Building a High Tunnel for a Flower Farm: What I Wish I Knew Before Starting
If you're a flower farmer thinking about adding a high tunnel to your farm, there are a lot of decisions to make before the first hoop ever goes into the ground.
How big should it be?
Where should you put it?
Do you need concrete?
How tall should the sidewalls be?
Where should the fans go?
What about irrigation?
And perhaps the biggest question:
How much is this thing actually going to cost?
I'm currently working through all of those questions myself.
I'm a fresh-cut flower farmer in Central Texas, growing in Zone 9A, and this is my sixth year of flower farming. This is also my first year building a high tunnel.
My goal is to use it for fall 2026 through spring 2027, Lord willing.
And because I'm still in the early stages of construction, I wanted to document what I'm learning while it's fresh in my mind.
This isn't a "here's everything you need to know" guide.
It's a "here's what I'm learning as I build my first high tunnel" guide.
If you're considering one for your own flower farm, hopefully some of these lessons will help you think through your project before you spend the money.
What Is a High Tunnel?
Before we get into construction, let's talk about what a high tunnel actually is.
A high tunnel is different from a traditional greenhouse.
For my farm in Central Texas, I wanted something that would help me manage growing conditions without trying to keep the entire structure warm all winter.
We're already dealing with plenty of heat here.
My goal isn't necessarily to keep everything warm all the time.
Instead, I want a structure that can help me manage the growing environment through changing seasons.
That's why I chose a high tunnel rather than a greenhouse.
High Tunnel vs. Greenhouse
The simplest way I think about it is:
A greenhouse is generally designed around maintaining a controlled growing environment, including supplemental heat when necessary.
A high tunnel relies much more heavily on passive heating, ventilation, and environmental management.
For my Central Texas flower farm, I don't need a structure designed primarily around keeping things warm.
I need something that can help me grow through our challenging seasons while allowing plenty of airflow when temperatures rise.
1. Talk to Other Flower Farmers Before Buying Your High Tunnel
If I could go back to the very beginning of this process, this is one of the first things I would change.
I would talk to other flower farmers before shopping for a high tunnel.
I initially started looking online and tried to figure out the size and configuration myself.
I even built out a large high tunnel in an online shopping cart and thought I had a pretty good idea of what I wanted.
Then I started talking to other farmers.
And they gave me one piece of advice that really stuck with me:
Once you have a high tunnel, you're probably going to want more space than you think you need.
That completely changed how I thought about the project.
Instead of asking:
"What's the smallest high tunnel I can get away with?"
I'd encourage you to ask:
"How much growing space am I realistically going to wish I had five years from now?"
Talk to farmers who are actually using high tunnels.
Ask them:
What size did you buy?
What do you wish you had done differently?
How tall are the sidewalls?
Where did you put your fans?
How wide are your doors?
What kind of irrigation did you install?
What would you change if you built another one?
Those conversations can save you from expensive mistakes.
2. Get Multiple Quotes for Your High Tunnel
One of the biggest surprises for me was how different the actual price could be from the number I initially had in my head.
I originally looked at a high tunnel kit online and built out what I thought I needed.
Then I contacted the company and learned that my project required a private quote.
The final quote came in considerably higher than the budget I had originally anticipated.
We were able to work with the company to bring the price down, but it was still toward the high end of what I had planned.
That was discouraging.
So I started looking at other options.
Eventually, I found someone relatively close to me who builds and installs high tunnels themselves.
I ultimately chose to have a local builder install mine.
That brings me to another important question.
3. Can You Actually Build the High Tunnel Yourself?
This is something I would seriously consider before purchasing a kit.
Do you have the labor, equipment, time, and physical help necessary to build it?
I ultimately decided not to build mine myself.
Part of that was simply capacity.
I didn't have the manpower or physical labor available to put the entire structure together myself.
And that's okay.
The cheapest high tunnel kit isn't necessarily the least expensive option once you account for:
Labor
Equipment
Time
Mistakes
Repairs
Your own physical energy
Before buying anything, figure out what installation will realistically look like for you.
4. Think Carefully About High Tunnel Location
Another major consideration is where you're going to put your high tunnel.
Think about:
Soil
Drainage
Wind
Sun
Access to water
Electricity
Equipment access
Future expansion
How you'll move soil and compost
How you'll move equipment in and out
Fortunately, the area where I placed mine had already been maintained for several years.
The soil had been worked and cared for for about three years before the high tunnel went in.
That meant I wasn't starting with completely neglected soil.
Prepare Your Soil Before Construction
If you know where your high tunnel is going to go, don't wait until after construction to think about the soil.
Get the soil ready beforehand if possible.
Once that structure is installed, you'll have a much more defined growing environment.
