Water is a main point of research in the Horticultural Substrates Laboratory at North Carolina State University pertaining to its capture, retention, and availability within soilless substrates during the production of container-grown crops.

While all of these criteria are relevant, water retention and availability wouldn’t be pressing topics without water first being captured by the substrate during irrigation events.

The three properties are relatively straightforward, in that we as researchers in horticultural science are always working to improve water use and improving the sustainability and economics of plant production. The order in which these three properties of growing media are researched is not subsequent, however there must be a general understanding of how substrates are able to capture water before retention and availability are accessed.

As you know, there is a global spotlight on the use of water in the horticultural and agricultural industries, and these are driving forces behind our continued efforts to research this area.

Recent work on substrate hydrological evaluations includes the wettability and water capture of peat, coconut coir, aged pine bark and various engineered wood products. In this article, we will discuss some recent data from an experiment that included sphagnum peat moss, coconut coir, and pine bark undergoing irrigation testing to understand each substrate’s capture limitations based on the pre-set moisture levels, aka “preconditioning”.

The trial

Sphagnum peatmoss, coconut coir, and pine bark (Fig. 1) were all selected for testing based on the unique physical differences they possess. Peat is known to become hydrophobic under low moisture conditions, coir is relatively hydrophilic under all conditions and pine bark can be highly variable based on particle size and age.

To test the impacts of initial substrate moisture content (at the time of potting), we chose three moisture levels depicting different conditions at the time of potting. We tested substrates at initial moisture contents of 50% by volume (a common substrate moisture level set before potting) as well as at a lower level (dry) of 33% and upper level (wet) of 67%.

Two irrigation delivery methods (surface irrigation and subirrigation) were evaluated to better understand substrate water capture as influenced by the initial moisture level preconditioning of the materials. The surface irrigation system (Fig. 2D) is a modified surface-drip application system that has been used for substrate wettability and hydration efficiency testing for years. The subirrigation system (Fig. 2A-C) is a small-scale ebb and flood unit that was recently developed specifically for subirrigation substrate efficiency testing.

In order to create an accurate comparison of these two irrigation techniques, the subirrigation testing was modified to be under the same time-based irrigation as the surface irrigation system, with the water level kept at 2.5cm from the base of the substrate samples.

For both irrigation tests, substrate samples were packed (by weight) in clear plastic cores and then placed in their respective systems (Fig. 2).

For surface irrigation, a series of 10 simulated drip irrigation events were applied to the surface of the samples using 200mL of water at each event. After each event, the volume of water that passed through the sample was collected and measured to determine the amount of water captured during each event.

For subirrigation, the packed cylinders were placed on a mesh screen elevated off of the surface of the unit to maximize surface area exposure to the water. The unit was filled with water up to 2.5cm off of the base of the cylinder and held at that level for 5 minutes of continuous irrigation and repeated over a series of 10 events. After each event, the unit is drained over one timed minute and each sample is weighed to determine the amount of water absorbed (captured) by the substrate. For both irrigation tests, after the tenth irrigation, the samples were further analyzed to determine their maximum container capacity potentials (water holding). Data were then graphed in order to compare the results of each irrigation delivery system and as impact of initial moisture content on the different substrates.

Particle size of each substrate was also determined to help characterize each material and be able to correlate how particle size contributed to water capture (Fig. 3). Larger particles within a substrate result in larger channels for water to flow through, but fewer small pockets for water to collect and retain. With that in mind, each base substrate used had a different ratio of particle sizes to accurately understand pore size impacts on the capture and retention of water through irrigation.

Coir represented the substrate with the highest percentage of particles smaller than 2.0 mm, representing 93.8% of all particles tested while pine bark showed the highest percentage of coarse particles with a value of 53.6%. Peat occupied a middle ground between coir and pine bark with 13% more coarse particles than coir, but still 34% less than that of pine bark.

At all initial moisture levels, coir was able to take up water, however moisture content played a role in how much water was retained. Surface irrigation and under drier conditions needed four irrigation events to reach its maximum of 60% volumetric water content (Fig. 4), reducing irrigation events needed to reach higher water capture as moisture level increased to 50% and 67%. For subirrigation, coir never reached a steady-state or maximum absorption at any moisture level. At 50% moisture, coir reached a final hydration of 74% through surface irrigation and 52% volumetrically with subirrigation, never reaching its container capacity of ~75% (Fig. 4).

