Your smartphone may be a distraction from greenhouse duties — or perhaps it’s a way to productively check email or complete general business-type tasks. Usually, you would not use it as a tool to monitor plant nutrition levels. But now, that is changing, as researchers are working on a way for growers to use their smartphone to measure plant nitrogen.

Krishna Nemali, assistant professor of controlled environment agriculture at Purdue University, is working with this technology. Using a microcontroller (small computer) called a Raspberry Pi attached to cameras, filters and a casing, and either a smartphone or computer, he says a grower will soon be able to affordably take photos of multiple plants at once and receive a quick reading of how much nitrogen is in them.

“We use actually two cameras with nitrogen measurement because we are picking crop signature,” Nemali says. “People say ‘crop signature,’ but it’s basically what plants are telling us — they’re talking to us in a different language. We are picking up that signature and using the signature, we can actually indirectly measure how much nitrogen is there in the plant.”

The evolution of nitrogen measurement

By measuring nitrogen and applying proper nitrogen amounts, Nemali says growers can keep their plants healthy, save money on fertilizers and be responsible to the environment by avoiding runoff.

“What matters is, at the end of the day, how much of that fertilizer ends up in the plant — not how much you supply to the fertilizer solution, not how much is in the substrate — but what is inside the plant is what matters because that is what is used in the growth and making a good-quality plant,” Nemali says.

He points out there are currently four generations of techniques growers use to measure nitrogen.

The first generation is simple. “You’re walking and you’re looking at these plants; ‘Oh, these plants are small.’ You’re sensing something visually,” Nemali says. “But there are a lot of errors associated with that.”

The second generation involves cutting and harvesting plants and sending them to laboratories. It could take seven to 10 days for those labs to return results and multiple samples are often required at $20 to $25 per sample.

The third generation includes electrical conductivity sensors, quantum sensors and other technologies that are both useful and popular, Nemali says. But growers can only measure one pot at a time.

Enter the fourth generation. “Now, we are moving into something called remote-sensing — plant-based, imaging-based sensors,” Nemali says. “This is the most advanced sensing, and I think our industry needs this, and that’s what I am after.”

Remote sensing

Purdue’s devices, which include cameras, Raspberry Pis and other accoutrements, will likely cost about $150. Nemali says this price is well within the range of what studies show many people are willing to pay for beneficial technology.

Following their purchase of one or more devices, growers can manually take photos as they walk through the greenhouse, from multiple stationary devices around the operation or from irrigation booms and other moving objects.

From there, growers can send photos to a smartphone or computer. Currently, Purdue University uses a server to process the images and estimate nitrogen levels in plants, then sends the information back to the growers’ smartphones or computers.

“They can actually take these measurements as many times as they want in a day or every day,” Nemali says. “It’s just like taking a picture and sending it to someone, like texting an image.”

Compared to laboratory analysis of nitrogen content, the researchers are getting similar nitrogen reads through image-based estimation.

They can actually take these measurements as many times as they want in a day or every day. It’s just like taking a picture and sending it to someone, like texting an image. — Krishna Nemali

“What we are seeing is that there is a near-lineal relationship,” Nemali says.

The university developed algorithms to estimate the amount of nitrogen in plant tissues, by using hundreds of samples from bedding plant and poinsettia species.

In the future, Purdue will also develop an app for growers to estimate nitrogen content and bypass the need for a server, Nemali says. Using the app, growers will select a species — at times, a specific variety, get a reading of the amount of nitrogen in the tissues of their plants and fertilize the right amount of the nutrient to their crop.

The Horticultural Research Institute, American Floral Endowment and Fred C. Gloeckner Foundation are all funding Nemali’s project, which he notes is not typical. All three groups are large and focused on applied research, which Nemali says indicates that the greenhouse industry is looking for smartphone-based technologies.

