Ultimate Guide to Using Low Tunnels in the Garden

Low tunnels are easy-to-use and affordable. They allow you to get crops in the ground earlier in the spring and produce longer into the fall.

If the thought of building a high tunnel or hoop house intimidates you, this guide is for you. Learn everything you need to know about low tunnels to increase productivity and yields this season. 

What Are Low Tunnels?

Low tunnels are temporary, moveable structures like mini hoop houses or greenhouses. They're made of EMT hoops covered with plastic, fabric, or netting.

These small tunnels typically stand only a few feet tall and cover plants directly in your garden beds. They protect plants from harsh weather and pests, and extend your growing season by weeks or months.

Like cold frames, low tunnels make a great DIY project. Use them in an uncovered growing space in backyard gardens or market farms and move them as needed. Layer low tunnels inside of high tunnels to create a year-round microclimate.

While some planning goes into where and how to build a low tunnel, the setup, breakdown, and use are simple. 

Our low tunnel kits stand out by being much easier to move. Unlike most tunnels that must stay in place or be fully broken down in order to move to another plot, ours can be quickly shifted to different garden areas. This saves you time and lets you protect various garden areas throughout the season.

Read Cut Flowers for High Tunnels: A Beginner’s Plant Guide if you want to specialize in cut flowers. Most of the same principles that apply to high tunnels would apply to low tunnels.

At its core a low tunnel system (LTS) consists of: 

• Hoops that can be of various heights and made from different materials 

• Changeable coverings that each serve a different purpose

• Anchoring systems with strength and durability selected for your region

A comparison shot of 6 mil. plastic, frost blanket, and white mono shade cloth covers used for low tunnels.

Benefits of Using Low Tunnels

Low tunnels are a low-cost way to extend the spring and fall seasons. Covered soil warms up quicker in the spring - which means you can direct sow and get transplants in the ground sooner. This results in an extended farmer’s market season or more fresh food on your family’s table. Growers may get four to six more weeks on the front and tail ends of their season by using a low tunnel.

Low tunnels aren't only for extending the season. They also: 

• Offer crop protection from temperature fluctuations, frost, harsh wind, snow, and pests. 

• Warm the soil, offering better root development and growth. 

• Decrease the risk of fungal disease and damping off in the spring. 

• Are inexpensive compared to a high tunnel or hoop house. 

• Scalable for small-scale homesteads, market gardens, and beginner backyard growers. 

• Make it easy to experiment with new crops.

Types of Low Tunnel Coverings

We always recommend electrical metal tubing (EMT) for hoops.

EMT is durable, able to withstand snow loads and heavy winds, and easy to bend with a hoop bender. Its also a cost effective option and usually available at local hardware stores. If you're using a hoop bender for the first time, make sure to check out Bending Hoops for Hoop Houses. 

When the risk of spring frosts has passed, swap out plastic and frost blankets for insect netting and shade cloth.

Bootstrap Tip: Save yourself some hassle and layer protective coverings. This gives you two types of coverage at once.

For instance, install insect netting in the spring underneath the frost blanket. When temperatures increase, remove only the frost blanket and leave the insect netting. How Do Frost Blankets Help to Prevent Crop Loss? explores how frost blankets prevent damage. 

VIDEO: How to Make 4-Foot Low Tunnel Hoops | DETAILED Step by Step to a 4-ft Bender

Plastic Covers for Ultimate Cold Protection

You can cut the same durable, 6-mil plastic used on hoop houses and greenhouses to fit your LTS. Plastic is best for overwintering crops like onions, kale, leeks, carrots, and baby head lettuce. Because it fully encloses them, it protects them from snow, wind, and frost while still allowing the sun to penetrate. 

We offer low tunnel greenhouse plastic in a 12’ width and length of either 24’ or 32’. We also offer greenhouse film in larger widths if you want more customizable lengths. Both are highly durable, come with a four-year warranty against UV degradation, and ship free to the lower 48 states in the US.

The plastic cover works like a small greenhouse, trapping heat inside the tunnel. Since there's only a small amount of air inside, temperatures rise quickly. Use these tunnels during winter and early spring, but watch out as seasons change. Sudden warm days can cause harmful temperature spikes that damage your crops.

Using Frost Blanket for Season Extension

A frost blanket keeps heat close to your plants and soil. One or two layers can boost temperatures around your crops by 5° to 10°, depending on how humid it is. This warming effect is like moving your garden half a growing zone south!

Unlike plastic, frost blanket will allow rain to pass through. It can be used on its own or paired with plastic for extreme cold conditions.

Frost blankets come in different weights (0.9 to 4 oz.) for different seasons and growing zones. Choose your frost blanket weight based on your growing season, local climate, and what you're growing.

Bootstrap Tip: Make sure your hoops are properly spaced and secured to prevent the blanket from sagging. If frost blankets touch your plants during a freeze, it can damage them.

Pest Control for Low Tunnel Crops

Stop hand-picking Colorado potato beetles, cucumber beetles, and aphids off your plants. Add a layer of insect netting to the low tunnel and reduce the need for manual labor or pesticides.

Plants such as beans, potatoes, beets, and leafy greens (including arugula and spinach) don't need insects for pollination. You can keep these plants covered with the tunnel the whole growing season.

Step-by-Step: Adding the Insect Netting

Tip: You'll need two pieces of insect netting for complete coverage because it only comes in 6-foot widths.