For peat, moisture content had the greatest influence on water capture with surface irrigation. As is well documented, intensity of hydrophobicity of peat increases at lower substrate moisture contents. These hydrophobic intensities can influence initial wetting and rewetting (subsequent irrigations during plant production) and impair the physical properties of the substrate. Regardless of moisture content, peat captured less water than that of coir, with very little water captured at 33% and 50% moisture (Fig. 4). Comparing irrigation techniques, peat captured ~20% more water through surface irrigation than through subirrigation. This is a result of surface irrigation using gravimetric pull to break the surface barrier of a low-moisture peat to channelize and hydrate the material whereas subirrigation relies on the upward wicking of water vertically through the substrate/container.

Pine bark had a more consistent increase in water captured over the 10 irrigation events than either peat or coir. Of the three substrates, bark contained the highest percentage of coarse particles (Fig. 3), while also having a similar portion of medium (2.0-6.3 mm) sized particles compared to peat, resulting in larger pore spaces for water to travel through but fewer small pores to retain that water. The volumetric water content curves (Fig. 4) identify a degree of consistency between irrigation techniques, regardless of initial moisture level or irrigation method. At 50% and 67% moisture, subirrigation produced maximum irrigation absorption after one irrigation event, with less than 2% difference between first and last irrigation event. At all moisture levels, surface irrigation had water captured after the final irrigation event compared to subirrigation, but the difference between surface irrigation and subirrigation after the final hydration was less than 10% volumetrically.

Aside from irrigation techniques and water capture, the biggest difference happens visually. Irrigating from above will always show a surface change over time to help growers identify at a quick glance whether they require additional irrigation, while frequently subirrigated containers will not show a visual color change to the container surface. But this research shows that while we may not be able to see that difference, subirrigation is allowing the substrate to still capture comparable amounts of water, depending on substrate and container type.

There are other potential capabilities of these two testing systems, with more work to come involving wetting agent application method and efficacy, evaporative water loss from substrates and non-plastic containers, and the water capture and efficiency of substrate blends formulated from numerous components, ratios, particle sizes, etc.

Study take homes

With this research showing that peat and coir capture ~20% more water through surface irrigation and only a ~7% difference in captured water through both irrigation techniques on pine bark, we can continue to progress in water conservation.

Water is a hot button topic that continues to warrant further research to continually inform growers on water management strategies and specific substrate-irrigation-crop combinations. Our industry is continuing to raise the bar in how we approach the growing concern of sustainability and addressing our water uses is going to continue to play a huge role in our future success.

Echinacea, commonly known as coneflowers, are among the most iconic and recognizable native plants in North America. The earliest documented horticultural use of Echinacea can be traced to the late 17th century when Echinacea purpurea seeds were sent to England by the Virginia clergyman and naturalist John Banister. Medicinal use dates back even further as Native Americans used Echinacea to treat a variety of ailments, a tradition that has carried into modern times.

The nine species of Echinacea are North American natives and predominantly occur in the central and eastern United States. The majority of wild coneflowers display pink, purple, and rarely white flowers from late spring to summer. Only one species, Echinacea paradoxa, breaks this color trend and produces canary yellow blooms in June.

What follows are the top-rated coneflowers for the mid-Atlantic from a horticultural and ecological perspective based on the Mt. Cuba Centers’ trials:

Echinacea purpurea ‘Pica Bella’

Echinacea purpurea ‘Pica Bella’ ranked among the top performing coneflowers in our first trial in 2009 and is again one of the most outstanding cultivars we evaluated. ‘Pica Bella’ is a compact and floriferous form of the species that originated as a seedling of Echinacea purpurea ‘Abenstem’. While many Echinacea cultivars in the market today showcase vibrant blooms that can look out of place in a naturalistic setting, the floral display of ‘Pica Bella’ resembles that of Echinacea purpurea, allowing for its effortless incorporation into a broad range of garden designs. This cultivar was also a favorite among pollinators that flocked to its prominent orange cones.

