What’s With The Pink?

By Jim Pantaleo

Back in September, I had the good fortune to sit down with Blake Lange of Philips City Farming. The below is an excerpt from a lengthier article to be published in the January (Issue 12) of Urban Ag News.

JP: Blake, thanks for sitting down with me.

What’s with the pink?

BL:

(Laughs) What a funny question. So typically what we see in the industry is a lot of blue and red diodes mixing together and creating a pinkish or purplish hue. Humans see light differently than plants do and plants have a broader sensitivity to light than humans do.  The human eye is especially sensitive to green light.

We see more red diode use (in plant production) because they have been found to be more efficient than the blue light and have a longer lifespan. So again to the human eye, that combination appears to be pink.

The red and the blue mixing, that creates the pink. That’s color mixing. We see that typically if you look at an architectural lighting installation where they want to create a pink effect on the facade of a building – what you would do is turn the intensity of the blues and the reds together and get that pink facade.

JP:

How does one adjust the light “recipe” for any given crop in a fully-enclosed indoor vertical farm grow environment?

BL:

First is to understand what the crop variety being grown is. Typically, most of the growers Philips is working with know what they want to grow. They know who the (plant) breeder is they want to work with. They have the space that they’re growing in. So what we’ll do is come in and understand that unique situation and design according to that specific crop and grow configuration.

In the event, though, that the customer does want to take a look at growing different crops, what we would try to do then is create a system that is applicable for various crops. Meaning, if they wanted to grow basil and bok choy for example, we would try to design that system so that they could have enough light (photons) to grow both crops within the same design set-up.

What I try to stay away from is dimmability, because with that light fixture you want to be operating at 100%. If you’re operating at only 60% for the reds, you’re wasting 40% of the red (diode) capacitywithin that luminaire,  now you’ve overpaid for that system.  There is also additional cost for the dimming system.  Rather, I would like to present to you the system that you can use at 100%, at full capacity, to optimize the efficiency and make your investment dollars make the most sense.

If we were looking at a system where you would have that (light-adjusting) flexibility, typically you would have a building management system or a Priva-like system that manages all your systems: your climate, your irrigation, your lights, your CO2 and manages other infrastructure you have on-site. You have the hardware in place and the software on the back-end and now you are able to say, “I want to operate this cell, rack one, layer one at 60% red and 40% blue.”        

JP:  

What percentage of start-up costs (as a fully-enclosed indoor vertical farming operation) will be for lighting?

BL:

I’m seeing anywhere between 30% to 50+% of capital investment going into the lighting system and infrastructure, which is significant. That varies depending on the size of the facility, the space usage, the crop, the objective of the growers, etc. These start-up cost would be seen in a full system design for leafy greens and herbs typically.