With about 10 acres of production under cover and 4 acres of outdoor space, SunBlest Gardens in Crawfordville, Florida, grows Boston ferns, liriope, multiple spring bedding plants, mums and poinsettias.

Because of the Sunshine State’s warm and humid climate, SunBlest grows for 10 to 11 months of the year. Through these extended seasons, head grower Jared Jent and his team require pest and disease control and prevention, as well as compact growth. Over the past several months, they have achieved desired results using a few SePRO products.

Preventing diseases with Obtego

Jent began trialing the SePRO’s Obtego Fungicide and Plant Symbiont on mums and poinsettias in the summer of 2019 to see how it would perform in helping prevent diseases such as Pythium and Phytophthora.

In Crawfordville, temperatures were around 90o to 100o F for much of the summer, Jent says. “Most of my biologicals are really stressed during that time, but Obtego continued to work during the entire time,” he says.

SunBlest Gardens direct-sticks mums in May and June, then moves them into its finished area two to three weeks after propagation. A trial of a one-time, 5 ounces per 100 gallons of water drench of Obtego on 5,000 to 6,000 mums helped keep the crops healthy.

Obtego contains unique strains of Trichoderma asperellum and Trichoderma gamsii, which according to Jent, are two species that attach to plant’s roots and promote root growth. “Plus, there’s beneficial fungi to help pick up the nutrients, water,” he says. “I’d say you just have more root area, and therefore you have a healthier plant.”

As with its mums, SunBlest drenched Obtego on poinsettias after transplant and saw promising results.

“When you come with the biological, then you have this relationship in the soil that’s thriving, so you don’t have to continuously come back with your synthetics every four to five weeks,” Jent says. “We see that as a good thing because if you’re [applying] a one-time drench, your roots are thriving; these Trichodermas are thriving. We can see this relationship in the pot with all the colonization.”

Increasing compactness with Topflor

To control the growth of poinsettias and spring bedding plants, Jent uses SePRO’s Topflor Plant Growth Regulator.

On poinsettias, SunBlest applies a 0.2 parts-per-million (ppm) drench directly after transplant, then about a 0.1 ppm drench in October and a 0.1 to 1 ppm drench in November.

“I always recommend the one right after propagation, and that’s a nice toning [application],” Jent says. “The plants look good after that — it strengthens them. Then October is when you just have to look at your graphical tracking and decide how much you need to increase or decrease on your plant height.”

In Crawfordville, temperatures can still be 80o F as late as November, Jent says. Because of this, SunBlest uses higher PGR rates than growers in other parts of the country.

As with other PGRs, Topflor reduces poinsettia height and improves performance. And while Jent says he has experienced bract size reduction with another PGR, he hasn’t had that experience with Topflor.

“You can [overapply PGRs on] plants, then you get this really kind of crunchy-looking growth just because you have too much PGR on it and it just looks real tight, versus with Topflor we don’t see so much of that tightness,” he says.

SunBlest’s 2020 spring bedding plant production has also benefited from Topflor. “We’re seeing the nice, toned look,” Jent says. “The plants are not stretching.”

Controlling whiteflies and chilli thrips with Rycar

For whitefly and chilli thrips control, Jent rotates Rycar Insecticide from SePRO to prevent insecticide resistance. For both pests, he sprays a rate of 3 ounces per 100 gallons.

Throughout poinsettia production in 2019, Jent says SunBlest made about four to five applications of Rycar and saw whitefly populations decrease.

“If you look at your sticky cards and look at your population, do a spray, check a few poinsettias, you do not see very many after a Rycar spray,” he says.

Jent says Rycar has curative properties that allow growers to cut down a population if it has recently increased.

“Also, you can spray it on bracts, which is pretty big,” he says. “Before ship, we can go and spray [the crop] with Rycar and have no phyto on the bracts and they’re good to ship.”

So far in 2020, SunBlest has seen positive results spraying Rycar on chilli thrips, following the same application rates and timings as it followed when controlling whitefly on poinsettia.

Overall, Jent says his use of SePRO products has been a success. “At the end of the day, when you have to make a choice about what to spray, it’s [about] what you feel the best about spraying,” he says. “I think all those products are good choices. They’re definitely products that you want to put out there. If you’re going to put your time and effort into something, then these are the products that I would choose.”