Echinacea ‘Sensation Pink’

A product of the breeding efforts of Marco van Noort in the Netherlands, Echinacea ‘Sensation Pink’ produced one of the most vibrant displays in our trial. Intense, neon-pink flowers are held on dark stems that further accentuate their otherworldly floral color. In contrast to the exuberant blooms, ‘Sensation Pink’ manifests a restrained and more compact habit relative to its wild counterparts. This cultivar was one of the five most pollinator-visited Echinacea in the trial.

Echinacea ‘Santa Fe’

Echinacea ‘Santa Fe’ is a seed-produced cultivar from the Proven Winners® LAKOTA™ Series of coneflowers.

Despite some expected variation in seed strains, Echinacea ‘Santa Fe’ showed remarkable consistency in our trial and was similar in many ways to Echinacea ‘Balsomcor’ (SOMBRERO® Hot Coral), although ‘Santa Fe’ was decidedly more vigorous. This tidy and well branched plant reaches 2 feet tall and wide at maturity. Striking coral-red flowers are produced en masse from late June through late July before eventually fading to attractive shades of pastel pink.

Echinacea ‘TNECHKR’ (KISMET® Raspberry)

Echinacea ‘TNECHKR’, also known by the trade name KISMET Raspberry, is one of several Terra Nova Nurseries introductions that were evaluated in this trial. KISMET Raspberry was a standout in the trial thanks to its strong vigor, saturated color, and oversized blooms. The glowing raspberry-pink petals are at their peak in early July and, while comparable to the blooms of Echinacea ‘Sensation Pink’ and Echinacea ‘Purple Emperor’, KISMET Raspberry maintains the slightest floral edge over these close competitors because of the sheer vibrancy of its blooms.

Echinacea ‘Snow Cone’

Echinacea ‘Snow Cone’ is an outstanding cultivar introduced by Intrinsic Perennial Gardens in Haebron, Illinois. This pocket-sized hybrid is one of the most compact coneflowers in our trial. Fully grown, it reaches 2 ½ feet in height and width, making it a perfect choice for container gardens or the front of a border. Despite its modest size, ‘Snow Cone’ puts on a first-class floral display from the middle of June through late July.

Echinacea ‘Balsomcor’ (SOMBRERO Hot Coral)

Echinacea ‘Balsomcor’, commonly known as SOMBRERO Hot Coral, is a coneflower in the SOMBRERO Series from Darwin Perennials. In our trial, SOMBRERO Hot Coral produced a compact and well-branched plant that is very similar to Echinacea ‘Santa Fe’. The individual flowers of SOMBRERO Hot Coral are some of the smallest in the trial at 3½ inches wide, but they bloom in abundance over a prolonged period from early July though early August.

Echinacea ‘Purple Emperor’

Echinacea ‘Purple Emperor’ is one of three members of the Butterfly Series from AB-Cultivars that excelled in the trial. This particular cultivar is named after a species of Apatura butterfly that is native to Europe and Asia. ‘Purple Emperor’ hybrid coneflower distinguishes itself from other medium sized cultivars thanks to its vigorous and uniform growth and its large 4 ½-inch flowers produced in late June though early July.

Echinacea purpurea ‘Fragrant Angel’

A Terra Nova introduction, E. purpurea ‘Fragrant Angel’ was the highest rated white flowering cultivar during our first coneflower trial and it remains impressive more than a decade later. The large, pleasantly fragrant, 4 ½-inch flowers present their porcelain-white petals to great effect from early July into August. Other white cultivars such as E. purpurea ‘Baby Swan White’ and E. purpurea ‘Happy Star’ have slightly reflexed petals, but ‘Fragrant Angel’ has horizontal petals that contribute to its more substantial appearance.

Echinacea ‘Glowing Dream’

Echinacea ‘Glowing Dream’ is a Terra Nova Nurseries hybrid that has incredible tropical pink blooms. A profusion of luminous flowers is held well above the foliage for six weeks in mid-June to mid-July, establishing ‘Glowing Dream’ as one of the longest blooming non-double Echinacea in our trial. This cultivar is most similar in form and color to ‘Sensation Pink’, although ‘Glowing Dream’ lacks the contrasting dark stems of the former cultivar.

