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It's heating up out there, and regardless of normal rainfall levels over the past year in drought-stricken states such as Texas and California, water restrictions and conservation efforts won’t be dialing back anytime soon — if ever. As a grower, this means you have no choice but to continue to make adaptations in your business and product selection to weather the weather, so to speak, as well as partner with other industry sectors to control consumer messaging.

In areas where water restrictions have been most tight, many homeowners were scared out of finding new ways to maintain a green landscape and have let their outdoor spaces go. Brown lawns and dead foundation plantings are more common sights these days. However, not all property owners are abiding 100 percent by local water restrictions. I continue to see neighbors of mine in Dallas, Texas running their irrigation systems frequently, and wastefully, outside of water restriction guidelines. Some of the biggest culprits are large properties tucked behind tall privacy hedges; they often run irrigation systems daily. Restrictions be damned. There just aren’t enough code enforcement agents to write tickets and discourage violations, or cities willing to grapple with wealthy property owners. As such, some businesses in areas with water restrictions may not yet feel the full effect of them kicking in.

On that point, irrigation practices amongst growers may not be evolving as quickly as needed either, due to existing irrigation infrastructure or an unwillingness to change processes. Eventually, things will get to a point where none of us can run from the restrictions, or the real need for serious water conservation efforts.

As water-needy lawns continue to shrink, there is space in the market for you to fill that real estate with water-wise perennials, shrubs, and trees. If you’re a grower that has always specialized in drought-tolerant or Mediterranean climate plants, you’ve no doubt worked to make the most of the current water situation and it’s potentially helped your business. However, other growers will tell you that while they may be increasing the quantity of water-wise and succulent plant material in their mix, sales of these products don’t yet make up for losses in sales of more traditional annuals and perennials. Not only that, but some lost customers are simply lost for good.

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The water crisis has forced some innovations in automated irrigation control in growing operations, as well as adjustments and improvements to soil mixes to help conserve water. For example, some growers are finding earthworm castings to be a beneficial media amendment for both water conservation and reducing fertilizer inputs. Soilless growing, as a means to better control and conserve water, continues to grow in popularity. But we still have a long way to go.

Plus, I’m still not seeing big investments in water-conserving technology by residential consumers. There are ways to water smart and within water restrictions, but your irrigation system needs to be up to the task. I put my money where my mouth is and renovated my entire home landscape irrigation system to drip and high-efficiency rotary heads where necessary, all controlled with a smart controller and remote app control access.

That said, my clients in the landscape industry continue to bemoan the reality that most residential and commercial property owners still won’t part with the cash necessary to upgrade their systems to use less water, or renovate their existing plant material to more water-wise specimens. This is true even though doing so means they could keep a lusher landscape that also uses less water. I suspect property owners won’t make the big shift until they’re mandated to do so — same for some growers.

In 2016, Texas created the Lawn & Garden Water Smart Tax Holiday during Memorial Day weekend, to encourage consumers to go water-wise in their landscapes. During the tax holiday, shoppers can purchase certain water-saving products tax free. Any product with a WaterSense label or logo is on the list for both personal and business use. Additional water-conserving products without a WaterSense label that are used or planted for conserving or retaining groundwater, recharging water tables, or decreasing ambient air temperature, can also be purchased tax free for residential use. If you have a program such as this in your state, you should help promote it.

The Texas Nursery and Landscape Association has also developed a new Texas Water Smart Certification, which can be obtained by current TNLA certification holders, to help consumers identify professionals who can help them specifically with water conservation needs in their landscape. I talk about this certification and how businesses can market the importance of water conservation in this video: bit.ly/2uRDYUQ

Be sure to check with your state’s industry organizations to take advantage of similar professional development and marketing opportunities.

As green industry businesses, we must work more assertively to educate the end consumer about strategies they can and should employ to keep their landscapes beautiful and healthy, while managing their water wisely. The future of our industry depends on it. While you might not be used to getting involved with retail- and landscape-related marketing campaigns, customers of these industry segments are ultimately your end customer. Supporting your industry customers with group-effort marketing campaigns that help landscapers and homeowners navigate water restrictions is in your company’s best interest.

