How to Build a Greenhouse

How to Build a Greenhouse

So, how do you turn a horse ranch into a working hemp farm, ready for 12,000 plants, in just 2 and a half months? Short answer- not easily. But, with the help of enough friends and family, we did it!

Our critical deadline was to be ready to start seeds in a heated greenhouse, in time to put the plants in the field on June 1, and harvest during August and September. We had to be able to harvest the full mature flowers before the first serious freezes and snows. This would turn them into mush, and we would lose our considerable investment and five months of labor. 

Our first major task was to remove the existing corrals, fencing, and gates. 

fields with fences and gates

There were still 3 horses left on the property, as we started. We kept shuffling them around as we worked on different areas.

people petting horses along fence

We had ordered a 30’x60’ greenhouse package, to be delivered and ready for us to assemble. 

greenhouse delivered in ready to assemble pieces

Here's where the greenhouse will be built.

We needed to scrape off years of packed manure, and clear a pad for the greenhouse, and a road on each end.

This is what it looked like on the first day we wanted to build, but it quickly turned to mud.

snowy farm outbuildings


The soil is mostly clay, unfortunately. Instead of fluffy soil or dirt. Clay has an unending cycle of being sticky, sloppy mud when wet, then like concrete when dry. 

muddy corral

Next we set up batter boards and a transit to lay out locations for the steel posts.

men making post level and plumb

We started to drill the holes, and it seemed to be fine. Then came our first realization of how hard the packed clay could be. The six inch steel auger snapped in half as we tried to pull it from the bottom of the hole. Time out to go purchase another.

broken auger

We called ourselves the 1/16” crew. We laid out the posts on 4’ center, then plumbed both ways, and set them all to the exact same height, so it would be easy to set the trusses on top.

carefully making the posts level and plumb

We kept adjusting the aspects until they were essentially as perfect as possible. 

Once all the posts were set and the concrete dried, we laid out the truss members and started to assemble them.

laying out the trusses


We were anxious to see if all if our meticulous work on the posts would pay off as we set the first truss. And we were elated! It sat on the post perfectly.

Then we began production, and securing the trusses in place.

4 trusses up


Next, attaching the lateral girts to ensure that the trusses stayed plumb and evenly spaced. 

building the greenhouse

The end wall, steel framing, and poly vinyl clear siding. We chose 8 foot wide sliding doors so our UTV could drive through the structure.

greenhouse door

Next, adding the rollup side curtains. This allows us to control the airflow across the plants and adjust the inside temperature.

roll up curtains on the greenhouse

The next chore was to install a propane heater in the trusses. When the seeds first go into the potting soil, it’s critical that the seeds and seedlings stay warm for the first 6 weeks of life.

lifting the propane furnace with the tractor bucket

The next project was to cover the roof with plastic sheets. We chose a special 6 mil plastic that filters out harmful UV light, and evenly disperses the sunshine. This takes 2 layers, which creates an air bubble between them, continually inflated by a separate fan. The first step is to lay the plastic on the ground.

Then the leading edge is secured with ropes, which are thrown over the top and slowly, carefully pulled over and secured in a special channel. Everyone helped, even the kids.

child pulling rope to pull plastic over greenhouse

pulling the plastic over the greenhouse frame

Pulling the plastic layers over the top had to be coordinated with the wind. Each night through mid morning, the wind blows steadily down the canyon from the east. Then, there is a brief lull before the wind blows from the west until evening. Too much wind and you can lose control and damage the 50’ x 70’ flapping plastic.

greenhouse with plastic secured 

At last we are ready to begin prepping the inside for the seeds. This is the beginning of the fun part. 

woman enjoying the view from the completed greenhouse.

Next week, all about starting the seeds. 

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