Most of the funding from the Gloeckner Foundation went toward working on algorithms and software for poinsettia nitrogen estimation. AFE funding is going toward developing models and algorithms for bedding plants and 2019 HRI funding is being spent to build devices and distribute them to growers.

In 2019 and into 2020, Purdue will perform beta testing on the project. Growers will need a smartphone with mobile data to participate in beta testing, and they will receive the additional hardware at no cost.

“We are looking for some of those growers who are really into technology — it doesn’t matter what scale it is — but who can actually collaborate with Purdue all over the country,” Nemali says.

The demand, use and need of growing media worldwide is increasing due to the increased production of plants in containers and controlled environments. An industry that once primarily served the floriculture and ornamental nursery industries now serves a booming industry of container-grown vegetables, cannabis, herbs, leafy greens and small/soft fruit. The future is very promising and strong for the continued need of various growing media components as more and more countries become more advanced in growing crops in containers, and as more and more different (both new and traditional) crops around the world begin to be cultivated in places other than the field.

With increased demand and use comes increased interest by some to recycle or reuse their growing media, otherwise it has to be disposed of in some way. A practice that is as old as our current greenhouse industry, the reuse or repurposing of growing media has been met with rewards as well as some serious challenges by different individuals. While searching the scientific literature, trade magazines and online sources, I began to quickly realize the scope of what is known, not known or believed regarding the pros and cons of reusing growing media. The following terms occurred multiple times as I searched this topic: reduce, reuse, recycle, reutilize, rehabilitate, reclaim, repurpose, restore, regrind, recondition, replace, reduce, reprocess, repeated, reapplied. I never knew there were so many synonyms for reuse! With this being stated, let’s take a quick look at some of the various pros and cons of reusing organic growing media. The reuse of inorganic materials (rock/mineral wools, perlite, pumice, clay pebbles, etc.) deserves a separate and more thorough discussion of their own as they have potentials, reuses and issues much different than the organic materials.

First, some terminology. As is often the case, nomenclature of a topic can often be confusing and words or concepts used interchangeably when they should not be.

• Sterilization — the temporary destruction of most all living organisms including microorganisms, bacteria, fungi/spores, nematodes, insect eggs, weed seeds, etc. using heat of at least 212°F for at least 30 minutes.
• Sterile — free from most harmful pests or diseases commonly problematic for cultivated plants. Can be achieved without steaming/heating and does not eliminate all microorganisms/biology in the soil/substrate.
• Sanitation — a condition, situation or environment that is free of harmful pests.
• Solarization — the use of the sun’s energy to heat soil/growing media that is covered in a transparent polyethylene tarp and allowed to heat to at least 160°F. This can be for short time, 30 minutes or over the course of weeks, depending on the setup and operation (Fig. 1).
• Pasteurization — a process of making something free from most forms of bacteria, microorganisms, diseases, weed seeds or other forms of life. This is typically achieved with steaming to a temperature of about 180°F for 30 minutes.

Growing media can be essentially sterile without being sterilized or pasteurized. Peat moss for example, contains many natural beneficial microorganisms, therefore not technically sterile, but it typically contains none that are harmful to plants grown in the moss. Sterilizing peat moss would destroy the beneficial organisms, thereby reducing the quality of the peat. Also, by virtue of where peat originates, it is not prone to have weed seeds or contain insect eggs/larvae, or other potential pests that would harm horticultural crops. The same can be said of many of the commercialized wood fiber products currently on the market.

Many growers may not have the need to dispose of or recycle growing media if all of their crops are container-grown and shipped out or sold. An exception may be the need to dispose of unsold, damaged or poor quality plants that often get piled outside somewhere on the property. These “death piles” can be seen at many nurseries and greenhouse grower operations across the country (Fig. 2).

It is also important to note that even if recycled growing media (or soils) are sterilized to remove all potential pests, it does not mean that the materials will remain sterilized. Sterilization of any material is only a temporary state or condition. If pests or diseases are present in the potting or production area, they will be re-inoculated quickly.

