Advice For Commercial Greenhouse

I’m constructing a 30’x96’ high tunnel on our hemp farm. We farmed 10 acres of biomass last year and an acre of flower that got hit bad by caterpillars and bud rot which is why we want to try the greenhouse for flower production.

I’m needing some advice on optimal plant layout for the greenhouse and whether I should try growing in the ground or in containers/bags.

I’d like to keep costs down as best I can so growing in the soil was my first thought but when I look at the cost of compost and amendments for almost 3,000 Sq ft, I’m starting to think containers might not be too bad. Then whether or not to trellis entire rows or individual plants, just let them grow with some topping, or no training at all. All this has got me questioning my assumptions on best management practices.

Any help brainstorming ideas would be appreciated. Thanks!


Continue to harvest outside and use greenhouses for clone / veg production.

Solve the Caterpillar problem using predatory insects like Ladybird Beetles, Anairetes alpinus (Tyrannidae), wasp (Vespidae); mantid (Mantidae); Paraponera ant (Formicidae) , jumping spider (Salticidae); stink bug (Pentatomidae).

There is no price bonus with greenhouse hemp vs outdoor like with rec cannabis.


The catepillars come from moths, so you would have to screen your hoophouse carefully. Hemp is also a late summer and early fall crop, when it is harder to grow under plastic, because it gets so hot. You might consider a light deprivation high tunnel, where you use a cover to induce early season flowering. It brings an earlier crop that is easier to sell by being early, and you can grow in the spring and early summer when it is not as hot.

And fwiw in my limited experience I have found container grown hemp to be much lower in cbd than crops in the ground. I am in illinois, not too far away.


Honestly man with prices going the way that they are, I would completely back out of trying to grow any better than you are with greenhouses and indoor facilities. It’s just not worth it. Many farmers still have great hemp flower from 2 years ago they produced that can barely be sold. I would just use a heavier IPM treatment, and try to use strains that are more resistant to bud rot. There’s plenty of strains that can be rained on every single day and not rot

Yeah, I’ve seen some uni studies on using 40% shade cloth as bug netting for larger pests like moths but small ones like thrips can still get in. I’ll add predatory insects if that becomes an issue.

I’ll look into the light dep system. Prbly be better to at least get in two crops to justify the high tunnel and light dep system. I’ll have enough active ventilation for complete air exchange in a minute, about 8k cfm of HAF fans, and shade cloth. Just hoping to get the temp in the tunnel to the same as outside.

Maybe long raised beds with a soilless living soil mix could work instead of the containers or banding compost/amendments into the rows and not broadcast it.

Sealed GH and run some boutique hemp.


I know what your talking about with guys sitting on old product. I’ve talked to a few of them and most didn’t have a buyers lined up. I have 2 retail stores where I sell our own tinctures but not our own smokable flower. We’ve been steadily selling more flower from other companies over the last year, so we’d like to switch our customers over to our own stuff. I also have a buyer for my untrimmed smalls for hemp cigarettes, they’d buy around 2-300lbs of my harvest.

We averaged 1.5 lbs per plant on 11 acres on our first year with a ton of issues will be correctly this next season. So I’m hoping to hit 3 lbs. per plant in the high tunnel for a total of 375-400 total lbs off 125 or so plants, even more if I go for a light dep system.


If you have to shade the sun to control the high tunnel, it seems like that would affect the growth of the plants. But idk how else you could keep it cool in there. I get over 50 degrees of temp gain in my greenhouse with winter sun. By the time the summer heat hits, it is miserable in there, even with the sides rolled up.

I was concerned about that too but from what I’ve read there should still be enough light coming through a 30-40% shade cloth. That wasn’t specifically for cannabis but more general horticultural

Shade cloth will be detrimental to yield. In practice once you get automated light dep set up and all the other crap in the attic you cut light down by half…e.g. if your covering transmits 50% light, only 25% will be seen at the canopy in practice. What is your climate like at both extremes? I run thc greenhouses where the extreme temps are 35f-120f. A 100’ long house is pushing it for boutique cannabis. My main house is 100’ long, but has the airflow for 2 exchanges per minute with a large wetwall and an extensive mist system.

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Evaporative cooling doesn’t work here. It’s too humid.


I am a horticulturalist. Compared to most horticultural crops grown in houses, cannabis is much more light hungry. In general 1% loss of light translates to 1% loss in yield. In practice I just change grow style. Once I’m dealing with a house that is sub 800 umol, I no longer grow trees and grow like an indoor with a 24" effective canopy depth.


Thanks for the insight on the shade cloth. My extremes are prbly 30f on the low end and 100f on the high, maybe a few days around 105f. I wasn’t planning on heating the tunnel and just trying to do either one big harvest or a few with the light dep system.

I thought of doing a true greenhouse but we can’t really take advantage of evap cooling with consistent 90-100% humidity during the summer. From my understanding there needs to be a lower RH for that to work but I could definitely be wrong. I also came into this project with a tight budget but if can get multiple harvests, that might pencil out a bit better for a bigger budget but idk the true cost per sq ft for a cooled and heated greenhouse in my area.

I didn’t even read the screen name. In MO, I personally would run a high pressure fog system. Having run houses in a similar environment, FL, I know it works. Fog is installed on every truss and staged to come on using temp and humidity triggers. Most people are amazed by how much the air dries out as it heats up running down the house.

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As a proof of concept, and as long as your municipality allows it, I would just build a pvc hoop house and run it positive pressure. For your climate, I would not go over about 60 feet in length for the house. You’re trying to remove +/- 300 btu per square feet fighting with the sun.

Edit: As long as you have a good sized crew, you can also manually pull dep cloth over a hoop house. Sucks to do every day, but worh it compared to the cost of automated for a proof of concept.

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Just curious, how do you know the moisture of the fogger won’t grow mold or mildew on your buds?


If I were to go all in and do a fog system in a poly covered high tunnel, what length would you suggest?

I’ll have 5 full time guys on the farm to help out when needed but they’ll be mostly taking care of our field stuff but luckily weeding will not be an everyday thing anymore. We bring in more for planting and harvesting. Myself and another person will be doing the day to day on the tunnel. Automation might be best since I also do all the scouting and compliance stuff for our fields. Kinda why I was thinking of planting in rows in the soil with drip tape, just keep it simple

@Autumn_Ridge_Hemp I know how to control the internal ph of the plant to make it highly unlikely to harbor fungi…basically don’t create an environment the fungi want to live in.


That’s quite a bit of math to figure out. You need to start with your acceptable temperature delta from one end to the other and work from there…more cfm allows longer house. My flower houses run a 10 degree delta, but I have a wetwall in a dry climate, so my entering air temp is never over 80.


Gotcha. I’ll look into figuring it out based on my variables. Thanks for the insight, very much appreciated.