Leslie (CPH) owns Halleck Horticultural, LLC, through which she provides horticultural consulting, business and marketing strategy, product development and branding, and content creation for green industry companies. lesliehalleck.com

In my travels to greenhouse operations, I notice the employment of greater numbers of physically challenged workers. This trend stems from several factors:

1. ADA. Today, there are about 54 million Americans with physical or mental disabilities. The Americans with Disabilities Act (ADA) that went into effect in 1992 requires that all businesses with 15 or more employees follow the guidelines of the ADA. These include:
• Job descriptions that list the essential functions or tasks to be performed, not the method of doing them.
• Interviews and tests that don’t discriminate against those with disabilities.
• Accessible accommodations and workplaces.
• Job restructuring and part-time or modified work schedules.
2. Training programs. There are more programs that train people with disabilities so that they can be gainfully employed. In New England, for example, there are more than 50 schools, hospitals, prisons and rehabilitation programs that have greenhouses for training and skills building. Some programs develop a worker’s skills and then find employment for that individual. Others use a team approach and can provide you with a group of workers and a supervisor to work in your greenhouse each day. Many individuals with disabilities make excellent employees.
3. More seniors. We are also seeing more senior citizens employed. As the population becomes older, there are more senior citizens, many with disabilities. Many seniors come from early retirement programs or company buyouts and they may have specialized skills that can benefit a greenhouse operation.

Providing for the physically challenged

To prevent discrimination against these workers, ADA requires that you make reasonable accommodations to employ the disabled. ADA defines reasonable accommodations to include making existing and new facilities used by employees readily accessible to and usable by individuals with disabilities.

When building new facilities, it is fairly easy to include provisions for handicapped accessibility without adding much to the cost of the building.

In existing greenhouses, it is more difficult and expensive. ADA does not require changes if it imposes an undue hardship on the business. This is defined as “an action requiring significant difficulty or expense that is costly, extreme, substantial, disruptive or that fundamentally alters the nature of the business.”

Common sense is probably the best approach. Frequently, modifications to parking, access and work stations are all that is needed to accommodate a person with a physical disability. This could mean designating a handicapped parking space near the entrance, replacing steps with a ramp, widening a door or adjusting the height of a work table.

Retail restrictions

Retail greenhouses are subject to greater restrictions than production facilities and have to be fully accessible. For example, in a retail greenhouse, the main aisle has to be at least 48 inches wide, whereas a production greenhouse can get by with a 32-inch-wide main aisle.

Making retail facilities readily accessible makes shopping easier for the disabled and elderly, and can increase business.

Watch for physical barriers

These are a few of the physical barriers to watch for when you are in the process of new construction or renovation:

• Curb cuts between sidewalk and parking lot. These are easy to install when putting in new sidewalks. Asphalt patches can be used to provide gradual ramps in existing areas.
• Ramps having a maximum slope of 1 foot in 12 feet allow easy access for both walking and wheelchairs. The length should not exceed 30 feet between level platforms. A platform should be provided at the top, bottom and where a change of direction occurs. The surface should be non-slip. Handrails should be 32 inches high.
• A level platform is needed in front of each door. It should protrude 5 feet from the door and be 1 foot wider than the door opening on each side. Thresholds less than ½ inch high make access easier. A universal access symbol should be posted nearby.
• Parking spaces designated with a handicapped emblem should be 13 feet wide to permit room at the side of a car for wheelchair access.
• Restroom facilities should be easily accessible. This includes a stall size of at least 60 inches square to accommodate a wheelchair, grab bars to aid in moving around, a lavatory counter top height of 34 inches or less and a knee clearance of 29 inches to allow wheelchair access, and water faucets with levers or separate fittings to aid those with hand limitations.
• Electrical switches, thermostats and automatic door openers. Optimal control height is 40 inches.

For greatest efficiency, the work area must be convenient and free of obstructions. An adjustable table height may be needed for individual workers. Containers, seedlings, growing media and other materials should be located as close to workers as possible. Signs with large lettering, special hand tools, vehicles with hand controls and back or wrist supports may be required. Video training may be better than printed training manuals.

The cost of accommodating people with disabilities is much lower than you might expect. In addition, tax credits may be available for barrier removal or for special equipment.

