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.
Trickster Golden Bronze
Photo courtesy of Karl Batschke
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.
Zuma Orange
Photo courtesy of Karl Batschke
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.”
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.
Kyle, left, and Greg Stelzer of 24 Hour Hops
Photo courtesy of Greg Stelzer
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.”
24 Hour Hops picked its fresh hops on a given morning and shipped them out the same afternoon.
Photo courtesy of Greg Stelzer
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.
The University of Florida has linked up with Florida breweries First Magnitude and Redlight Redlight for special beer releases. “They’ve been just wildly successful in terms of interest,” Pearson says.
Photo courtesy of Brian J. Pearson
“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.”
“I’ve had a few different growers visit my greenhouse. I'm completely okay with sharing what knowledge I have, as long as they’re not in my town competing against me,” says Mark Koehler of Hank’s Hops.
Photo courtesy of Mark Koehler
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.
One of Florida Hops’ clients in Florida that it consulted with
Photo courtesy of Richard M. Smith
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.
Richard M. Smith of Florida Hops
Photo courtesy of Richard M. Smith
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.”
The variety of hops a grower chooses makes a big difference for the brewer since each variety imparts a different flavor and a different amount of bittering for the beer.
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.
Mark Koehler, right, of Hank's Hops
Photo courtesy of mark koehler
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.
Brian J. Pearson of the University of Florida has been growing hops for seven years. A home brewer, he began growing them in part because he was not impressed with the quality of the hops that he received.
Photos courtesy of Brian J. Pearson
“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.”
Head-turning varieties at Spring Trials
Features - Events
At the 2019 California Spring Trials, breeders showcased their latest in petunias, begonias and more.
At the 2019 California Spring Trials, Greenhouse Management saw everything from a rainbow of petunias and calibrachoas at numerous stops to unique fall and winter crop alternatives to nearly 6-foot-tall salvias.
Breeders and distributors offered new and trendy ideas as well as their takes on existing trends. In begonias, large sizes for the landscape and trailing habits for pots and baskets are gaining steam. In perennials, silvery foliage appears to be currying favor with consumers.
Below, we have compiled a photo gallery of some of the standout plants in several categories.
Begonias
Benary introduced four new colors in its Funky series of trailing, basket-type, heat-tolerant begonia hybrids that perform well in mixed containers and grow in partial to full sun. Funky has high germination rates and is easy to ship. The new colors for 2020 are Light Pink, Orange, Scarlet and White. The Tophat interspecific begonia series from Syngenta Flowers finishes one week earlier than others in its class and is bred to finish in 306 packs up to large patio containers. New for 2020 is Bicolor which, like others in the series, features large blooms that sit atop of the foliage. With a mix of foliage and flower colors, Sakata Seed America’s Viking and Viking XL series of hybrid begonia thrive in the landscape or containers. Viking is available in eight colors and Viking XL is available in four colors, including the All-America Selections-winning Red on Chocolate.
Petunias
Wave Petunias from PanAmerican Seed will celebrate 25 years in 2020. Classic Wave Purple — an All-America Selections winner — was the first color to be introduced in the well-known series. To mark the anniversary, PanAmerican will be producing point-of-purchase materials for retailers. Easy Wave Lavender Sky Blue is new for 2020 and, just like Classic Wave Purple, it is low-growing and wide-spreading. Danziger showcased several petunias including a new color to its Amore series. Amore King of Hearts (pictured) is compact and early to flower. It works best in combos, quarts and baskets. Danziger also featured new pots for the Amore line and ideas for Mother’s Day marketing. New to the Capella petunia series are Baby Pink, Ruby Red and Neon Pink. Lisa Heredia, marketing and key account manager at Danziger, says Capella petunias require little to no PGRs and are great for pot-tight production. New Cascadias Purple Ice petunia features a semi-trailing habit with strong, long-lasting flowers.
Perennials
American Pie ‘Cherry Pie’ dianthus from Pinks by Whetman will follow in the footsteps of the top-selling ‘Georgia Peach Pie’ for the 2020 season. Robert Bett of PlantHaven says he’s quite impressed with its foliage color and prolific bud set. As a bonus, the cherry-red flowers on strong stems work great as a cut flower for the consumer.Echibeckia Summerina Blazing Fire was one of the star plants at Pacific Plug & Liner, planted in containers near the entrance of their Spring Trials display with its own vignette. Echibeckia is fast-growing, good for shoulder season sales, can be grown in multiple pot sizes and is heat tolerant. One 72-cell liner can easily fill larger pots such as 1.5 gallons and deco pots.
