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

From baseball games to backyard cookouts, beer is a summertime staple in the U.S. But you might be surprised to find how much time, effort and money is involved in growing just one brew ingredient: hops.

Easily growing up to 20 feet tall, hop plants require labor-intensive training, trellising, pruning and harvesting, which can also call for specialized equipment. And when hops receive too much heat, or don’t obtain enough light, greenhouse hop growers turn to shade curtains or supplemental lighting — more added costs.

But demand for hops and starter hop plants is prompting some craft brewers and hobby home brewers to purchase products from greenhouse producers.

Jon Vanden Heuvel, vice president of Sandy Ridge Farms in Zeeland, Michigan, supplies starter hop plants to finished growers, who are in turn, growing and harvesting hop cones for brewing. As a greenhouse manager and former home brewer, he ventured into growing hops around 2006 during a hop shortage in the primary hop-producing states of Washington, Oregon and Idaho.

“That’s when the hop production industry in Michigan and in the Midwest started to take off, because the Pacific Northwest wasn’t producing to the demand at the time,” he says. “It was kind of right place, right time. I learned that I was better at propagating plants than I was at growing them in the field, so we moved it into the greenhouse and started to market starter plants to the farms that were going in in Michigan.”

Now Vanden Heuvel ships an estimated 100,000 plants a year — sometimes more — regionally, nationally and internationally to finished growers. In some cases, he can trace hops harvested from his plants, once they fully grow and are harvested by one of his customers, to specific craft breweries such as West Michigan’s Bell’s, Founders and New Holland.

Sandy Ridge Farms has 110,000 square feet of greenhouse production space, including about 20,000 square feet for hops production and 5,000 for hydroponic lettuce. Ornamental perennials such as hostas, daylilies and clematis make up the rest of the greenhouse’s production.

Vanden Heuvel grows his 3- to 6-inch-tall hop plants in the greenhouse, scattered throughout the rest of his production. He controls the environment similarly to his ornamental perennial production.

A few years ago, the company transitioned from growing annuals to perennials. When they were growing annuals alongside hops, they ran into production issues with heat.

“Hops are a plant that will grow a foot a day, so the cooler you can grow it, the more controlled it is,” Vanden Heuvel says.

Sandy Ridge Farms propagates its starter plants using green cuttings from stock hop plants. The operation has had field-ready plants in eight to 12 weeks, but usually allows about four months to produce them.

“Ideally, we’re doing the cutting and the sticking in the summer, and then the guys are planting them in the spring,” Vanden Heuvel says. “That gives them that winter to vernalize in the greenhouse.”

Hop production techniques

Sandy Ridge Farms acquires its stock plants from the USDA’s National Clean Plant Network out of Prosser, Washington, and follows strict sanitation protocols. The operation propagates roughly 50 varieties, including USDA’s new Triumph variety, which it will begin selling in July.

“Starting seed with hops is incredibly rare, and it’s also rather difficult,” says Brian J. Pearson, assistant professor of environmental horticulture at the University of Florida. “Getting them from rhizome has been the traditional way of getting it.”

But he tells growers who have an interest in producing hops to consider tissue culture propagation so they can bring in a disease- and virus-free product, and have consistent parentage.

As with other crops, it takes effort to control viruses, pests and diseases in hop production, Vanden Heuvel says. Hops are susceptible to powdery mildew and downy mildew, as well as thrips and spider mites.

“It has to be treated as an edible, so the spray routines — the chemicals that [you] are allowed to use in the greenhouse — is greatly reduced,” he says. “They’re on a spray rotation similar to impatiens for impatiens downy mildew, so we’re spraying very regularly. But the chemical base to rotate through is not nearly as broad. That presents challenges in itself.”

Greg Stelzer, co-founder of finished hydroponic grower 24 Hour Hops, says another production consideration is that hops require vernalization to improve their plant vigor and root hardiness, and produce higher yields of better-quality cones than first-year plants.

24 Hour Hops has been growing hops in a 3,000-square-foot greenhouse leased from the University of Arizona since 2017, but recently halted production as it looks for investors.

