High Tunnel Gardening: What You Need to Know to Grow Successfully

Are you familiar with the term high tunnel?

If you’ve been gardening very long, you may have heard commercial farmers or even avid homesteaders talk about their high tunnels.

A ‘high tunnel' is a large cold-frame hoop house or greenhouse which is usually unheated. They use the sun to warm the crops and can be great for those who grow food in colder climates.

I’m going to walk you through how a high tunnel works, what grows best in a high tunnel, how you compensate for poor weather by using a high tunnel, and more.

Here’s how you can incorporate high tunnel production into your gardening:

How Does a High Tunnel Work?

A high tunnel is an elongated structure which covers a large area of bare soil. It is usually constructed out of metal or wood.

The structure is covered in one to two layers of greenhouse material. The greenhouse material could be hard plastic sheeting or thick sheets of durable plastic, which comes in rolls.

It doesn’t have a concrete pad beneath it. Instead, the structure is placed over bare land.

There are no lights or other fancy equipment to keep the high tunnel warm or to feed the plants artificial sunlight.

Instead, the structure depends on natural sunlight to keep the inside warm and meet the needs of the crops.

You don’t depend on any special gardening technique when growing in a high tunnel. There are no raised beds or grow tables.

Instead, the crops are planted directly into the ground and grow as they would in any typical in-ground garden.

The difference being, the high tunnel protects the crops from unpredictable weather such as frost, high winds, or an unexpected cold snap.

It’s also a great method of protection for your plants from pests.

High tunnels are great for many reasons, but one of the best reasons many commercial farmers use them is because they can lengthen the growing season of a specific crop by up to a month and bring the harvest in up to a month earlier.

This lengthening of the season enables farmers with high tunnels to be able to sell crops earlier, as well as later than most of their competition.

How Can I Incorporate a High Tunnel into My Garden?

planting in a high tunnelplanting in a high tunnel

If you aren’t a commercial farmer, you may not see the point in incorporating a high tunnel into your garden.

Yet, if you’re someone who likes to grow their own food, this could be a way to grow crops almost year-round (depending upon the climate where you live.)

Not only does this equate to a healthier diet for you and your family, but it will also help save money at the grocery store.

You can purchase a prefab high tunnel to make construction easier, or you can choose to build your own.

If you live on a smaller chunk of land, you may prefer to build your own high tunnel structure because you can make it a more exact size to suit your property.

The most important aspect of installing a high tunnel is to make sure it stays perpendicular to the typical wind pattern in your area.

If you don’t, the tunnel could easily become damaged.

Consider the layout of your homestead, when planning where to erect the structure.

Once you decide you’d like to grow more crops on your property for longer periods, and you find the perfect high tunnel for your set-up, you treat the crops as you would if they were in the ground in the open air.

It’s important to make sure the crops are watered properly, fertilized regularly, and the weeds are kept under control.

If you can do this, you should find great success in growing crops inside a high tunnel.

What Grows Well in a High Tunnel?

plants that grow well in a high tunnel is asparagusplants that grow well in a high tunnel is asparagus

You’re sold on the idea of a high tunnel, but what should you grow? The wonderful news is you can grow basically anything you want.

You can grow:

In my own experience with a high tunnel, I was fascinated at how well my tomatoes did.

High tunnels are great at protecting your crops from cooler weather, but they’re also wonderful for adding the heat to the crops which thrive in it.

If you’re wanting to boost your tomato and pepper crop, a high tunnel could be the perfect solution.

As a general rule of thumb, as long as the soil is above 55 degrees Fahrenheit, and you’re getting around 10 hours a day of sunlight, you’re good to grow anything you desire.

If the soil is cooler, or you aren’t getting as much sunlight, it’s best to stick with leaf lettuce, spinach, and root crops.

Heartier vegetables will be necessary for cooler conditions as they would be equally suited in any other planting scenario.

How to Grow Crops in a High Tunnel

High tunnels are simple to grow in, and they make gardening easier. I grew crops in a high tunnel for almost four years before moving to our new, larger farm.

It was great at protecting the crops from pests, frost, and yielding large quantities of food for my family. Though high tunnels are wonderful producers, the biggest mistake many people make is not caring for it like they would a typical garden.

Be sure to prep your soil as you would for your garden, keep the planting area cleaned out when you aren’t growing in your high tunnel, and follow similar planting times for your planting zone as you would for an outdoor garden.

You can plant crops up to a month earlier in a high tunnel without an added heat source in most cases. Obviously, if you’re planting tomatoes in your high tunnel a month earlier, keep an eye out for unusually cool temperatures as they’re sensitive to cooler weather.

If you’re running behind, you can plant crops up to a month later as well because they’ll be protected from potential weather fiascos in a high tunnel.

Otherwise, it’s as if you were planting anywhere else. You should have approximately three planting cycles in a high tunnel.

Plan on planting in early spring, summer, and for the fall. If you live in an area with a warmer climate, you may be able to grow year-round.

I live in planting zone seven and was able to grow heartier crops (such as spinach, lettuce, and radishes) throughout the winter.

High tunnels are also a wonderful place to start seeds and harden off seedlings before moving them outdoors.

Be prepared to use a supplemental heat source if you choose to start seeds in your high tunnel. Check out number 9 in our article on rocket mass heaters to see an idea for a heat source. Alternatively, if you do have power in your high tunnel, you could install a garage heater.

During the day, natural sunlight should be enough to keep them warm and safe.

Nights still get too chilly in most areas when starting seeds, and they’ll need a boost of heat to keep the seedlings from freezing.

Pollinating High Tunnel Crops

When growing crops in a high tunnel you may or may not have thought about pollination. This was a concern of mine when I first started raising crops in our high tunnel.

I was pleasantly surprised by what I found out. Though I began pollinating some of my plants by hand, I soon realized I didn’t need to.

I wrongly assumed pollinators wouldn’t come into my high tunnel. Oddly, I found they were drawn to it. I left the windows and door open on hot days and when I’d walk in the bees were buzzing all around my crops.

However, if you find you have a different experience and pollinators are avoiding your high tunnel instead of embracing it, don’t fret. You can pollinate your plants by hand. It’s a simple process and only takes a few moments of your time when you’re in the high tunnel caring for your crops.

Troubleshooting the Weather

protect plants against frost with a high tunnelprotect plants against frost with a high tunnel

Having a high tunnel can help you beat the weather in many ways, but you still must be prepared for the curveballs.

Keep an eye on the weather to be alert if a random hard freeze is headed in your direction. It may be necessary to add a temporary heat source not to lose an entire crop.

For instance, if a freeze is coming earlier than usual, and you still have tomatoes growing in your high tunnel, either harvest all the tomatoes ahead of the freeze (green or not) or add a heat source for the night such as a propane heater.

Most of us concern ourselves with our crops freezing, but you should be equally concerned about the crops receiving too much heat during the summer.

High tunnels should have vents in the ceiling, windows, and a door to help control airflow. During the steamy summer days, be sure to let air flow through your crops to keep them from cooking in the heat.

Being mindful of the weather will help your growing experience in a high tunnel be pleasant instead of one of frustration.

You’ve learned a great deal of information on how and why you may want to incorporate a high tunnel into your garden.

They’re handy in helping you make more money from your homestead or in helping you save money when feeding your family.

It’s our hope, this information will help you to become more self-sufficient over time and have more time digging in the dirt too.

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