This has been a horrendous September where I live in Oregon’s beautiful Willamette Valley. Our lush valley has been inundated with smoke from nearby fires in the Cascade Range. Over 1 million acres are ablaze right now as I write this article. The American West is facing an ecological catastrophe fueled by climate change. We have a very long and challenging road ahead of us, and we must find the collective will to actually deal with this problem. These Green Guides that I’ve written for the past three years have been all about recommending plants for our industry that I feel have particular merit and should be grown more widely. This month, I’ve chosen to write about the genus Arctostaphylos, the manzanitas. Many species are both beautiful in the landscape and are adapted to survive fire.

I don’t really know any plants that just won’t burn, though manzanitas are somewhat fire resistant. They don’t burn easily, but their greatest evolutionary advantage lies in the fact they are fire “adapted.” Many species of Arctostaphylos native to the Western United States need fire for their seeds to germinate. About two-thirds of all manzanita species reproduce though obligate seeding, whereby plants do not resprout after a fire and rely only on seeding to regenerate their population. Imagine every adult in a species being wiped out in a catastrophic fire. The species would become extinct if not for the fact that its seeds were left behind by the fire. In fact, the intense heat of the fire cracked open the seed and allowed germination, and thus survival of the species. Obligate seeding allows for a genetically diverse population that is able to adapt and evolve much faster than species that reproduce by resprouting.

The biggest reason we should be growing more manzanitas is that they are beautiful landscape plants. The genus contains groundcover plants, as in the species uva-ursi and its cultivars. It also contains a plethora of beautiful shrub and small tree species. Arctostaphylos species are covered with bell-shaped flowers arranged in clusters in late winter and early spring and provide a good nectar source for early hummingbirds and bees. Many species have attractive reddish bark, adding to their alure as a landscape plant. Among my favorite cultivars is ‘Greensphere’, which has somewhat dense spherical shape and stays under 3 feet tall. I also love the pale, almost white foliage and pink stems of A. silvicola ‘Ghostly’, which grows into a small tree, reaching 8 feet in just five years. There are many other beautiful and garden-worthy varieties to consider. Most West Coast natives are hardy to USDA Zone 7, with a couple even to Zone 6. Colorado natives are Hardy to USDA Zone 4, as in Arctostaphylos x coloradoensis ‘Panchito’.

In January 2020, President Trump announced the United States would join World Economic Forum's One Trillion Trees Initiative, an ambitious global effort to grow and conserve one trillion trees worldwide by 2030. He made good on that announcement in October and established the One Trillion Trees Interagency Council, which will be responsible for coordinating the federal government’s support of the global One Trillion Trees Initiative. You can read the Executive Order (EO) here: http://bit.ly/executive-order-trees.

In it, Trump named the U.S. Secretary of the Interior David L. Bernhardt as co-chair of the council, along with U.S. Secretary of Agriculture Sonny Perdue.

The EO directs the Council to develop, coordinate and promote the Federal government’s interactions with the One Trillion Trees Initiative to promote tree growing, conservation, restoration and coordination with key stakeholders. In addition to the two co-chairs, the EO designates 21 other members of the Council to develop and implement a strategy to facilitate growth, restoration and conservation of trees.

“When I was growing up on my family farm, my father always taught me to appreciate that ‘when it comes to the land, we want to leave it better than we found it.’ The President’s Executive Order will do just that — leave it better than we found it and help bolster the 193 million acres of National Forest System lands to promote recreation, enjoyment, and sustainable economic prosperity across broad sectors of the rural economy,” Perdue said in a statement released by the U.S. Department of the Interior.

The council is independent of the broader One Trillion Trees Initiative, according to Craig Regelbrugge, senior VP of public policy and government relations at AmericanHort.

The global initiative (www.1t.org) and the U.S. chapter (us.1t.org) has the same goal: to promote a nature-based solution to climate change and “to connect, empower and mobilize a global reforestation community to conserve, restore and grow one trillion trees globally by 2030.”

There are 19 governmental agencies named in the EO that will be part of the council, so my hope is that this initiative doesn’t get bogged down in red tape or swept aside by partisan politics. But this statement helps ease my skepticism:

“Colleagues from both sides of the aisle are lending their support to the Trillion Trees Act, demonstrating its tremendous potential to combat our changing climate, conserve our natural resources, and facilitate growth in environments nationwide,” says U.S. Rep. Steve Stivers (R-Ohio). “In Ohio’s 15th District alone, the President’s executive order will make a difference for the Wayne National Forest, and a number of state parks including the Lake Alma State Park, Hocking Hills and Old Man’s Cave. These forests and woodlands produce recreational opportunities for every family and putting these resources to work in the effort to remove carbon from our atmosphere will deliver positive economic and social benefits for generations to come.”