Potential risks

Recycled growing media can have some detrimental properties that should be considered and monitored. First is the potential loss of physical properties of reused media. Over time, organic particles naturally break down (decompose), thereby decreasing structure and air porosity. If materials are ground up or otherwise handled during sterilization processes, the particle size will continue to reduce, therefore changing the physical properties when repotted. Blending in some percentage of new growing media with the old/reused would likely help with this problem.

Secondly, reused growing media can house potentially harmful pathogens, pests and other unwanted goodies if not properly sterilized or treated. The infection or exposure that improperly recycled materials can have on a grower operation can be very detrimental to future crops and cropping cycles. Recycled materials left outdoors can easily be contaminated with weed seeds (Fig. 3) and or pathogens. Recycled materials not properly sterilized could contain Pythium, Fusarium, Phytophthora and other plant-sensitive diseases. The recent increase in legalized cannabis production has also exposed new biological concerns (many may be unfounded) including the presence of E. coli and Salmonella in growing media that are now being monitored and, in some cases, regulated for.

Lastly, there can be some toxicity effects from reused growing media. Mostly in the form of residual fertilizer salts that can create high EC in mixes when re-blended or reused in future crop productions. This can alter fertility practices and management as well as crop growth response and control. Desalinization via washing or flushing with hot water is needed to remove potential salts from materials like coco coir.

Potential rewards

If done properly and monitored, the reuse and recycling of growing media can save money for some growers if they are willing to invest the time and resources to properly do it. Growing media is often not cheap, so it is possible to save some money. Reuse of materials is also a great way to reduce the disposal of organic and inorganic materials, and make operations more sustainable and carbon-neutral. Some cut flower growers and others have the process of recycling their growing media down to a science and have been very successful for many years incorporating it into their growing systems (Fig. 4).

With all of the “re-” words listed in the beginning of this article to describe growing media, the one that should be considered and remembered most is re-spect! Your growing media is such a vital part of the success of your production system, be that large or small, professional or hobby market. If you reuse or recycle, do it right and understand the potential consequences. Cutting corners or trying to save a dollar may be worth it on some things, but do not jeopardize the quality and performance of your growing media! Your plants will thank you.

The author is an associate professor and director of the Horticultural Substrates Laboratory at North Carolina State University. He can be reached at Brian_Jackson@ncsu.edu

Fads may come and go in the beer market, but there’s one thing that stays the same: People like beer. But as drinkers reach for beers more on the bitter side (think IPAs), a whole new world of opportunity is opening up in the hops market.

Hops are what give beer that balance and depth, as well as their bitterness and aroma. And as craft brewers experiment more and more with them, all kinds of new options are hitting the shelves.

Traditionally grown outdoors in the Pacific Northwest, hops are making their way into greenhouses as brewers search for fresh, local ingredients. And while much of the indoor growing is still in a trial or preliminary phase, it could just be a profitable addition to traditional greenhouse crops. You can read more about greenhouse hops pioneers in our cover story, along with developments in research and marketing ideas.

And it’s not just that IPAs are having a moment in the sun. Craft brewing has gained momentum over the years, and just as people are opting for locally grown produce, they’re reaching for locally sourced beer as well. Like the local food and farm-to-table movements, consumers are looking for ways to lower their carbon footprint while improving the quality of their food and drinks.

It's a trend we see in gardening too. As the market for native plants continues to thrive, looking close to home for solutions is becoming more and more popular. And while it’s tough enough to know your costs and where profits lie with your current offerings, it never hurts to look into something new and different.

The key, like with any trend, is to know your costs, know your operation and know your what your customers (or potential customers) want. If there’s a certain kind of hops brewers in your area are dying to find, you could be their solution.

If you’re looking to expand, it’s always a good idea to keep your ear to the ground and stay open to new possibilities. With the right research and development, you just might find success in a market you never thought of entering.