Think through your beds, walkways, compost, irrigation, and soil amendments before everything is in place.
5. Think About How Your High Tunnel Will Be Anchored
This was another area where I received conflicting advice.
At first, I was told that the posts could simply be driven into the ground.
Then I spoke with another farmer who strongly recommended concreting the posts.
Because we experience high winds here in Central Texas, I ultimately chose the more substantial anchoring method.
My builder concreted the posts, including the tubing that goes into the ground.
The result is a much more substantial structure.
Consider Your Local Wind Conditions
Your anchoring strategy needs to make sense for your climate and site.
If you're in an area with strong winds, storms, or other severe weather, this is not something I would make a casual decision about.
Talk with your builder and other growers in your area about what has worked for them.
6. Plan Your High Tunnel Perimeter
Another thing I had to think through was what happens around the perimeter of the tunnel.
I wanted to put plastic around the outside edges so that grass wouldn't grow directly against the structure.
But I made a purchasing mistake here.
I bought plastic that was 15 feet wide by 100 feet long.
Looking back, I think I would have chosen a different size because I also want to use plastic for the walkways inside my high tunnel.
I may change my mind about that, but it taught me something important:
Think through all of the places you'll need a material before ordering a large quantity of it.
Measure first.
Then buy.
7. Plan Your High Tunnel Ventilation Carefully
This is one of the details I hadn't fully understood before beginning the project.
Your ventilation system needs to work together.
I learned that it's helpful to think about where your fans will be located in relation to your vents.
In my design, the fans are on one side, while the opposite side can eventually have vents that help create airflow through the structure.
We won't have those vents immediately, but we may add them in the future.
Why Airflow Matters in a High Tunnel
This is especially important in a warm climate like Central Texas.
A high tunnel can get hot.
Very hot.
You don't simply want to build a structure that traps heat around your flowers.
You need a way to move air through it.
That's why I'm paying close attention to:
Roll-up sides
Fans
End walls
Future vents
Shade cloth
8. Think About Where Your Fans Are Going Before You Build
One mistake I may have made was placing my fans farther away from where I expect to have electrical power.
We'll see how that works out.
But it's another example of something I wish I had thought through earlier.
Before your structure is built, map out:
Where will my power be?
Then think about:
Where will my fans, irrigation equipment, lights, and other electrical components be?
It's much easier to plan this before construction than after.
9. How Tall Should High Tunnel Sidewalls Be?
This was another major conversation between me and my builder.
I received advice from other flower farmers that I needed more height along the sides.
For my purposes, I wanted approximately 5–6 foot sidewalls.
Why?
Airflow.
Those roll-up sides are an important part of allowing air to move across the plants.
In a warm climate, ventilation isn't something I want to overlook.
The taller sidewalls also give you more room to work and can make the structure feel much more usable.
10. Make Your High Tunnel Doors Large Enough for Farm Equipment
This is one of the things I'm particularly glad I thought through.
My end-wall doors are large enough for my tractor.
That's important because I want to be able to:
Bring compost inside
Amend the soil
Move equipment
Work the walkways
Maintain the growing area
The original kit I was considering would have had much smaller doors.
That might have been fine for a backyard gardener.
But for a working flower farm, I wanted equipment access.
Think about the largest piece of equipment you'll ever want inside the tunnel—not just what you'll need on day one.
11. Don't Forget Shade Cloth in a Hot Climate
Because I'm growing in Central Texas, I'm planning to use white aluminum shade cloth over the top of my high tunnel for much of the growing season.
I'm not particularly concerned about keeping everything warm.
My bigger concern is excessive heat.
That's an important distinction for growers in warmer climates.
If you're in a colder climate, your high tunnel strategy may look very different from mine.
Your climate should influence:
Shade
Ventilation
Heating
Frost protection
Crop selection
Planting dates
12. Plan Your Irrigation Before Planting
Another project I'm currently working through is drip irrigation.
I'm using IrrigationKing for my irrigation system.
My high tunnel is approximately:
100 feet long × 30 feet wide.
That gives me a substantial amount of growing space.
I'm planning on five growing rows, each approximately 100 feet long.
That's a lot of flowers.
And that's also a lot of irrigation to plan.
Will You Need Multiple Irrigation Zones?
One thing I'm still working through is whether I'll need two irrigation zones.
That's something I'm figuring out based on the size of the tunnel and how much water the different areas will need.
Before you install your irrigation, think through:
How many beds you'll have
How long the beds are
Water pressure
Flow rate
Number of drip lines
Crop water requirements
Whether different crops need different watering schedules
Planning this before planting will save you a lot of headaches.
13. Make a Crop-Planning Spreadsheet
One of the most useful things I've done during this process is create a spreadsheet.
I listed all of the varieties I plan to grow.