This initiative already has some nursery industry support, and I’ll bring you those details in an upcoming issue.

What do you think about this EO? How would you like to get involved? I’d love to hear from you.

Ironweeds inhabit a broad swath of the United States, from the Mid-Atlantic to the Midwest and from Minnesota south to Texas. While many are tall, even towering in height, all ironweeds offer an abundance of purple-hued flowers in late summer and early fall. Their value as a food source for pollinators is irrefutable — scores of bees, butterflies and numerous other insects feverishly work the flowers throughout the late bloom season. Ironweeds are extraordinary ecological plants, due to their indigenousness and importance as powerhouse pollinator plants, but they are great garden plants, too. At a glance, some ironweeds may seem too tall for many gardens, but recent breeding has resulted in a number of compact hybrid selections. The shorter ironweeds may have given up some size but have lost none of their ornamental appeal or draw for pollinators. Vernonia spp. are in the aster or daisy family (Asteraceae), but lack the showier petal-like ray florets common to the composite inflorescences of coneflowers (Echinacea spp.), asters (Symphyotrichum spp.) and sunflowers (Helianthus spp.). For several weeks beginning in mid- to late summer, purple to magenta capitula bloom in many-flowered inflorescences measuring up to a foot or more across. Leaves are typically dark green and tend toward lance-shaped but can be willow-like to filiform. Conversely, silver ironweed sports bright silvery white linear leaves. Leaf size enhances the robustness of some ironweeds; for example, giant ironweed (V. gigantea) reaches 8 feet tall, but the 10-inch long leaves make it seem even larger. On the other hand, at 3 inches long and barely wider than a sliver, the linear leaves of narrowleaf ironweed (V. lettermannii) look more like Arkansas blue star (Amsonia hubrichtii) than any of its kin.

Most of the commonly cultivated species have woody, fibrous root crowns and stiff stems ranging from several feet to 10 or more feet in height. Ironweeds are generally easy to grow in full sun and moist, well-drained soils but are often adaptable to light shade and drier soils, and some species are drought-tolerant once established. Silver ironweed, for example, is best grown in lean, gravelly soil or decomposed granite, in full or half-day sun. Ironweeds tend to grow taller in moist conditions.

Many ironweeds are hardy to at least USDA Zone 5 or colder, while others are native to warmer places in the Southeast and westward to Texas. Ironweeds are typically long-lived, growing into large clumps over time, but rarely need division. Deadheading reduces unwanted seedlings, which can be prolifically produced, especially in moist areas; however, deadheading removes a food source for late-season songbirds. Powdery mildew and rust can infect foliage in late summer or fall — some species are more susceptible than others. Disease levels can be severe, thus deleteriously affecting plant health. The bitter-tasting leaves are usually not palatable to most grazing mammals including deer. Ironweeds are both a boon and a challenge to gardeners — their size can be daunting for average gardens, but their late-blooming purple flowers attract a host of pollinators. Ironweeds put on an impressive show in native and naturalistic landscapes, meadows and formal gardens.

In early summer, the dark green foliage provides a handsome backdrop for a variety of earlier -blooming perennials; whereas, late-season bloomers such as sunflowers (Helianthus spp.), goldenrods (Solidago spp.), and big bluestems (Andropogon gerardii cultivars) make stellar floral companions. A shorter stature and feathery foliage sets narrowleaf ironweed (V. lettermannii) apart from other species, and provides a pleasing textural contrast with bolder plants. Despite the large number of species — upward of 1,000 herbaceous and woody plants from the Americas, Asia, Africa, and Australia — ironweeds are not widely cultivated and still are uncommon in home gardens.

The evaluation study

The Chicago Botanic Garden (USDA Hardiness Zone 5b, AHS Plant Heat-Zone 5) undertook a comparative trial of Vernonia species and cultivars from 2012 through 2018. The goal of the trial was to determine the garden-worthiness of a variety of cold-hardy ironweeds. The trial group consisted of 17 taxa in all—representing ten species with eight associated subspecies, cultivars, or hybrid selections. Plants were acquired commercially or were grown from wild-collected seeds; seed-grown species exhibited variable traits within a taxon and included V. arkansana, V. baldwinii, V. fasciculata, V. gigantea, V. gigantea ssp. gigantea, V. glauca, V. missurica and V. noveboracensis. The ironweed trial was originally initiated in 2009 but was interrupted in 2010 by a renovation project in the evaluation garden. Due to significant changes in bed design, all plants were transplanted to pots and moved to the production nursery in June 2010. The original 11 taxa were replanted in the trial garden in September 2011; the official restart of the trial began with data collection the following spring. Several new taxa were added to the trial between 2012 and 2015 including V. angustifolia ‘Plum Peachy’, V. gigantea ssp. gigantea ‘Jonesboro Giant’, V. noveboracensis ‘White Lightning’, V. ‘Southern Cross’, V. ‘Summer’s Surrender’ and V. ‘Summer’s Swan Song’.

