Zonal differences

Editor’s note: This article is part two of an interview with plantsmen across North America. See the first part in the July 2016 issue: bit.ly/best-of-trials

One of the most noble characteristics of our industry is the seemingly incongruous fact tha t our competitors are also our colleagues, our customers, and oftentimes, our friends. In that spirit of sharing, top plantsmen from Manitoba to Georgia gave their insight into the top performing varieties in seven key genera that every perennial grower and retailer can offer with confidence.

Whether you’re just getting into the perennial production business, or have been struggling in a key area, solid recommendations for USDA Hardiness Zones 3-8 follow. Still have questions? Seek out these perennial gurus at the next trade show or give them a ring.

Top-performing Echinacea

ZONE 3A

Best in class:E. purpurea Prairie Splendor, E. ‘Cheyenne Spirit’

Key to success: Insulating snow cover is an absolute must for overwintering success.

Zone 4A

Best in class:E. purpurea, E. purpurea ‘Magnus,’ E. purpurea ‘White Swan,’ E. ‘Cheyenne Spirit;’ native prairie species

Key to success: Insulating snow cover and choosing the right varieties for this climate.

Zone 5B

Best in class:E. purpurea ‘Pica Bella’ and E. purpurea ‘Milkshake’ for stem strength and flowering performance; Sombrero Adobe Orange for vibrant orange flowers over a long period

Key to success: Well-drained soil in both summer and winter.

Zone 6A

Best in class:E. purpurea ‘PowWow Wild Berry’ for its superior habit, high bud count and garden performance; Sombrero Salsa Red for color, self-branching habit and ease of production

Key to success: Removing flowering stems tight to crown in the bulking stage until they reach desired size.

Zone 6B

Best in class: Seed-grown cultivars like ‘Cheyenne Spirit’ and the E. purpurea PowWow series for greater vigor and improved winter hardiness

Key to success: Well-drained soil and watching for aster yellows disease.

Zone 7A

Best in class:E. purpurea ‘White Swan,’ E. ‘Cheyenne Spirit,’ E. tennesseensis, E. tennesseensis ‘Rocky Top’ for a longer life span

Key to success: Adjusting expectations to know this is not a long-lived perennial; excellent drainage for E. tennesseensis types; cutting off the blooms the first year so plants put down stronger roots.

Zone 8A

Best in class:E. purpurea for survivability, Sombrero Flamenco Orange for flower power

Key to success: Understanding that echinacea will be short-lived in this zone due to lack of chilling over winter and summer heat stress, which leads to disease.

Top performing Monarda

Zone 3A

Best in class:M. didyma Grand Parade and Grand Mum for their attractive form, winter hardiness and good mildew resistance

Key to success: Snow cover is beneficial; easy to overwinter in this zone.

Zone 4A

Best in class:M. didyma Grand Marshall and Grand Parade

Zone 5B

Best in class: ‘Raspberry Wine,’ M. didyma ‘Peter’s Fancy Fuchsia’

Key to success: Well-drained soil in summer and winter.

Zone 6A

Best in class: Sugar Buzz ‘Rockin Raspberry’ for its vigor in production, great mildew resistance, mid-sized stature, colorful spring foliage, and eye-catching flower color

Key to success: Plant plugs in late summer for sales the following spring. Early planting results in premium finished product that can be forced easily for spring sales.

Zone 6B

Best in class: Native M. bradburiana for mildew resistance, though it can spread rapidly if left unchecked

Key to success: Choosing the right varieties for this climate; monarda can be tough to grow here due to hot, humid summers with warm nights.

Zone 7A

Key to success: Choose cultivars that have proven resistance to powdery mildew; plants can spread very rapidly and need to be kept in check.

Zone 8A

Best in class:M. bradburiana hybrids Leading Lady series for their compact habit, very good mildew resistance and incredible flower power early in the season

Key to success: Choosing the right varieties for this climate; modern hybrids seem to have better garden performance.

Top performing Phlox

Zone 3A

Best in class:P. paniculata Flame series for its attractive form and earlier bloom time in this zone where the growing season is short

Key to success: Overwinters easily in well-drained soil and full sun.