Echinacea ‘POST301’

Echinacea ‘POST301’ (Postman) is a member of the Butterfly™ Series from Arie Blom of AB-Cultivars in the Netherlands. Each cultivar in this series is named for a different butterfly, in this case the Mexican and Central American postman butterfly (Heliconius sp.). This coneflower is known for its large, intensely colorful flowers and prominent dark cones. Beginning in June, showy oversized buds with attractive dark centers are held well above the foliage.

Echinacea ‘Julia’

The flowers of Echinacea ‘Julia’ are particularly noteworthy and share similar orange tones to the South American Julia butterfly for which it is named. The petals of ‘Julia’ showcase the same two-tone quality that SOMBRERO Hot Coral displays in the early season but on a larger flower. As the petals mature, they begin to express an attractive bicolor effect. The petals are a deep rosy-pink closest to the cone and vibrant tangerine at their tips. Near the end of the five-week bloom period in mid-July the flowers trade their vibrancy for soft pastels.

Echinacea ‘TNECHKIO’ (KISMET® Intense Orange)

From Terra Nova’s KISMET Series, Echinacea KISMET Intense Orange features the same breeding strategies as Echinacea KISMET Raspberry and is similarly advertised to have increased numbers of flowers and greater garden adaptability. This coneflower was often compared to Echinacea ‘Santa Fe’ and Echinacea ‘Balsomcor’ (SOMBRERO® Hot Coral) due to similarities in habit and flower color.

At Bluestone Perennials, located in rural Madison, Ohio, the last year-plus has been a blur.

Like several green industry businesses, the second-generation nursery has been slammed for the past year with more and more consumers buying plants during their extended stay at home due to COVID-19.

“It was just constantly crazy,” says CEO Bill Boonstra. “We had a really hard time keeping up for a while there. But we made it through.” Half-joking, Boonstra says the entire workforce could have just been responding to email orders and that would have kept them busy for entire shifts.

According to Boonstra – who took over the business from his father, Richard, and now runs it with his wife Sarah – the pandemic pressed on an already growing demand for the business. The company sells most of its products via a catalog, online orders and some in-person orders for local customers. In a normal year, this requires precise inventory intake, organized facilities and a flow throughout the business. During the pandemic — when in-person orders were at a halt until the limit slowly increased — this became even more important.

“We always have needed to work smart,” Boonstra says, “but it was really important in the last year or so. We were slammed all the time, hit capacity on orders and were getting called what felt like all day for orders. We’ve never needed to be on top of it like we were the last year or so.”

The importance of inventory

Dating back to the businesses’ founding in 1972 — back when the business consisted of just two rented glasshouses — inventory was done by hand at Bluestone. This isn’t an uncommon practice in any greenhouse or nursery, but it becomes increasingly difficult as a business adds space and ups its production capacity. Today, Bluestone’s inventory includes a wide variety of perennials, garden shrubs, ground cover and more.

According to Boonstra, the process involved a specific labeling for each greenhouse on the property. By going to a designated area, whomever is doing inventory or looking to fill an order can know exactly what greenhouse bay and row they are in at a given time. When the business was small, this was doable and not overwhelmingly time consuming.

However, as time went on and orders increased, Bluestone expanded well beyond its original capacity. This past winter alone, Boonstra says the business added several new structures to its facility to maintain demand now and in the future. (If another expansion comes, Bluestone does have land stretching well beyond its current structure lineup. According to Boonstra, however, there are no current plants to expand further.)

At times, demand has become so rampant that they had to stop taking orders for a day or two to catch up and get preexisting orders packed out in time. This past spring, Bluestone hit peak order numbers of around 1,800 per day. Two years ago, its peak was closer to 1,000 per day.

With the new structures coupled with increased demand, Boonstra says the manpower needed to do proper inventory by hand became too unwieldy to do efficiently. (The old marking system is still in place, however, as a backup.) The choice then became to either move workers from other departments to inventory or to try something new.

The company went with the latter option, since Boonstra believed moving workers around would only create more problems in Bluestone’s workflow. So, without a trial period, Bluestone began using inventory tracking software from Arbré Technologies, a Wisconsin-based start-up that produces RFID tracking and sensing products for various green industries.