Five plants of each taxon were grown in side-by-side plots for easy comparison of ornamental traits and landscape performance. The evaluation garden was openly exposed to wind in all directions and potentially received up to 10 hours of full sun daily during the growing season, which averaged 175 days per year for the 2012-2018 trial period. The clay-loam soil had a pH of 7.4 during this period, and although typically well-drained, the site occasionally retained excess moisture for short periods in all seasons. Maintenance practices were kept to a minimum, thereby allowing the plants to thrive or fail under natural conditions. Trial beds were irrigated via overhead sprinklers as needed, mulched with composted leaves once each summer, and regularly weeded. Moreover, plants were not deadheaded, fertilized, winter mulched, or chemically treated for insects or diseases. Plants were cut back to near the base in late winter before new growth began.

In the trial, the ironweeds were regularly observed for their cultural adaptability to the soil and environmental conditions of the full sun evaluation garden; diseases and pests; winter hardiness and survivability; and ornamental qualities associated with foliage, floral display, and plant habits. All taxa were evaluated for a minimum of four years, except for ‘Plum Peachy’, which died during the second winter in two different trials, and ‘White Lightning’, which had been in the garden for only three years when the trial was terminated in autumn 2018.

Top-rated ironweeds

Four ironweeds received five-star excellent ratings, including V. gigantea ssp. gigantea ‘Jonesboro Giant’, V. lettermannii ‘Iron Butterfly’, V. ‘Summer’s Surrender’ and V. ‘Summer’s Swan Song’. These top-rated ironweeds featured superior ornamental traits such as strong vigorous habits, handsome foliage, heavy flower production, winter hardiness, and disease resistance.

‘Jonesboro Giant’ was the largest ironweed in the trial, reaching 144 inches tall and 60 inches wide. ‘Jonesboro Giant’ differed from the subspecies in being significantly taller and narrower in habit, and flowering seven to 10 days earlier. The rigid stems were upright at all times, although the plants relaxed a bit in October during peak bloom. The fine-textured inflorescences and upper stems were dark burgundy. Flower production was consistently heavy, with smallish, ¾-inch-wide purple flower heads; the inflorescences were commonly more than 12 inches wide. The large, dark green leaves were generally healthy, with only minor powdery mildew observed. The late bloom period of ‘Jonesboro Giant’ — late September to early November — was occasionally truncated by early frosts in October; the historical frost date at the Chicago Botanic Garden is October 15. In addition, the large leaves were sometimes tattered by strong winds, especially on the upper half of the stems.

The soft, needle-shaped leaves of ‘Iron Butterfly’ had a similar feathery appearance to another Arkansas native — spring-blooming blue star (Amsonia hubrichtii) — rather than to any of the other ironweeds. ‘Iron Butterfly’ originated in the University of Georgia’s trial garden, and was selected for its vigorous growth, compact habit, and floriferous nature. At 33 inches tall, ‘Iron Butterfly’ was 10 inches shorter than the species and had a tighter habit. Otherwise, the purple flowers were the same color and size as the species, and both taxa were equally floriferous. ‘Iron Butterfly’ was less prone to opening up in the center in heavy rainfall but was not untouched by this issue; damage was always more significant on the species, which was also less likely to rebound than ‘Iron Butterfly’. Powdery mildew and rust were never observed on ‘Iron Butterfly’ or the species. These taxa were the latest of the ironweeds to emerge in the spring. ‘Summer’s Surrender’ is a hybrid cross of V. lettermannii and V. arkansana made by Jim Ault at the Chicago Botanic Garden in 2010. It inherited the bushy habit of V. lettermannii and the larger plant size and capitula of V. arkansana; the olive-green linear leaves — 5 inches long and ½ inch wide — were intermediate between the two species. ‘Summer’s Surrender’ was 48 inches tall and 74 inches wide with a densely broad habit after five years, and it had a passing resemblance to ‘Southern Cross’. From early September to early October, dark purple florets, packed into 1-inch-wide flower heads, were generously produced in airy inflorescences. ‘Summer’s Surrender’ was resistant to powdery mildew and rust.

‘Summer’s Swan Song’ is a hybrid created by Dr. Ault’s crossing of V. lettermannii and V. angustifolia ‘Plum Peachy’. Similar in bushiness and fine texture to ‘Iron Butterfly’, ‘Summer’s Swan Song’ is a slightly larger plant that resists lodging because of its elongated floral branches; the interlocking of the floral branches is a unique trait that helps hold stems upright on rainy days. Deep purple florets in 1-inch -wide heads were plentiful from early September to mid-October. The feathery foliage was moderate to dark olive-green with red petioles, up to 5 inches long and less than a quarter inch wide, and disease-free. After five years in the trial, ‘Summer’s Swan Song’ measured 36 inches tall and 40 inches wide. ‘Summer’s Swan Song’ is hardy in Zone 4, despite the marginal cold-hardiness of ‘Plum Peachy’.

