grandiflorum Delfix (spurless flowers) and Summer  (spurred flowers) series are more compact than the older varieties. They generally do not require plant growth regulators in container production. They also have stronger stems, leading to fewer problems with stem breakage.

Best grown cool (55°-65@ F), they flower seven to nine weeks after transplant, regardless of photoperiod. New for 2008 is ‘Summer Morning,’ which has light-pink flowers.

Final height: Delfix series, 12-15 inches. Summer series, 10-14 inches.

Hardiness: 2-7.

Echinacea purpurea ‘Prairie Splendor’ is a true improvement in both habit and time to flower. It’s two weeks earlier to flower and significantly shorter than other purple-flowered seed echinaceas. Plants flower in 12-14 weeks from transplant of standard plugs, or nine to 11 weeks after transplant of vernalized liners, when grown under long days.

Final height: 18-24 inches.

Hardiness: 3-8.

Supply remains limited on the Echinacea Big Sky series, which are excellent, interspecific hybrids. Availability has been slowly getting better, but expect them to continue to be in somewhat limited supply as tissue-culture production methods continue to improve. All colors in the series flower without cooling in eight to 10 weeks after transplanting when grown under long days (14-plus hours). Harvest Moon has golden-yellow flowers with orange cones. It reaches 24-36 inches tall. Twilight has watermelon-red flowers and reaches 24-36 inches tall. It’s the most well-branched with fragrant flowers. Sundown has red-orange flowers. It reaches 32-36 inches tall and has slightly smaller flowers. It is somewhat taller than other series members. Sunrise has light-yellow flowers with green cones. It reaches 24-36 inches tall and is quite vigorous.

Hardiness: 4-9.

Gaillardia x grandiflora ‘ Arizona Sun’ and ‘ Granada ’ are significant improvements over ‘Goblin.’ They are more uniform in habit and flowering, and don’t require vernalization to flower. Even when vernalized, they flower much more uniformly than ‘Goblin.’ Plants flower six to eight weeks after transplant of vernalized liners, or 12 weeks after transplant of standard plugs, when grown under long days.

Final height: 12 inches.

Hardiness: 2-9.

Gaillardia ‘Oranges & Lemons’ is a newer vegetative selection. This interspecific hybrid is only hardy to USDA Hardiness Zone 6, but even in cold climates it is floriferous and long-flowering enough to be used as an annual. It flowers four to six weeks after transplant of liners when grown under long days, but may need pinching to fill containers 1 gallon and larger. Pinched plants rebloom in two to four weeks.

Final height: 18-24 inches.

Hardiness: 6-9.

Heuchera x hybrida ‘Melting Fire’ is a seed form with ruffled, purple foliage. It’s more economical than vegetative selections. It can be sold without flowers and generally fills containers six to eight weeks after transplant, regardless of photoperiod. Flowers are creamy-white. Seed supply is limited.

Final height: 15-18 inches

Hardiness: 4-9.

It is challenging to produce high-quality flowering Iberis sempervirens. Plants tend to be poorly branched and drop lower leaves by the time they bloom. ‘Tahoe’ is an excellent, dwarf, very well-branched cultivar that is a significant improvement over both seed and vegetative alternatives. It requires vernalization and flowers six to seven weeks after transplant of vernalized liners, regardless of photoperiod.

Final height: 8-10 inches tall.

Hardiness: 3-9.

Unrooted cutting suppliers have been successful in virus indexing and cleaning up many of the established Phlox paniculata varieties. Notable varieties include ‘Blue Boy’ (near true-blue flowers), ‘Orange Perfection’ (salmon-orange flowers), ‘Starfire’ (cherry-red flowers) and ‘Laura’ (purple with white eye).

Growers interested in a dwarf P. paniculata should consider the ‘Flame’ series (12-18 inches tall). Pinching may be helpful for plants grown in gallon or larger containers, and adds three to four weeks to the production schedule.

P. paniculata varieties generally flower without vernalization 10-12 weeks after transplant, when grown under long days (14-plus hours). Flowering is slightly faster (nine to 10 weeks after transplant) when vernalized liners are used.

Hardiness: 3-8.

Pink-flowered vegetative Salvia x sylvestris cultivars have finally found their way to market. ‘Pink Friesland ’ has dark-pink flowers and reaches 16-20 inches tall. ‘Sensation Rose’ is 12-14 inches tall and has light-pink flowers. Both cultivars flower six to seven weeks after transplant when grown under long days, or five to six weeks after transplant of vernalized liners.

Hardiness: 4-9.

2 trends emerge for perennials

Trend: Eliminating viruses

In addition to truly new genetics, another trend is expanding growers’ options with perennials. Many cutting suppliers are focusing on cleaning up proven, older varieties that have often become infected with viruses over decades (or longer) of vegetative propagation.

Through innovative tissue culture propagation, these older varieties can be refreshed and reinvigorated, often leading to a virus-indexed variety performing significantly better than plant material that has not been cleaned up.

Clean varieties are often well worth a price premium, based on reduced shrink in production and overall performance improvement.

Species that most noticeably benefit from this cleanup process include Salvia, Phlox paniculata, Phlox subulata and Lavandula.

Trend: Patents, royalties

Another trend is the increasing number of patented varieties that require royalty payments. Breeders use patents to protect their varieties from unlicensed propagation and to generate revenue from their introductions.

Many breeders are allowing their patented varieties to be propagated and not requiring that growers pay a licensing fee beyond the royalty to expand their presence in the market.

Perennial royalties can range from $0.04-$0.25 or higher, per plant. Because a royalty can more than double the cost of a cutting or rooted liner, growers should carefully evaluate the cost of patented varieties against the value they bring to a perennial program.

A unique patented variety that can stimulate purchases may be more than worth the extra cost. A patented variety that doesn’t add much value may not be worth it.

- Allen R. Pyle

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Allen R. Pyle is the perennial guru and a marketing specialist for C. Raker & Sons Inc., (517) 542-4524; www.raker.com.