According to Boonstra, incorporating the technology has been “fairly straightforward” at Bluestone. Each plant being tracked is stuck with a sensor tag that will then collect data from the plant and feed it back into the Arbré software for a Bluestone employee to view in an app. The sensor conveys fairly simple data such as where the plant is located on site and when it was planted. As much as a grower wants, more data can be tracked and sorted in order for the leadership team to make the best decisions possible.

“We are trying to ship faster and be smarter about it,” Boonstra says. “This and tech like it push us in the right direction.”

Empowering workers

Before installing the sensor tags, Boonstra says five employees spent their time working inventory almost exclusively. Now, that work has been whittled down to basically one person, freeing up workers to do other tasks needed or, when business is particularly busy, chipping in on inventory.

“This is freeing up some of our best people,” he adds.

Overall, empowering workers — and giving workers opportunities to thrive in the roles that interest them — is another key part of what Bluestone does. Over time, Boonstra says that it has found success by not sticking to rigid hours for workers. Instead, when they hire a new employee, they are willing to be flexible within reason.

For example: say a student at a nearby high school is looking for a part-time job, but also plays football and thus has limited hours due to practice, games and other training. Instead of ruling out that student from working at Bluestone, that student will set a work schedule around their school and activities schedule and work as much as they can. If more hours are wanted in the offseason, that’s OK too because there’s always more work to be done.

“We realized a long time ago that we needed to go to the workers directly,” Boonstra says, noting that they don’t have the luxury of being picky, being that Bluestone is located in a more rural area with a smaller workforce to pick from. “So, we offer flexibility and they will come in at a time that works for both sides and they’ll do what we need them to do for that time they are there.”

Over time, Bluestone has also made an effort to keep employees around for the long haul. This applies to a few older hourly workers who have been with the business for 10 or 15 years.

But this also applies to people who started working at the business in high school, doing something as simple as pulling weeds, filling or pulling orders that need to be shipped . When they graduate, some stay on and pick up more hours. Others head off to college and maybe pick up shifts if they are attending school locally or are home for a break. Beyond that, some even come back after college and work full-time at the business.

“We want to be a place people come back to,” Boonstra says. There are a few cases, he says, where an employee has pursued another degree altogether and then came back to work at Bluestone and make plants their career.

“It can get crazy here,” he says, “but the hope is that if we treat people right, they’ll invest in us like we’ve invested in them.”

The importance of being efficient

Every year, the entire Boonstra family – Bill, Sarah, their kids and grandkids – go on vacations to unwind and recharge. Their travels take them everywhere for a long stretch of the summer and involves hobbies such as wind surfing and hiking.

In that part of the year, the idea is to savor the earned break. All year, the entire Bluestone crew is likely busy all week and, in the case of some, working into the night. (Boonstra, for instance, will often work well past when the sun goes down and almost always works seven days a week.)

The labor required is why Bluestone has so readily embraced automation in recent years. Aside from the plant sensors, Bluestone has automated irrigation to reduce the need for labor to spend time on it. In the shipping and packing department, everything is organized in a structured system — orders are filled by one group of workers, neatly and securely packed in boxes and then sent up a conveyer belt to the shipping area where labels are printed, and orders are processed to go out.

In that space, every item has a specific home and specific package so there is no confusion about what goes where. In addition, another benefit of the tracking sensors is that plants can be earmarked for a certain order and tracked to make sure it gets to the right box. The idea is also for the process to be universal and have plants shipped correctly so that when a customer gets their order, it’s what they are expecting.

“This can get crazy — it did all last year,” he says. “So us investing in a process says us a lot of time and stress.”

Over the last few years, Bluestone has also made more of an effort to be operate sustainably. The sensors themselves can likely last several years. Elsewhere, the company’s pots are all made from recyclable material as to not use plastic and contribute to waste concerns. As Bill puts it, they know there’s only one Earth to grow on, so it’s important to do what can be done to treat it kindly.

During the busy season, Bill is probably doing a little bit of everything, while Sarah is handling a large amount of called in and online orders. Ultimately, they know that operating Bluestone takes time and effort from everyone involved. That is not lost on them when time finally does come to take a break.

“This job isn’t always easy,” he says. “It requires a lot and it likely means long days and hard work. But it’ll probably be worth it in the end when we get done and can look back at it and know we’ve earned that time away.”

