Room for improvement

Greenhouse Management: What points do you take into consideration when evaluating whether to repair/retrofit or replace a greenhouse for a client?

Sylvia Courtney: One is the condition of the greenhouse frame if they’re using evaporative pad systems. Because often in steel structures… that area stays wet all the time, even with hot dip or with galvanized steel. It depends on how bad the water is, but I’ve seen places that, in as little as five years the frame of the greenhouse has been eaten away because of there being so much water.

Photo: Cassie Neiden

For the investment, we want to look at energy conservation. So I personally don’t ever want to build a greenhouse that doesn’t have a curtain system because it’s such a tool, but they are costly. From a commercial point of view, sometimes what happens here is that the glazing someone selects can help them get to a budget. So ideally, we want to have a long-term glazing, which is like polycarbonate or acrylic or glass. Polyethylene is significantly less expensive [but] does have a shorter term life.

Another thing to look at would be the sophistication of the control system, how there’s a range in the control and how sophisticated those need to be. That can have an impact on the cost of the project.

Where I own my home in Texas, people are more challenged with cooling the greenhouse. So an investment in something that can help them more effectively deal with the hotter months of the year, and be able to have another turn or grow 12 months out of the year and have revenue from that square footage, it’s a better investment. They’re less challenged. As we move north, it’s the opposite. That investment is in an effective heating system.

What [growers] have to do is evaluate how they can make selections on equipment that they can get the highest return on their investments.

Photo: Cassie Neiden

GM: What’s the typical lifespan of a greenhouse? What factors can affect this lifespan?

SC: Thirty to 40 years. Regularly scheduled preventative maintenance is key. Technology will have changed in that period of time, but equipment and control systems can be replaced with newer technology provided that the greenhouse structure is sound.

GM: If a grower has decided to replace or build a new greenhouse, how far in advance should they contact a design/build or structures company?

SC: The sooner the better. When you’re in a hurry, sometimes things fall through the cracks. Or if people try to manufacture it in a hurry, maybe they don’t have the time to do the process that they normally would.

Allow for time for the unknown things that might come up during the design process. Projects that require building permits usually have longer design time because of the time required for plan reviews and approvals.

On an institutional project, that time frame can be three to six months depending on the size and the complexity of the project because you’re having to factor in all the utility, all the site work, all those designs. So right now, we’re working on a project where the greenhouse is a very minor part of a new building on a university. So the building design part has been going on for two years now, but the greenhouse part hasn’t taken two years, although we keep starting and stopping.

From a commercial perspective, it’s a matter of months.

If you don’t have much equipment it’s going to take less time because there are fewer [elements] for you to design.

Photo: Karen E. Varga

GM: Do you have any advice when it comes to choosing suitable land for a greenhouse structure? (Infrastructure, neighboring lands, etc.)

SC: In my opinion, the first thing that should be done is to test the water that is available at the site to determine if it is suitable for growing plants. Because if you’ve got bad water, then you’ve got other costs associated with treating the water to make it useable.

[Another question to ask is] Are there enough natural resources available to support irrigating? Unless you’re going to use low-volume irrigation, can you get the volume of water that you need to run your operation whether you’re getting it from a city main or whether you’re drilling a well…are there sufficient resources available?

Secondly, are there any adjacent buildings or trees that would cast shadows on the site where the greenhouse would be located? Is there light pollution from other businesses or recreational areas nearby? Will the greenhouse create light pollution that would impact adjacent properties? One thing we see happening a lot right now is urban greenhouses for food production. So light pollution from other adjacent properties is a consideration.

Relatively level sites are more desirable than sites that would require either excavating or infill to level the site.

Another point to consider is traffic flow into and out of the site. We’ve seen facilities that were going to be on a main road [and had to consider] how is that going to impact the traffic? Or would the traffic on this main road be problematic for them to enter and leave either raw materials being delivered to them, or trying to get their trucks out to deliver to their customers?

Photo: Cassie Neiden

GM: It can be tempting to want the world when rebuilding or constructing a new greenhouse. What advice do you have for a grower who wants the moon, but has the funding to get much less?

SC: It is important to identify the items that provide the grower with the best tools to accomplish their goals. [For instance], curtain systems are a very valuable tool and it usually costs less for labor to install the curtain system when the greenhouses are being built than adding them later, when the crew installing the curtains would have to work over plants and around other equipment that might be in the way. It would be better to install the curtain system during construction of the greenhouse.

When considering use of supplemental lighting, be sure to design your electrical service to handle the load for lights that would be installed in the future.

When considering an Environmental Control System, give some thought to any equipment you might want to control in the future, so that the design on the initial control system would allow for control of equipment that you might add later.

It is also important to consider the “tools” that result in labor savings. [For example], automated irrigation systems can often pay for themselves in the first year of use, freeing up the workers to perform other tasks.