To vernalize its hop plants, 24 Hour Hops chopped the crops down to the root crowns and placed those in refrigerators to simulate winter conditions.

“With that said, we did do some second grows,” Stelzer says. “We chopped them down and then just let them grow again to do some experimentation. They did pretty well. We just figured that since Mother Nature tried it, we’d try it both ways.”

24 Hour Hops, along with the few other finished greenhouse hop growers, often specialize in fresh hops. While most hops are dried right after picking, fresh or “wet” hops go straight into the beer-making process.

The operation carved out a niche selling its fresh hops to home brewers, but it also sold to some craft brewery clients such as SunUp in Phoenix and Dubina in Glendale, Arizona.

24 Hour Hops grew in Dutch buckets, trellising the climbing plant stems called bines. They leaned and lowered the bines, similarly to the way a grower of indeterminate tomatoes would treat vines in the same production system. They also used LEDs to manipulate the photoperiod and shade cloth to reduce the amount of brutal Arizona heat entering the greenhouse.

While Stelzer doesn’t come from a horticulture background (he worked in the tech sector) he says he would imagine experienced growers could catch on to producing hops pretty quickly.

“I think this is one of those plants that wants to grow,” he says.

Still, growers must consider the time it takes for hop plants to mature. Sandy Ridge aims to save its finished grower customers time by allowing them to get a full yield of hop cones a year sooner than if they grew from rhizomes, Vanden Heuvel says. The reduction is from three to four years, to two to three.

At the University of Florida’s Mid-Florida Research & Education Center in Apopka, Florida, Pearson and his colleagues have grown hops in a semi-enclosed greenhouse, then in a heated and cooled greenhouse with a polycarbonate roof, using deep water culture hydroponics.

“We ended up doing a post on social media showing a hop harvest in January,” Pearson says. “We got quite a few positive feedbacks from folks in the Pacific Northwest, thinking how cool it was that we had some fresh hops available. And I see that ... here we have fresh hops available when nobody else in the U.S. has that.”

Challenges of greenhouse hops production

Despite the potential for greenhouse growers to offer hops year-round, Pearson says many questions remain about growing hops in a greenhouse and its feasibility for profitable commercial production.

“There’s pros and cons to every production system. And yes, greenhouses have the con of oftentimes being more expensive than a field because you’re paying for electricity; you’re paying for water; you’re paying for light. But the pro of it is you can control your environment to a higher degree.”

Jaki Brophy is communications director at Hop Growers of America, a nonprofit trade organization based out of the high hop-producing city of Yakima, Washington. She says growing hops in a greenhouse usually involves expensive equipment designed specifically for them.

“We’re finding that some people are trying different things, like growing in greenhouses, but that would be quite expensive,” she says. “And then people are tending to just drop out of growing hops in different regions now because there’s a capacity that you have to hit to be financially feasible, because there’s a lot of things that people aren’t considering in their budgeting process.”

When it comes to cost, Brophy and Pearson both reference cost estimates. Although the estimates are for outdoor production, Pearson says greenhouse growers could adjust by inputting their own unique costs.

Demand for dwarf

Downy mildew can affect hop foliage near the ground, so Pearson recommends that greenhouse hop growers prune toward the bottom of their plants to prevent the disease. They can also select certain varieties like Chinook, which produces more cones near the top of the plant versus the bottom.

Pearson says he is interested in working with hop breeders to breed dwarf and day-neutral hop varieties that could possibly help with some of the height and light requirements. Stelzer is also interested in dwarf varieties since leaning and lowering bines is labor-intensive in 24 Hour Hops’ 10-foot-tall greenhouse.

“Most of that [dwarf variety breeding] has come out of the U.K., and there has been some breeding for dwarf hop varieties in the Pacific Northwest to reduce labor costs of having these big, 20-foot-tall bines and specialized equipment,” Pearson says. “With that said, I have yet to get my hands on dwarf varieties. Because if they are there — and then again, I’ve seen documentation of them — they’re very coveted, and not everyone wants to share their germplasm.”

Knowing the market

One of the biggest considerations for greenhouse hop production is evaluating and meeting demand of a market that is largely already being served by producers in Washington, Oregon and Idaho. In fact, 97% of the U.S.’s hops are grown in just those three states, according to the 2017 Census of Agriculture.