Zone 4A

Best in class:P. paniculata ‘David’ and ‘David’s Lavender’ for their mildew resistance; P. caroliniana ‘Lingard’ which blooms early and is mildew resistant

Key to success: Keeping plants healthy (free of spider mites and powdery mildew) going into winter.

Zone 5B

Best in class:P. paniculata ‘Shortwood’ for best mildew resistance ever in phlox trials; P. paniculata ‘Coral Crème Drop’ for excellent floral display on strong, healthy plants; P. maculata ‘Flower Power’ for no disease issues and exceptional floral display

Key to success: Well-drained soil and good air flow between plants.

Zone 6A

Best in class:P. paniculata ‘Glamour Girl’ for its excellent vigor and crop uniformity, strong resistance to powdery mildew and other foliar diseases, and hot coral pink flowers on strong stems

Key to success: Start phlox from bare root in spring to yield a full container with many stems in a short 6- to 8-week crop time.

Zone 6B

Best in class:P. paniculata ‘Jeana’ and Flame series for their resistance to powdery mildew

Key to success: Keeping plants healthy going into winter; snow cover is not essential.

Zone 7A

Best in class: Hybrid phlox ‘Minnie Pearl’ and ‘Wanda,’ P. paniculata ‘Peacock White,’ ‘Jeana’ and ‘Robert Poore’

Key to success: Choosing disease resistant varieties, deadheading to promote several rounds of rebloom, some afternoon shade.

Zone 8A

Best in class:P. paniculata ‘Peacock White’ for its mildew resistance, clear white flowers and sturdy upright habit

Key to success: Keeping plants consistently moist in summer and providing some afternoon shade.

Top performing Sedum

Zone 3A

Best in class: ‘Elsie’s Gold,’ ‘Autumn Joy,’ ‘Autumn Fire,’ ‘T-Rex’ for their ease in production and excellent landscape performance

Key to success: Well-drained soil and full sun.

Zone 4A

Best in class: ‘Autumn Joy,’ ‘Abbeydore,’ S. spectabile ‘Neon,’ S. kamtschaticum and S. kamtschaticum ‘Variegatum’

Key to success: Planting high in heavy clay soil, providing good soil and surface drainage.

Zone 5B

Best in class:S. tatarnowii hybrid ‘Thundercloud’ for its tightly mounded habit; ‘Soft Cloud’ for its plentiful, light pink flowers; ‘Firecracker’ for its tight habit and glowing red leaf color

Key to success: Well-drained soil in both winter and summer, lower soil fertility.

Zone 6A

Best in class: ‘Pure Joy’ for its incredible flower power, compact habit, premium appearance in containers for retail sales, and excellent landscape performance

Key to success: Full sun and slightly drier conditions.

Zone 6B

Best in class:S. tatarnowii hybrid ‘Thundercloud’ for its very compact habit and excellent flower coverage

Key to success: Well-drained soil, especially in winter.

Zone 7A

Best in class:S. repestre ‘Angelina’, S. tetractinum, and Phedimus takesimensis (syn. S. takesimense)

Key to success: Well-drained soil and full sun.

Zone 8A

Best in class:S. mexicanum ‘Lemon Ball’ for landscapes and containers, a stronger grower than S. repestre ‘Angelina’ in this climate

Key to success: Well-drained soil, consistent moisture during the hottest summer months, dislikes competition,

Top performing Leucanthemum

Zone 3A

Best in class:L. superbum ‘Snowcap’ for its excellent form and winter hardiness; L. superbum ‘Starburst’ for its flower power

Key to success: Plenty of snow cover, choosing the best varieties for this climate.

Zone 4A

Best in class:L. superbum ‘Alaska’ for winter hardiness

Key to success: Plants tend to rot in spring if they remain wet for extended periods; amend soil for improved drainage.

Zone 5B

Best in class:L. superbum Daisy May for its incredible flower power and shorter height; L. superbum ‘Amelia’ from seed

Key to success: Well-drained soil.

Zone 6A

Best in class:L. superbum Daisy May is the best reblooming variety with amazing flower power, strong stems that do not flop, and no need for PGRs in production

Key to success: This variety wants to flower too quickly in production, so it is best to remove all flower buds until plants reach their desired size.

