Supplemental lighting can be as unique as the crops a greenhouse owner grows. Greenhouse Management magazine spoke with Elizabeth Leider, assistant production manager of Leider Greenhouses in Buffalo Grove, Illinois, to get a glimpse into how one greenhouse operation tailors its lighting to achieve better production results.
Greenhouse Management: What crops do you grow and in what type of greenhouses?
Elizabeth Leider (EL): We are a wholesale flower grower. We grow spring and summer annuals, and we also grow a few perennials. Most of the annuals we grow are used for container gardening or as bedding plants. In the summer, we grow hardy mums and we grow poinsettias for the Christmas season. We also grow Easter lilies, hydrangeas, and a few indoor-blooming plants. Our facility was built in 1963 and we’ve expanded onto it multiple times, so we have glass greenhouses, double polycarbonate greenhouses and polyethylene greenhouses.
GM: What types of supplemental lighting do you use and on which crops?
EL: Originally, we only used HPS. I would say in the last eight years we’ve started investing in LED. The HPS lights are primarily still used for our indoor bloomers and for propagation. We use them to either extend the day length or just increase the amount of light in the greenhouses.
The LEDs we primarily use for propagation. We also use them to further speed up some of our crops. For instance, we noticed just this year that the zinnias we put under LED lights were about a week ahead of those that weren’t.
The LED lights are newer toplighting. I believe the color spectrum is a red spectrum, but they’ve really improved it recently, so it’s not as harsh on your eyes. It’s got a white quality to it. So, we have some older lights and we have some newer ones as well. Our older lights are definitely pinker, harsher, and the newer ones are a lot easier to work under.
GM: Do you have different lighting setups based on the type of greenhouse?
EL: In general, glass lets in more UV light, whereas the polycarbonate filters it out a little bit more. We don’t have any LEDs in our glass houses. Those are very traditional-style houses, and we just use them for specific crops. Easter lilies, for example, really like the glass houses and won’t get enough light if you put them in a polycarbonate house.
Our propagation houses are, I believe, double polycarbonate. All of our greenhouses were built to grow indoor-blooming plants. They weren’t built to grow annuals, so we really need the supplemental light to help the annuals beef up.
GM: Can you talk more about why you use supplemental lighting and how important it is to the success of your crops?
EL: In regard to propagation, it definitely increases the rooting speed for a lot of the unrooted cuttings that we propagate for most crops. And supplemental lighting in general, it’s a more uniform distribution of light because some of our houses are kind of old and they’re not very tall. There are certain places that get shadows. In the past, that shadow would really impact the uniformity of the crop. Especially when we’re just beginning to propagate. Being able to have a toplighting makes the lighting way more uniform.
We also need supplemental lights for certain crops because of short days. We’re in Chicago, so there can be periods of time when we have very low light that goes on for a week on end.
GM: Are you planning to expand your supplemental lighting?
EL: We’re probably going to put more lights in some of our outside poly houses that we tend to grow cold crops in. We grow some early spring crops that are grown cold, but they like high light. This last year we did an anemone trial and anemones really like a lot of high light, so they did really well grown cold in these poly houses with the supplemental light. We did full LED and HPS light for those.
We’re also trying to transform some existing space that we used to cool bulbs. We don’t grow nearly as many bulbs as we once did, so we have a lot of cooler spaces essentially sitting empty. I’m working on a project to convert that vertical space into an LED-lit vertical operative type system.