Over the past two decades, Cindy Drumgool has seen changes to the mum market, but one thing has remained the same: Mums are a staple fall crop for greenhouse growers.

“When you think of fall, you think of mums, which set the stage for all of our favorite fall activities,” says Drumgool, who has worked with mums for more than 20 years, first as a grower at a commercial operation in Massachusetts and now as mum business manager at Ball Seed.

Growing tips

According to Drumgool, one of the top keys for mum production is to fertilize the plant early in the production cycle. “Mums are heavy feeders, so it’s important to load the plant [and] be able to provide the nutrients the plant needs throughout the growing processes,” she says.

Additionally, for growers propagating mums, Drumgool says it’s important to keep the cuttings warm. In areas where temperatures drop below 70°F at night, mums can sometimes initiate flowering earlier than normal, with crown budding occurring. When that happens, the plant may no longer be on the ideal growing schedule. Oftentimes, depending on when a grower is planning to finish their mums and get them to customers, this can be early in the season, when cool nights are still occurring in May and June.

“At that time, growers are cooling their greenhouse and not even worrying about having to heat,” Drumgool says.

Current market trends

On the market right now, Drumgool has seen a trend toward families of mums — plants with similar color and size that can be grown together.

“It’s something we are working on with the breeders we work with, it’s really important for growers to have access to a series of colors that grow and time the same, and can be grown in combination,” she says. “You see more and more trends with patio pots and combos. Homeowners want easy ways to decorate the outside.”

Coming to market for 2020, Drumgool says, is Zuma Orange — a mum popular among trials. It is a striking deep orange with a darker center.

“It showed excellent heat tolerance with no heat delay and has performed really well in blackcloth trials,” she says. “That’s an early variety in the north. It features limited fading too.”

Another popular new mum called Hot Sugar Gold Bronze is a late-season variety with golden-orange to bronze coloring and a mounded growth habit ideal for landscapes, Drumgool says. Two other standout options are Kizzmet Golden Yellow, an early-season variety ideal for landscapes, and new Trickster Golden Bronze, a mid-season variety that is golden yellow to orange bronze and is more golden in high heat and has a mounded growth habit. In non-fall colors, Whispered Lavender and Skye Pink are two standouts.

Bringing mums to market

Drumgool says it takes at least three to four years for a new mum variety to reach the market because breeders will present a large batch of mums to test in the first year of development. From there, trials help narrow down the list of mums that may eventually become available to growers. According to Drumgool, it’s important to take the necessary time with this process because some varieties will perform well where the breeder is based, but will do poorly in trials where a potential grower is. Oftentimes, she says, trials occur in Europe before they even reach the United States.

“It’s asking, ‘Do we see here what they saw at trials in The Netherlands?’” Drumgool says. “That’s the first test — to see if it has good keeping quality, good color, that it doesn’t split, performs well throughout the growing season and it blooms at a proper time.”

If a variety makes it into year two, Ball evaluates the plant in more detail to see if it fills a gap in its mum program, fits into a certain family, and/or would be an upgrade on a plant currently in the program.

“That’s a very small group of product,” she says. In years three and four, the plants will be introduced into tissue culture to grow stock plants. Then, the chosen plants are listed as new varieties and as available in small quantities for growers to try as Ball collects more data on the plant.

“We want a plant that’s going to have good keeping quality so it performs well not just for the grower, but the retailer, the landscaper, the end consumer,” she says. The main characteristics Drumgool says Ball values are keeping quality, disease resistance, habit and uniformity, no heat delay and excellent overall performance.

As for colors, she says the most popular colors on the market are the standard fall ones.

“Yellow is the most popular, along with the oranges and the reds,” Drumgool says. “What we have seen is the purples are becoming more popular in color and the pinks are less so. If the growers have a choice, they tend to prefer the purples over the pinks.”

For more information, visit ballseed.com