When produced outdoors in the Pacific Northwest, fresh hops are only available once a year in the fall. That’s because lupulin — a compound responsible for important beer qualities such as “bittering” aromas and tastes — is only available on cones flowering outdoors in the fall, Brophy says, and cannot be replicated in greenhouses at other times.

The environment is likely responsible for lupulin production, Pearson says, but he has not seen any research that states exactly how. He and his colleagues found in their greenhouse studies that lupulin levels increased in consecutive production years but had not reached the levels of those reported for similar varieties grown in the Pacific Northwest.

Hydroponic greenhouse grower Mark Koehler, owner of Hank’s Hops in Von Ormy, Texas, aims to produce fresh hops year-round, harvesting three times a year. After two years researching and developing hops production in his greenhouse, Koehler completed his first harvest for commercial sales in the spring. He notes that his hops’ lupulin levels are high, as are the alpha acids in the lupulin glands.

“The brewers are looking for high alpha acid levels in the hops because that enables them to use less of them, and they’ll have more aromas and more flavors,” Koehler says. “The varietal that I’m growing right now — they usually average between 7 and 9% alpha acids. The ones I grew were 11.13%.”

Koehler delivered Hank’s Hops to San Antonio’s Southerleigh Fine Food and Brewery, and the operation brewed them into an all-Texas-grown-ingredient beer to serve in its taproom.

“As far as I know, this beer that’s coming out with Southerleigh is the first all-Texas-ingredient beer to be sold commercially,” Koehler says. “That’s everything from the yeast to the malt, the hops — everything came from Texas.”

For many brewers, acquiring fresh hops to brew beers locally would be preferable to having pelletized hops or dried cones shipped in from afar, as long as orders can be fulfilled and the quality is controlled, says Charles Vallhonrat, executive director of the Texas Craft Brewers Guild.

“People love to make fresh-hop beers, but they’re difficult to make,” Vallhonrat says. “You’ve got to get the hops; timing has got to work out and you’ve got to ship it and everything.”

An Orlando, Florida, company called Florida Hops breeds hops, trials varieties, grows hop plugs in a greenhouse and consults with hop growers throughout Florida. Founder Richard M. Smith says Florida hop growers, most of whom are outdoors, are garnering interest from brewers.

“We have folks from Colorado who work in a brewery like, ‘Oh man, I love the fact that I can get wet and fresh hops in Florida. I thought I wouldn’t be able to do that,’” Smith says. “But then you have folks that say, ‘I’ve never used this before and I’m hesitant to change what I’m doing.’”

A few different factors influenced Smith’s decision to start working with growers through Florida Hops, which he founded in 2016: the locavore movement, the ability to support the brewing of fresh-hop beer and the opportunity to provide hops education to a state population that is already enthusiastic about beer.

“The potential for us is to produce something local to add to the whole craft beer climate,” Smith says. “Hop yards become an attractive piece to this whole thing, so there’s that interest in there. And there’s a lot of collaboration between the brewers and the growers. They’re able to attract people into the breweries because now we have a wet-hop beer.”

Since greenhouse growers can mature hops faster indoors than outdoors, some greenhouses are growing specific varieties to fill requests from their brewer customers, Vanden Heuvel says.

“If some of these small brewpubs want to have a harvest ale and serve it in the middle of February, they can go and get these wet, fresh-picked hops and serve their harvest ale in February and have it as a mainstay at their pub,” he says.

Pearson says the type of customer will largely determine if growing niche product in a greenhouse is feasible. It could make sense for a greenhouse to start plants for hobbyist growers and brewers, and agritourism operations to finish. Growing in a greenhouse as a commercial finished grower could be more complicated.

That’s not to say that it’s impossible. Koehler, for one, has answered other growers’ questions about his process, and thinks more greenhouses will start growing hops. He has a few words of advice.

“Be ready to work, but it’s a labor of love” Koehler says. “It’s fun and it’s a very fun industry to be a part of. When you get to have a drink of that beer that you grew, it’s a cool feeling.”