Zone 6B

Best in class:L. superbum ‘Whoops-a-Daisy’ for its short stature and increased tolerance of less-than-perfect soil drainage

Key to success: Plants tend to rot if the soil is not well-drained, especially in winter.

Zone 7A

Best in class:L. superbum ‘Becky’

Key to success: An older variety, but the only one that has proven to be tough-as-nails and long-lived, easily handling the freeze/thaw cycles that are common in this climate.

Zone 8A

Best in class:L. superbum ‘Lucille White’ for its shorter habit

Key to success: Leucanthemum is tough in this climate due to lack of winter chilling and warm summer nights, which encourage disease.

Top performing heuchera

Zone 3A

Best in class: Arctic Mist’ for its superior winter hardiness and compact habit

Key to success: Reliable snow cover is essential.

Zone 4A

Best in class: ‘Brandon Pink’ for its extreme winter hardiness, ‘Snow Angel’ and native species

Key to success: Reliable snow cover to reduce heaving.

Zone 5B

Best in class: ‘Cherry Cola’ for its sun tolerance, vibrant red-brown foliage and strong flowering performance; H. villosa hybrid ‘Color Dream’ for its outstanding garden performance and tendency to be long-lived

Key to success: Well-drained soil and reliable snow cover to reduce heaving.

Zone 6A

Best in class:H. villosa hybrid ‘Berry Timeless’ for its everblooming flowers on proportional stems, attractive mint green foliage and excellent sun tolerance

Key to success: Well-drained soil; avoid deep shade as this reduces flowering.

Zone 6B

Best in class: Missouri native H. richardsonii; any heuchera with villosa parentage

Key to success: Choosing the best varieties for this climate.

Zone 7A

Best in class: Must be a H. villosa type to withstand the summer heat; best varieties include ‘Caramel’, ‘Citronelle’, ‘Delta Dawn’ and ‘Autumn Bride’

Key to success: Protection from hot afternoon sun, well-drained soil. Most varieties grow best in containers though ‘Autumn Bride’ and ‘Delta Dawn’ have performed well in-ground for several years.

Zone 8A

Best in class:H. villosa hybrid ‘Georgia Peach’ and any heuchera with villosa parentage; ‘Rave On’ for excellent flowering performance

Key to success: Growing in shade and providing consistent moisture.

Top performing Lavandula

Zone 3A

Best in class: All lavenders are a bit tender; decent success with L. angustifolia ‘Hidcote Blue’ and L. x intermedia Phenomenal

Key to success: Lots of snow cover and a very mild winter will aide in overwintering success, otherwise grown as annuals.

Zone 4A

Best in class: All varieties grown strictly as annuals, none notable

Key to success: Adjusting expectations--don’t expect lavender to overwinter in this climate.

Zone 5B

Best in class:L. x intermedia Phenomenal, L. angustifolia ‘Imperial Gem,’ L. angustifolia ‘Royal Velvet’

Key to success: Well-drained soil in both winter and summer.

Zone 6A

Best in class:L. angustifolia ‘Essence Purple’ for its consistent shape that holds all season and earlier bloom time; L. x intermedia Phenomenal for disease resistance and ability to handle extreme temperature swings

Key to success: Well-drained soil and full sun; protect the evergreen foliage from drying out in winter winds.

Zone 6B

Key to success: Well-drained soil is essential for surviving the wet, cold winter.

Zone 7A

Best in class:L. x intermedia Phenomenal for its reliability, L. x intermedia ‘Grosso’

Key to success: Well-drained soil, especially in winter and full sun; prune back by no more than 1/3 immediately after flowering; replace plants every 5-6 years.

Zone 8A

Best in class:L. stoechas varieties such as ‘Blue Star,’ L. x intermedia ‘Dutch’ for its fantastic silver foliage and tendency to be longer lived

Key to success: No wet feet, especially in winter.

Susan Martin specializes in horticultural marketing, content generation and management, working with green industry clients in trade and consumer sectors. She can be reached at gardenersuesnews@gmail.com.