Foliage
Green Fuse Botanicals introduced a new Begonia Rex series for 2020 called Bewitched in three colors: White, Wintergreen and Red Black. Steve Jones, president, emphasized that the plants can be used indoors or out, noting the robust popularity of houseplants. As part of its First Look pre-introduction program, the company also provided a sneak peek for what 2021 will have in store — three more colors in the Bewitched series: Cherry, Pink and Rose. A greenhouse crew may ask, “Which way is up?” when planting caladiums. Classic Caladiums, which are now available through a new partnership with Proven Winners, helped solve this dilemma by painting the eyes of the tubers so there’s no question that the painted side faces up. New to the Proven Winners line is the Heart to Heart Series including ‘Caribbean Coral’, ‘Heart and Soul’ and ‘Lemon Blush’. J Berry Nursery’s Crown Jewel Begonias currently offer four selections in the series: Positively Peridot (pictured), Enduring Onyx, Tenacious Topaz and Joyful Jasper. Marketing and Brand Manager Tamara Risken says the nursery is working on oranges and reds to add to the collection. Thick leaves help the Crown Jewel Begonias withstand higher temperatures and the foliage color gets darker with cooler temperatures.
Foliage
Heuchera LITTLE CUTIES ‘Shimmer’ from Terra Nova Nurseries is constantly blooming and has multiple crowns. This coral bells, hardy to USDA Zones 4-9, is able to fill pots quickly, but won’t overpower in a mix, says Sales Manager Larry Finley. The pink, fragrant flowers of ‘Pink Diamonds’ Dicentra from Walters Gardens will flower all season long. This bleeding heart attracts bees and hummingbirds, and is deer-resistant. Growing to 12 to 16 inches high with a 16- to 18-inch spread, it is easy to produce in a container and to get to flower.Skyscraper Senecio Senecio ficoides ‘Mount Everest’ from Sunset Western Garden Collection can add a dramatic, vertical element to mixed succulent containers. Skyscraper is an upright grower, reaching upwards of 5 feet tall. In colder climates, Skyscraper can be grown indoors as a houseplant. It will be available for retailers this year.
Other Standouts
For 2020, Dümmen Orange is introducing Fleur de Rock, a new collection of alpine garden plants consisting of an iberis, two delosperma, an aubretia and a saxifraga. Consumers want crops that are easy to plant in the garden with low-water and low-maintenance requirements — and this collection fits the bill.Preciosa Zinnia (Zinnia elegans) from Takii Seed is a new series that is early flowering. It produces large, double, dahlia-like blooms and is being launched in eight colors, including a mix. Colors include Light Yellow, Pink, Rose, Scarlet and Tropical Blend (pictured here). Plants grow to 10-12 inches tall with a 4-inch bloom. Preciosa also has heavier branching, uniformity in production and doesn’t need a pinch. Benary has launched the Taka Tuka Bidens ferulifolia series with four new colors: Red Glow, Red Yellow Center, Orange Yellow Center and White Yellow Center. The breeder pulled the series name from the tales of Pippi Longstocking.
Trickle systems are a good choice for spaced potted plants.
Photos and graphic courtesy of John W. Bartok, Jr.
Making your irrigation system more efficient can save energy, labor and water. The savings will help to pay for the improvements. The following are a few areas that should be considered.
Select the best system for the crop. Overhead sprinkler systems work well on crops that are grown on the floor such as annuals and perennials in flats. They waste a lot of water when used on container crops as up to 75% of the water never gets to the root zone. For these crops, drip, trickle flood and trough systems are a better choice. These save 50% or water and require smaller piping and lower pump pressure.
Design the system for uniformity of application to reduce the total water needed. Over-irrigating some plants so that the driest plants have adequate water is wasteful of both water and energy.
Size the system for the water supply capacity. Compare the peak use against the supply. Use zoning and an irrigation controller to spread the supply over a longer time period. An alternate is to install an intermediate storage tank that will make up the difference.
Size the pipes to reduce friction loss. Water flow is affected by pressure, length and number of fittings. The generally recommended flow rates for 100’ of plastic pipe are shown in Table 1. For longer runs, the flow rate decreases. Most systems have a pressure tank that provides water at between 30 to 50, or 40 to 60, pounds per square inch (psi). Lower pressure reduces flow and higher pressure increases energy use and may damage the plants. Valves and fittings should generally be the same size as the pipe.
Manage the system. Track water use by evapotranspiration rate. There are many sensors that have been developed for measuring the moisture content of the soil. Soil moisture tension is used in conjunction with evapotranspiration estimates to determine how strongly water is held in the soil.
A common system now available to manage irrigation is vapor pressure deficit (VPD). It is a measure of the difference in the humidity inside the leaf and the humidity of the greenhouse air. The computer calculates the amount of moisture lost by the plants and activates the irrigation system to make up this difference.
A zone controller can save considerable water and time as compared to manual control. This frees up the manager for other tasks.
Install a boom system to get very uniform coverage on plants grown in pot to pot, plug trays and flats.
Maintenance can reduce energy use and prevent problems. Select pumps with premium efficiency motors. This can save up to 10% in electricity use. Check voltage at the pump as low voltage will overheat wiring and add to the electricity use. Variable speed drive pump motors have been used but are best for systems with multi zones of different sizes.