When Bill Turner started working in the greenhouse industry more than 40 years ago, there were no computers, no internet resources and very few growers willing to share their expertise.

“You either learned by reading or you learned from hands-on experience, so you were really dependent on the knowledge of those above you,” says Turner, head grower at Van de Wetering Greenhouses. “When I was younger, most growers were not forthcoming with knowledge. Everybody liked to hold on to what they’d learned, and they were resistant to pass down what they knew.”

When Turner was in high school, he got a job working at the greenhouse that his father managed in New Jersey. He was growing potted mums when suddenly, one day, the holiday department manager quit — taking all his notes, records and career knowledge with him.

“It was an eye-opening experience,” Turner says. Although he paid enough attention to keep the holiday department running without any major hiccups, that situation taught him how important it was to foster a smooth knowledge transfer between generations of growers.

Ever since then, Turner has been thoroughly committed to sharing his expertise.

Learning from mistakes

Turner went to college to be an accountant like his mother but followed his father into horticulture instead. “I fell in love with the job because I loved growing plants,” he says.

In 1985, Turner started working at Ivy Acres, which was founded by brothers Jack and Peter Van de Wetering. After Peter started Van de Wetering Greenhouses to produce plugs and other plant material, Turner started there as head grower in 1992.

When Turner first joined the company, Van de Wetering Greenhouses produced about 50 million plugs a year. As head grower, he did everything from seeding to growing to shipping — with plenty of experimentation along the way.

As the company grew, Turner’s role gradually evolved from grower to mentor. Today, he manages one assistant head grower and three section growers, along with a cross-trained team that helps care for plants in Van de Wetering’s 20-acre facility on Long Island.

“I learned that you can’t do it all yourself,” says Turner, who oversees production of about 250 million seedlings and 30 million cuttings a year. “Now, I do a lot more mentoring than I did early on, because you have to prepare the next group of growers to be able to do what you do. The benefit they have is I’ve made a ton of mistakes and I’m able to pass those on.”

For example, Turner admits he was heavy-handed with trial applications of new plant growth regulators early on, which stunted entire crops of poinsettias and New Guinea impatiens cuttings. From those mistakes, he learned to do multiple applications at lower rates.

Passing down knowledge

Many years ago, Turner started documenting his mistakes and lessons into a growing guide for his team. By developing and continually updating this manual of plant knowledge, Turner hopes to equip his growers with everything they need.

“We started with the crops we struggled with, like getting bacterial leaf spot on verbena because we weren’t feeding them enough under the high-pressure lights. So, if you’re taking care of the verbena seedlings, you know exactly what to do fertility-wise, how to weigh the trays to determine if they need water and what chemical applications to do,” he says. “You have the knowledge right in front of you, so you don’t have to keep asking the same questions. There’s no secrets, no hidden knowledge here.”

The guide is available in English and Spanish to accommodate Van de Wetering’s bilingual workforce. Turner updates the information almost daily as he continues to troubleshoot issues and grow more efficiently.

For example, he’s started using biological pest controls to cut down on chemical applications.

“The only way you can get better is to look at what you’re struggling with and work on your weaknesses,” he says. “You can never be complacent in this business.”

Turner says growers today have the advantage of the internet, enabling them to connect with other growers on social media and Googling issues to find solutions.

But he still says that social media doesn’t replace hands-on learning. “It still comes down to walking through the crop and being able to handle problems before they happen,” he says.

As satisfying as it feels to master a crop, Turner says it’s even more gratifying to teach young growers how to do it themselves.

“That’s what gives me the most passion now is teaching and mentoring the younger guys, because when I was young, not everybody wanted to help,” he says. “Growing is hard, so it’s nice to be able to help people out and save them from the pain you’ve had in your life.”

Photo: © inueng | Adobe stock

Tropical houseplants and “plant parenting” have been trending for a while now and by the looks of it, their stars will continue to rise in 2020. Tropical houseplant sales undoubtedly contributed to the rise in garden industry spending (up to a record $52 billion in 2018, according to the National Garden Bureau), but they also marked the increase of Millennials’ participation. Younger garden and houseplant consumers, who made up 25% of the customer base in the same study, now rival plant and garden spending by Gen Xrs and Boomers. As the market shifts, how do you shift?