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

Algae can cause several problems for greenhouse growers. First, algae on the substrate surface can form a “crust," making it more challenging to evenly rewet substrate during irrigations. Additionally, algae can diminish the marketability of your crops because plants with algae covering the substrate surface can be less appealing to consumers. Finally, algae on greenhouse floors can be hazardous to employees, creating a slick surface that could cause someone to lose their footing. This month’s Production Pointers aims to help you understand algae and how to manage it in your greenhouse.

Where do algae come from? Algae have multiple modes of reproductive, including both sexual and asexual methods. Regardless of how they reproduce, algae must have a source from which it propagates. And there are several sources in and around the greenhouse. Algae populations that are already established in the greenhouse are the most common sources of propagules. Common locations for algae are places where water frequently puddles such as underneath benches, in walkways and underneath gutters. Algae also grows on equipment such as mist nozzles (Fig. 1), benches (especially wooden ones), and leaky hoses or spigots that frequently stay wet for extended periods of time. There is no single “silver bullet” that can completely eliminate algae. But there are several steps that, if taken together, can reduce algae in your facility.

The first key step to reducing algae growth is to put together (and stick to!) a plan for improving greenhouse sanitation. You must reduce algae elsewhere in your propagation house since any algae present in a greenhouse can act as a source for additional algae populations to establish and grow. The first place to check for algae are those areas mentioned earlier: anywhere that water may pool or surfaces that may stay wet. Also, check the tools and equipment that are used during propagation. It is good practice to routinely use a water nozzle with good pressure, or preferably, a power washer to clean locations and equipment where algae are growing.

Once these areas and equipment are clean, you can use an algaecide such as a hydrogen dioxide and peroxyacetic acid product (ZeroTol 2.0 or OxiDate 2.0, BioSafe Systems) or a quaternary ammonium product (Physan 20, Maril Products; Green-Shield, Whitmire Micro-Gen) to kill any remaining algae (Fig. 2). There are different application methods for these products, so be sure closely follow the label instructions. Be mindful of any plant material in the greenhouse that may come into contact with some of these chemical treatments. Phytotoxicity can be a problem, and one you’d rather avoid. If you are trying to control algae on the surface of substrate plants that are growing in, you need to be mindful of which algaecide you apply. Although many algaecides are not labeled for application to plant material, Physan 20 (a quaternatry ammonium product) is labeled for this use. Physan 20 can be applied as a substrate drench or can be sprayed on the substrate surface. As previously mentioned, be sure to always follow label directions.

There is no single “silver bullet” that can completely eliminate algae. But there are several steps that, if taken together, can reduce algae in your facility.

Seeing algae throughout your greenhouse can be discouraging, as it poses a safety hazard and creates a less-sanitary environment. If allowed to grow in your facility unchecked, algae can cause problems for your employees and crops. Although there isn’t a silver bullet that can reduce or eliminate algae, careful sanitation of the greenhouse and equipment, modifying the environment and cultural practices, and chemical control are all tools that can be used to help combat algae.

Christopher is an assistant professor of horticulture in the Department of Horticulture at Iowa State University. ccurrey@iastate.edu

Ventilation, evaporative cooling and shade curtains: These are some of the most common cooling methods in the greenhouse, and ranked in importance by Dr. Nadia Sabeh, founder and president of Dr. Greenhouse (doctorgreenhouse.com), and a mechanical and agricultural engineer.

Here, we will focus on evaporative cooling, which Sabeh says is her “specific area of expertise.”

What is evaporative cooling?

Evaporative cooling helps control temperature and humidity, Sabeh says. By themselves, fans draw heat out of the greenhouse that collects as a byproduct of solar radiation, but draw moisture out as well. Evaporative cooling works to add moisture back into the greenhouse.

Comparable to how humans sweat — water from a person’s skin evaporates and carries heat away from the skin — evaporative cooling uses water to capture heat from the air, causing the air temperature to reduce and the moisture content to increase, Sabeh says. The process involves the transfer of sensible (observable) heat to latent (hidden) heat. “We’ve moved sensible heat into hidden [latent] heat, which is trapped in that water vapor,” she says. “Now we have cool air that has also been humidified — because we’ve evaporated water — moving through the greenhouse.”

Evaporative cooling works best in climates where the air is hot and dry — places like Arizona, Colorado and California — rather than humid ones, and where growers need a combination of cooling and humidification, Sabeh says.