Install filters with the correct mesh for the nozzles and check frequently to see if they are clean. Self-cleaning filters can save time and energy. Multiple filters with different mesh may be needed if the water has many particulates.
Check the system frequently for plugged nozzles or drippers. These should be replaced to get even flow to all the plants. Leaks in the pipes also increase water use and should be repaired. A leak of 60 drops per minute will waste 113 gallons per month.
An efficient irrigation system will save water and labor. If properly designed and maintained, it can meet the plant needs without waste.
John is an agricultural engineer, an emeritus extension professor at the University of Connecticut and a regular contributor to Greenhouse Management. He is an author, consultant and certified technical service provider doing greenhouse energy audits for USDA grant programs in New England. jbartok@rcn.com
Calcium conundrums
Departments - Production Pointers
Calcium deficiencies can cause plant health issues, but growers can take practical steps to prevent any issues.
Calcium deficiencies can lead to disorders such as blossom end rot on tomatoes and peppers, leaf tip burn on lettuce, and bract edge burn on poinsettia. While calcium deficiencies may occur when insufficient calcium is available to plants, it can also occur when the greenhouse environment is unfavorable for uptake or from antagonisms with nutrients that compete for uptake.
Photo courtesy of Christopher J. Currey
Calcium (elemental symbol Ca) is, along with magnesium (Mg) and sulfur (S), one of three essential secondary macronutrients. While all 12 essential macro- and micronutrients are required for a plant to successfully complete its life cycle, calcium and its deficiency symptoms reduce the marketability of horticultural products. In poinsettia, a calcium deficiency results in necrotic bract margins, referred to as bract edge burn. In lettuce, the margins of leaves, especially those at the center of a lettuce head, become necrotic; this is referred to as tip burn. Additionally, blossom end rot manifests when tomato and pepper fruits deficient in calcium develop necrotic spots at the bottom of fruits where the whorl of petals or corolla once was. While a simple remedy to any calcium deficiency may be to simply provide additional calcium, this may not always prove to be the remedy you need for solving calcium deficiencies.
Calcium deficiency symptoms may develop if insufficient calcium is provided to plants through fertilizers. However, there are a number of other factors that may result in calcium deficiencies. First, calcium may be present in the substrate for container-grown plants or in the nutrient solution provided to hydroponic plants, yet it may not be taken up by plants. Calcium is not taken up rapidly by plants through active uptake, where energy is expended to absorb the nutrient. Rather, calcium is primarily taken up through bulk flow, when water is being taken up, meaning calcium uptake is very closely linked with transpiration. When plants are actively transpiring, calcium uptake is promoted. Alternatively, when transpiration is diminished or inhibited, calcium uptake declines. That is why, even when there is sufficient calcium available for plants for uptake, calcium deficiencies can appear if environmental conditions are not promoting calcium uptake. For example, calcium deficiencies can occur when light intensity is low or relative humidity is high. Altering the greenhouse environment by providing additional light with supplemental lighting, reducing humidity by increasing venting and dehumidification, or promoting additional airflow can promote transpiration — thereby enhancing calcium uptake and tissue concentrations.
In addition to promoting transpiration and, thereby, calcium uptake, calcium also interacts with other nutrients that may inhibit its uptake. For example, magnesium can compete with calcium for uptake. Magnesium is a divalent cation like calcium, meaning they have a positive charge of “+2” (i.e Mg2+ and Ca2+). As a result of their similar chemical structure, these two elements have an antagonistic relationship, whereby an abundance of one may inhibit the uptake of another. If calcium levels are too high, magnesium uptake can be suppressed; similarly, excessive magnesium can inhibit calcium uptake. When evaluating plant nutrition programs, you want to maintain approximately three to five parts per million (ppm) calcium for every ppm of magnesium. But this is not just a matter of evaluating fertilizers alone.
In addition to fertilizers, you’ll also want to look at things like your substrate and water sources. When substrates are amended with limestone to increase the pH, as is commonly the case for sphagnum moss-based substrates, there will be additional magnesium as a result of the dolomite [CaMg(CO3)2] content in the limestone. If possible, use calcitic limestone in lieu of dolomitic limestone, which lacks magnesium. Also, if your water source is high in alkalinity, you’ll also want to measure the hardness, or the calcium and magnesium concentration. If you have high alkalinity, you may need to look at adding additional calcium to get closer to the ideal Ca to Mg ratio.
Calcium deficiencies can result in symptoms that make both food and flower crops unmarketable. While calcium deficiencies may result from inadequate supplies of calcium to plants, the greenhouse environment and other nutrients may suppress calcium uptake. Evaluate the environmental conditions and cultural practices to try and identify what may be causing calcium deficiencies and what you can do to fix them.
Christopher is an assistant professor of horticulture in the Department of Horticulture at Iowa State University. ccurrey@iastate.edu
John W. Bartok Jr.
Christopher J. Currey