Worthy of more consideration

Ironweeds may be uncommon garden plants but are obvious choices for ecological and naturalistic landscapes, especially for pollinator gardens. The sheer number and variety of insects drawn to their profuse display of late-season purple flowers is astonishing. The only plant group with greater insect visitation in the Chicago Botanic Garden’s trials were mountain mints (Pycnanthemum spp.), and in particular, silvery-leaved P. muticum.

Ironweeds are often overlooked as garden plants due in part to their large size, and perhaps, being native plants, they are not readily available in average garden centers. Furthermore, the dearth of innovation in breeding and selecting new cultivars has until recently exacerbated the matter. Fortunately, the introduction of new compact hybrid cultivars, such as ‘Southern Cross’, ‘Summer’s Surrender’, and ‘Summer’s Swan Song’, has created excitement in the gardening world. Beyond the strong ornamental attributes, easy culture and adaptability to a variety of cultural conditions are merits of ironweeds.

Read the report in full at chicagobotanic.org/sites/default/files/pdf/ plantevaluation/no45_vernonia.pdf.

About the author: Richard G. Hawke is the plant evaluation manager and associate scientist at the Chicago Botanic Garden.

workstation is an area where an employee does a series of repetitive tasks; for example, transplanting, potting, patching or preparing cuttings. The layout of this area can have a large influence on the efficiency of the work that is accomplished.

Basic principles of workstation design and layout have been developed based on time and motion studies, and these have been applied to many industrial operations and tasks. These same principles can be used to improve many of the tasks associated with growing plants and often results in a 20-30% reduction in time.

Design considerations

Include these in any workstation design:

• Worktable
• Incoming materials (prefilled containers, transplants, tags, cuttings to be graded, etc.)
• Location of transplanted container (cart, conveyor)
• Space for the worker
• Container for waste material
• Tools (dibble, pruning knife)

A drawing should be made on graph paper to scale to develop the best layout. It should include the location of the worker, materials and tools.

The following basic principles should be followed:

Workstation height

The best table height is elbow height. Adjustment should be provided for different-sized workers. It is best to provide for both standing and sitting positions as greater efficiency is achieved when workers change positions.

Elbow height should be measured in the standing position. Height adjustment in the chair or stool can bring the worker up to the standing height level. Comfortable chairs with back support and footrests will create less fatigue.

Hand and arm motion

Where possible, both hands should operate as mirror images and both be working at all times. Holding something in one had while the other hand is performing a task is not very productive. If reaching for plants or other things, the distance should be the same for both hands.

Continuous or curved motions are the most natural and productive. Start-and-stop motions require more energy and time. Try to avoid lifting and instead, slide the flats.

The reach from the normal arm rest position should be limited to a 24-inch radius to the side and front for women and a 27-inch for men. Assembly area is best within 16 inches to 18 inches of the resting elbow position.

Workspace

A space of 3 feet by 3 feet is normal for the worker unless a wider work area is needed. Space to the rear should be left for movement of carts.

Adequate lighting over the work area will increase efficiency and reduce eye strain. It should be located above the workstation so as not to create shadows. A level of 40 to 60 foot-candles is necessary. Glare from lights and windows should be avoided.

Location of materials

Locate materials as close to the work area as possible. The farther you have to reach for something, the more time it takes. Walking 10 feet to get, pick up, or set down a flat will add two to three cents to the production cost of the flat.

Tipping the flat toward the transplanter can reduce the distance by as much as 10 inches. Plugs should be dislodged to effect easier removal. Locating a dibble board in a permanent holder so the worker does not have to look to retrieve it.

Prefilled containers from the flat or pot filler are best conveyed to the work area. A belt conveyor with an accumulating station works best. Gravity should be used wherever possible.

A conveyor located to the back of the workstation is best for sending a transplanted container on its way to the greenhouse. The flat or pot is just pushed onto the conveyor. Alternate locations are underneath the workstation bench or behind the worker. This involves moving or turning which takes more time. If carts are used, they should be located as close as possible to each worker.

Inexpensive fixtures or brackets can be installed to hold materials in position while they are being worked on. This frees up one hand that would normally be required for support.

Putting the above principles into practice in your operation can reduce worker fatigue and increase production output.

About the author: John is an agricultural engineer, an emeritus extension professor at the University of Connecticut and a regular contributor to sister publication Greenhouse Management. He is an author, consultant and certified technical service provider doing greenhouse energy audits for USDA grant programs in New England. jbartok@rcn.com