Terry Leppo’s first garden was a radish patch he tended at age 7 under the guidance of his grandparents, who taught him how to grow plants on their farm in the Santa Maria Valley. Although his parents “wouldn’t touch another radish for years after,” Leppo says that this experience sparked his lifelong passion for horticulture.

“By third grade, I decided that I wanted to study horticulture at Cal Poly, San Luis Obispo,” says Leppo, who went on to earn his greenhouse management degree there in 2000. “There was nothing else I could see myself doing but growing plants.”

Now, more than 20 years later, Leppo still loves being surrounded by plants as head grower and production coordinator at Armstrong Growers, where he’s worked since spring 2015. By integrating the lessons he’s learned from his grandparents and other mentors throughout his career, Leppo continues to tweak his approach for producing beautiful plants.

“Being able to grow a crop from beginning to end and knowing that it’s going to put a smile on someone’s face is what motivates me,” Leppo says. “I’m doing my part to spread a little bit of beauty.”

Recordkeeping routine

Leppo oversees production at Armstrong’s Santa Paula and Oxnard facilities, which span 40 acres of combined production space since a recent expansion. Half of this total space is, or soon will be, under cover, he says.

His growing team is focused on producing seasonal color like annuals and hanging baskets, herbs, vegetables, potted plants and ground covers to supply Armstrong Garden Centers in addition to other IGCs, wholesale landscapers, resorts, and theme parks.

To keep operations running smoothly, Leppo works closely with his assistant grower, four section growers, and various department supervisors to closely track plant progress.

“I spend approximately 85% of my week in the field making crop decisions,” says Leppo, who walks the crops regularly to monitor plant growth, quality, and disease. “The remaining time is spent preparing for the following week’s production and upcoming crops by managing schedules, action plans, and inventories to make sure we’re hitting our goals.”

Leppo takes detailed notes about each crop to track how plants respond to various inputs and conditions — noting, for example, whether pesticide application rates cause chemical burns during certain conditions.

“We use our smartphones to capture images of diseases, insects, and symptoms on the leaves,” says Leppo, who compiles these notes and pictures into Excel spreadsheets that his growing team can reference throughout the year. “By reviewing these notes prior to each season, we’re able to make adjustments and avoid repeating mistakes.”

Demonstrating benefits

Training is another factor in achieving consistency and continuous improvement at Armstrong Growers. Although the growing team contains plenty of experience — one of the growers has been with the company for 25 years — Leppo still gathers them for regular training reviews.

“When we come to the new season of a crop, I like to get everyone together and demonstrate our processes as a seasonal reminder,” he says. “For example, we’ll review proper planting depth and placement for poinsettias. They can ask questions and plant samples to make sure they’re doing it correctly.”

The key to Leppo’s training approach is not just explaining what to do, but why. Instead of just demonstrating how to properly pinch poinsettias, he explains why the pinch height should include the correct number of nodes, because too many flowering stems could cause the plant to break under the added weight.

“Why we do something is just as important as how to do something,” he says. “By explaining the why, it instills pride, responsibility, confidence, and ownership in your employees. When you take the time to explain the why and demonstrate the procedure, the outcome is quality and consistency.”

Improving over time

Leppo is constantly tweaking his programs to improve crop quality. For example, his pest management methods have changed through the years — most recently merging into what he calls a hybrid approach of both biological and chemical controls.

At the start of poinsettia season, he relies on biological controls and beneficial releases to reduce whitefly pressures. Then, if the plants need stronger defenses during the flowering stage, he’ll introduce the required chemical inputs.

“Overall,” he says, “we’re able to cut the amount of chemical controls we use. There are definitely benefits to that, because it’s safer for the environment, for the plants, and for our employees.”

Since he hasn’t produced his “best poinsettia crop yet,” Leppo is committed to keep improving until then.

“I’ve been in the industry over 20 years, but I don’t think that I know everything. If I shut myself off with the mindset that I don’t have anything to learn, then I’d be missing out, and so would the company,” Leppo says. “I’m very proud and fortunate to work here, where employees at every level of the organization strive together to grow beautiful products and make customers happy.”

The author is a freelance writer based in Cleveland.