Retail shift

There’s no apparent slowdown in non-green industry retailers getting into the houseplant-selling game. As I am writing this column, I just read that the furniture retailer West Elm will be selling houseplants online, courtesy of fulfillment by Bloomscape. Their selection will be limited to pretty much the same handful of tropicals that most other new online plant shops are offering, but it’s a move worth noticing.

Here’s the reality: Independent garden centers just do not want to retail online. Or, they just can’t seem to figure out how to even do so if they want to. Many are so far behind the game that I’m not sure they’ll catch up at this point. This reluctance to go digital has meant that IGCs have given up a good piece of market share to all of those new online houseplant vendors.

So how do you, as a grower, capitalize on the houseplant boom and move volume if your IGC customers just aren’t ordering enough from you? Like many other wholesale growers, you may be considering the shift to direct-to-consumer sales, if you haven’t already (see my last column on direct retailing: here). Or, you may consider making a fulfillment deal with a retailer — like what Bloomscape did with West Elm — so they bear the consumer-facing marketing burden. Either way, there is still plenty of wiggle room for boosting your tropical sales.

Focus on foliage

First, let’s pay attention to what’s already getting our customers’ attention. There is a serious focus on foliage color and form, specifically pink foliage color, variegation and unique leaf shapes. This includes the shadows and shapes a leaf will make in a space with different lighting. I’m not kidding. Leaf shadows are a big draw for customers who buy specimens of Monstera adansonii. Essentially, how a plant will add to and complement the aesthetics of one’s home is a top priority for many younger houseplant enthusiasts. Plants are pieces of living sculpture that adorn the plant parent’s home.

Plant priorities

While Gen X and Boomer customers tend to prioritize ease of care or low-maintenance houseplants, younger customers are prioritizing collecting unusual or rare species or varieties. They are willing to pay hefty prices to do so. That’s not to say, however, that they don’t eventually bail on specimens they find particularly difficult to maintain indoors. Succulents saw a big boost in popularity over the last few years, but it was accompanied with a high failure rate for many indoor growers without grow lights. Once a plant keeper realizes they need a grow light setup, then back to succulent and cacti collecting they may go.

The struggle is real

Speaking of grow lighting, and to follow up on my column from December (bit.ly/GM-grow-lights), indoor light, and where to place plants for best light access, is the biggest struggle for most houseplant keepers. That struggle puts them on the hunt for low-light plants that can handle their existing conditions. Even so, many new customers are also willing to shell out for artificial light setups to keep their houseplants happy.

Let’s take the light issue one step further: Considering how much time I spend these days explaining PPF, PPFD and DLI to amateur houseplant hobbyists, it might be time for the green industry to get much more clear about the lighting needs of each houseplant species when creating label copy. General light recommendations just aren’t cutting it.

More grow light manufacturers are finally starting to put meaningful PPF and PPFD output information on their packaging (versus lumens or foot-candles), so why aren’t we putting relevant quantifiable light volume requirements — such as DLI ranges — on plant tags? I realize that’s going to take a lot of new research to pinpoint this information for groups of tropicals and succulents, but I don’t see this information as any less important than USDA Hardiness Zones for outdoor garden plants.

So, who’s ready to start up an indoor houseplant light trials program?

Hot plants

The hot plants for 2020? I’m sure there will be many. While Pilea peperomioides held the top spot in 2018 and into 2019, philodendrons and Monstera have moved in to take the crown. Monstera adansonii seems to get the most attention and Monstera deliciosa is also holding strong. Less common philodendrons or pink foliage cultivars are selling strong. Rhaphidophora tetrasperma is in hot demand and low supply. I suspect money trees, Pachira aquatica, are set for a comeback. Unusual succulent specimens are still capturing fancy, and it looks to me like orchids are poised for a resurgence of interest.