Then I calculated how much growing space I have.
From there, I divided my varieties according to the square footage available.
That helps me answer questions like:
How many plants do I need to fill this bed?
and
How much space should I give each variety?
I initially thought I might not have enough room.
Now I'm starting to realize I may actually have more space than I expected!
That's another reason crop planning matters.
A spreadsheet can help you see the actual capacity of your growing space before you buy hundreds of seeds or plants.
14. Remember That High Tunnels Are BIG
Here's something I genuinely didn't think through enough:
High tunnels are really tall.
Mine is approximately 17 feet tall.
And 17 feet is much taller than you imagine when you're looking at a flat drawing or a website description.
Once it was standing on my farm, I realized just how large the structure actually was.
So when you're choosing your location, don't only think about the footprint.
Think about the visual height.
Ask yourself:
What will it look like from the road?
What will it look like from the house?
Will it affect the landscape?
Will it cast shade?
Will it change the view?
Will large equipment be able to access it?
A 17-foot structure is a major addition to a farm.
15. High Tunnel Style: Gothic vs. Round
There are different styles of high tunnels.
Two common shapes you'll encounter are:
Gothic
Round
For my farm, I'm using a round-style high tunnel.
One of the reasons is that I don't have to design around a significant snow load.
In areas where snow accumulation is a major concern, growers may choose different structural designs.
Your climate should play a major role in deciding which style makes sense for your farm.
16. Plan for Frost Protection
Even though Central Texas has relatively mild winters, we still get occasional hard freezes.
I'm anticipating needing frost cloth over my flower rows around mid-to-late January, although the exact timing can vary from year to year.
This is another reminder that a high tunnel doesn't necessarily mean your plants are completely protected from winter weather.
You'll still need to understand your local climate and have a plan for unusually cold temperatures.
17. Start Your Crops Before the High Tunnel Is Finished
One of the interesting parts of building a high tunnel is that your crops don't necessarily wait for your construction schedule.
While the high tunnel is being built, I'm already starting my fall-planted crops indoors.
I'm using seed trays and cold stratification where appropriate so that the plants will be ready to go into the high tunnel when the structure is finished.
For example, I'm planning to start my ranunculus around October 1 and move the plants into the high tunnel after germination.
Hopefully, the tunnel will be ready by then!
This is another reason having a crop calendar is so important.
Your construction timeline and your growing timeline need to work together.
18. What I Would Think Through Before Building a High Tunnel
If you're considering your first high tunnel, here's my current checklist.
Before purchasing
☐ Talk to several experienced growers☐ Determine the size you actually need☐ Get multiple quotes☐ Decide whether you'll build it yourself☐ Calculate installation costs☐ Research your local climate requirements
Before construction
☐ Prepare your soil☐ Choose the location☐ Plan equipment access☐ Decide how you'll anchor the structure☐ Plan electrical access☐ Plan fan locations☐ Plan ventilation☐ Determine sidewall height☐ Decide on door size☐ Plan irrigation
Before planting
☐ Create a crop spreadsheet☐ Calculate square footage☐ Determine plant quantities☐ Plan irrigation zones☐ Plan walkways☐ Plan shade cloth☐ Prepare frost protection☐ Start crops according to your planting calendar
What I Wish I Knew Before Building My First High Tunnel
I'm still in the middle of this project.
The tunnel isn't finished yet.
So I don't want to pretend that I have everything figured out.
But that's actually why I wanted to document this process.
I'm learning that building a high tunnel isn't simply:
Buy tunnel → put tunnel up → plant flowers.
There are dozens of decisions happening around that process.
And some of the most important decisions happen before construction begins.
Talk to farmers.
Think about future growth.
Measure your space.
Plan your equipment access.
Think about airflow.
Think about water.
Think about electricity.
Think about how tall the structure will actually look.
And most importantly, think about what you want this tunnel to accomplish for your farm.
For me, this high tunnel is about extending my growing season and giving me another tool to grow beautiful flowers here in Central Texas.
I'm sure I'll make mistakes along the way.
But that's part of farming.
You learn.
You adjust.
And then you plant another season.
Want to Ask a Flower Farmer Your Questions?
When I first started flower farming, one of the things I wanted most was simply someone to ask questions.
Sometimes you don't need a 300-page farming book.
You just need to be able to ask:
"What is this?"
"Did I do this wrong?"
"What should I do next?"
That's why I've created a free flower farming community and monthly live meetup where flower growers can come ask questions and learn alongside other farmers.
[Join the free flower farmer community →]
And if you'd like to see this high tunnel project as it continues, follow along here at Sunny Hill Flower Farm.
I'll be sharing what happens next—and eventually I'll come back with another update showing you how the finished tunnel turned out.
Happy growing! 🌱
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