Ventilation generally works better than evaporative cooling in more humid locales, such as Florida, Hawaii and the Midwest. However, evaporative cooling in such areas can help growers achieve a slight temperature reduction, which can be beneficial if they are willing to invest in a system that cannot provide all the cooling required all of the time.

Pad and fan systems

Pad and fan systems are the most common evaporative cooling method, Sabeh says. In this type of system, a wet wall is placed at one end of the greenhouse and fans are installed at the other end. The fans pull air from the outside and across the wet pad, evaporating the water and cooling the air before it enters the greenhouse.

A major advantage of a pad, or wet wall, is that all of the water that is used for evaporative cooling is evaporated, Sabeh says. “You never have any water moving into the greenhouse that could get on your plants,” she says. “That’s a major advantage, especially over something like a high-pressure fog system, where we’re literally injecting water into the greenhouse.”

Pad and fan systems are simple to operate and control, Sabeh says. A pump runs water up through a pipe to a gutter above the pad, trickles water down the pad and drains it back into a tank, which the pump picks back up and recirculates. Meanwhile, fans are managed to a specific airflow volume based on temperature needs.

Water pumps and fans are going to require the most energy consumption, but the operating cost is still low, Sabeh says. “Relatively speaking, the cost of the material and equipment, and installation, is relatively low, and also the operating costs are really low, because again, you just have that little pump that’s circulating water onto the pad, and you have fans that operate as needed,” she says.

People also often have a sense of security when working with pad and fan systems because they have installed and used them before, Sabeh says. “It’s just tried-and-true technology,” she says.

One downside to pad and fan systems is that the pad, which is usually cellulose, often gets “neglected,” Sabeh says. “Two things can happen: one, algae can build up on the pad or in the water tank, and the other thing is calcium salts can build up on the pad,” she says. “Calcium salt builds up because there’s calcium in the water and when the water evaporates through evaporative cooling, it deposits calcium salts on the wet pad.” This scenario is especially true in areas with hard water.

To prevent algae colonization, growers and greenhouse managers can place a detergent tablet in their water tank, Sabeh says. And once calcium salts gather, some people use high-pressure sprayers to remove them, while others use solvents to dissolve them, Sabeh says. However, she says these methods can be difficult considering the “stubborn” nature of the salts — which are essentially barnacles — so she recommends greenhouse managers buy new pads if they can afford them. Putting water softener on the inlet to the water tank can also help limit the amount of calcium salts entering the system.

High-pressure fog systems

Another drawback of using pads and fans is that growers often experience a temperature and humidity gradient between the two ends of the greenhouse, Sabeh says. Commonly, temperatures rise from the wet pad to the fans, and by a differential of anywhere from 3 to 5 degrees Fahrenheit, depending on the run of the greenhouse.

Growers can largely avoid this issue by using a high-pressure fog system, where nozzles are distributed throughout the greenhouse and inject small water droplets (5-20 micrometers); the air inside the greenhouse then evaporates the water, Sabeh says. “The benefit of that is that you get a little bit more uniform environment — at least have the potential for a little bit more uniform conditions,” she says.

“I really recommend a high-pressure fog system as opposed to low-pressure mist,” Sabeh says. “Basically, what you’re doing is you’re injecting fine droplets of water into the air, usually over the plants. And so now you’re using ventilation fans to bring air into the greenhouse, or maybe you just are using natural ventilation with sidewalls and roof vents, and that moisture — those water droplets — gets injected into the greenhouse [everywhere] and then evaporates, creating a drop in temperature over the tops of the plants.”

Sabeh has worked on multiple research projects with high-pressure fog and low-pressure mist systems. One difficulty with these systems, she says, is to find the best way to evaporate water quickly enough so that it doesn’t land on the plants, but not so quickly that it doesn’t cool the air around the plants. “The problem with high-pressure fog and low-pressure mist systems is just trying to figure out how to balance water injection and ventilation rates,” she says. As a rule of thumb, Sabeh recommends placing nozzles no less than three feet above the top of plants to prevent water from getting on them.

Whether growers decide to use a pad and fan system or high-pressure fog system, evaporative cooling can help control temperature and humidity in the greenhouse.