And of course, I’m certain that teeny tiny cute tropicals are prime for a moment in the spotlight. So, if you have any new tiny cuties you need the world to see be sure to let me know, because I’m masterminding my new tiny plant collection as I type …

Photo courtesy of Christopher J. Currey

Reducing phosphorous (P) during plug production has become a standard practice to control growth. However, this technique does not need to be limited to plugs. Rather, recent research is showing that reducing P during finishing for containerized crops can control unwanted stretch while producing marketable plants.

P₂O₅ versus P

Before discussing P further, some clarity is required. On fertilizers, the concentration of P in fertilizer analyses is the concentration of phosphorous pentoxide (P₂O₅), not strictly P. Elemental P is actually 43.7% of the weight of P₂O₅. So, a 20-10-20 fertilizer is not 10% P by weight, as we commonly think; rather, it is 10% P₂O₅ and 4.37% P by weight. Similarly, a fertilizer solution providing 200 ppm nitrogen (N) is not providing 100 ppm P; it is actually providing 100 ppm P₂O₅ and 43.7 ppm P. By multiplying P₂O₅ concentrations by 0.437, the true or elemental P concentration is determined. Conversely, the P₂O₅ concentration can be determined by dividing P concentrations by 0.437.

Reducing phosphorous during finishing

When 150 to 250 ppm N is provided from fertilizers such as 15-5-15 or 20-10-20, the amount of P provided to plants ranges from approximately 22 to 55 ppm. This is more than enough P to produce healthy-looking plants, and these concentrations also maximize growth, including stem elongation.

By providing less P to plants, there is less stretch and stem elongation (Fig. 1); however, P concentrations must be enough to avoid unwanted symptoms of P deficiency, which may reduce marketability. For example, P concentrations between 5 and 10 ppm P can control growth and produce healthy-looking plants with no P deficiency symptoms for a number of annual bedding plants and flowering potted plants.

For many plants, P cannot be completely eliminated during finishing and 2.5 to 5 ppm P should be provided to sustain acceptable growth and appearances. However, we have seen some crops, including some vegetatively propagated crops and large dormant perennial plugs, grown to flowering with no P and have seen positive results. More than likely, there is sufficient P stored in the rooted cutting or perennial crown to suffice for the plant after transplanting and throughout finishing and forcing. For seed-propagated plants, the P content of a seedling plug is much less than a rooted liner and is not sufficient to carry the plant through production.

Though the focus on reducing P is for controlling growth, there are other potential benefits to reducing P during production. For example, P is one of the most easily leached nutrients from soilless substrates in production. By reducing the amount of P applied to crops, the amount of P entering waterways is also being limited.

How to provide less phosphorous

There are several ways to reduce the amount of P provided to plants in the greenhouse. One of the easiest ways to do this is to provide less fertilizer. Since most water-soluble and controlled-release fertilizers are complete with all macronutrients, including P, using less fertilizer inherently provides less P to crops. However, in using less fertilizer, the amount of other nutrients provided to plants is less. This may be problematic, and insufficient amounts of other nutrients may be provided.

Selecting a fertilizer with less P relative to other nutrients is another way to provide less P to crops. For example, a 20-10-20 fertilizer provides half the amount of P compared to a 20-20-20 option. But there are other fertilizers that provide even less P relative to N. For example, fertilizers such as 21-5-20 and 13-2-13 provide lower amounts of P relative to other nutrients, so less P can be provided without reducing the amount of nitrogen or micronutrients provided. However, when using a complete fertilizer like these for your P source, the P is still tied to the fertilizer concentration.

The most flexible way to control P provision to containerized plants is to use a source of P independent from the primary fertilizer. First, select a fertilizer without P, such as 20-0-20 or 15-0-15. Then, use a separate fertilizer to supply P, such as monopotassium phosphate (MKP; 0-52-34). This can either be tank-mixed with the stock solution of your primary, P-free fertilizer or it can be injected separately through a second fertilizer injector.

By separating out P from the other macro- and micronutrients, you can limit the P provided to plants without potentially limiting other important nutrients.

Take-home message

At the N concentrations commonly used for finishing containerized crops, growth-saturating amounts of P are also being provided. By reducing P concentrations during finishing, growth can be controlled without P deficiency symptoms. There are several approaches to providing less P, and a potential solution for any producer should be among them.

The author (ccurrey@iastate.edu) is an Associate Professor in the Department of Horticulture at Iowa State University.