1. Take two sheets of netting and overlap them in the middle.

2. Temporarily secure the overlap with clamps to keep everything in place.

3. Position the netting so each side barely touches the ground. This helps avoid damage.

4. Leave about 4 feet of extra netting at each end to close the tunnel properly.

5. Fold the extra netting at the ends neatly, like wrapping a present. This keeps it from flapping in the wind.

6. Place a brick or sandbag on the folded ends to weigh them down.

7. Use this same method when working with frost blankets or greenhouse film.

Insect netting can spread heavy rain evenly across your crops and can protect them from rain damage. When you add shade cloth or frost blankets later in the season, keep the netting underneath. This gives your plants an extra layer of defense against bugs.

Customizing Low Tunnels for Specific Crops

Make taller tunnels for big plants like broccoli, cabbage, and cauliflower. This gives them room to grow and keeps bugs from laying eggs through the netting.

For smaller plants like lettuce and baby greens, very low tunnels work fine. Overwintered crops without much leaf growth like onions also need less height. 

How to Build a Low Tunnel

Here are the materials and supplies you'll need to build a low tunnel using our DIY low tunnel kits.

Materials Needed

• DIY low tunnel kit (The 10’ kit includes ¾-inch EMT cross connectors, ¾-inch snap-on clamps, and PDF instructions. The 20’ kit includes everything already listed, as well as ¾-inch screws and splices.)
• 10-foot EMT poles (we recommend 8 for a 10'
• 1 inch x 1-foot rebar pin
• Crescent wrench, socket, or socket on a drill
• Miter saw to cut the EMT
• #8 self-tapping screws
• Permanent marker
• Tape measure
• A friend to help keep the structure level as you assemble it

Step-by-Step Instructions for the DIY Low Tunnel

1. Create Your Hoops: Bend four of the 10' EMT poles into 4' wide hoops using your bender.
2. Start the Frame: Attach one 10' EMT pipe to the top of one hoop using a ¾" cross connector. This becomes your ridge pole. Bootstrap Tip: Have someone hold the hoop upright or push it into the ground to keep it stable.
3. Complete the Basic Frame: Attach another hoop at the opposite end of the ridge pole.
4. Add Middle Support: Space the remaining two hoops evenly between the ends and attach them to the ridge pole.
5. Choose Your Anchoring Method:
• Option A: Place the side supports near the base if using rebar to anchor.
• Option B: Mount side supports about 6" up if pushing hoops into soil.
6. Add Side Supports: Attach the remaining 10' EMT pieces horizontally along each side of the hoops using cross connectors.
7. Add End Supports: Cut two 52" pieces of EMT and attach them horizontally at the bottom of each end hoop.
8. Final Assembly: Mount the end bars above the side supports using two cross connectors at each end.
   

Your low tunnel frame is now ready for covering! Don't worry if the structure seems a bit wobbly at first—this is normal with hand-bent hoops. Once secured with covering and anchored properly, it will become more stable.

Small gaps at the bottom of your tunnel will naturally fill with soil over time, creating a better seal for your plants. This actually helps with airflow and prevents moisture buildup!

Download our comprehensive PDF guide from our website or scan the QR code on your product packaging.

VIDEO: Protect Your Garden in All Seasons: DIY Low Tunnel Setup with Bootstrap Farmer

Tips for Success

• Screw from the side to avoid sharp edges that could tear plastic, netting, or blankets.
• Check all parts, read instructions, and watch videos before starting.
• Get a helper to keep your tunnel level and coverings tight.
• Measure twice, cut once to avoid wasting materials.
• Watch the weather forecast closely so you can swap coverings before big temperature changes.
• Keep detailed notes throughout the season. Record what worked, what didn't, and important dates like when you switched from heavy to light frost blankets.

Best Practices for Using Low Tunnels

To get the best results from your low tunnel, choose the right plants, adjust for weather changes, and adapt your setup as seasons shift.

Crop Selection

Cold-hardy crops and those that need less daylight do best in low tunnels. Good choices include:

• Leafy greens
• Head lettuce
• Brassicas
• Sweet potatoes
• Overwintered leeks
• Bulbing onions
• Scallions

Taller plants like tomatoes, peas, and peppers benefit from tunnel protection in their early growth stages. Low tunnels are light and portable, so you can easily move them to protect different crops as needed.

Managing Temperature and Ventilation

To keep your crops healthy under cover, you must monitor temperature, humidity, air flow, and ventilation. Low tunnels have less air inside, so conditions change faster than in larger structures.

Here's how to manage them:

• Place a thermometer in the soil inside your tunnel to track temperature.
• On warm days, lift the sides of your plastic or frost blanket to prevent overheating and keep soil moist. Lower them before sunset to trap heat.
• On sunny days, add shade cloth to your tunnel. Use either 30% black monofilament (which won't fray when cut) or 50% aluminum white shade cloth. This helps:
  • Lower the temperature
  • Control sunlight
  • Prevent greens from bolting in sudden heat
  • Maintain good air flow
• Switch from heavy greenhouse plastic to lighter frost blankets when moving from winter to spring, or spring to summer.
• For heat-loving crops like sweet potatoes, use thin plastic with slits to create warmth and still allow ventilation.

This article goes in-depth about the different colors and types of shade cloth. Check here for more details on managing growing conditions.

Irrigation System Recommendations and Setup

Set up your irrigation system before installing tunnel hoops to avoid threading through them later. Do this before planting to ensure your seedlings don't go thirsty.

For small tunnel irrigation, use our raised bed kit. For more custom setups, try our greenhouse drip irrigation kit.

Follow these steps:

1. Lay out your drip lines and cut them to the right length
2. Adjust the number of lines based on what you're growing (three lines for leafy greens, one line for summer squash)
3. Connect the lines to the header
4. Connect the header to your main water line
5. Install your hoops and covering after the irrigation is set

Check our instructions for detailed guidance on setting up your system.

Seasonal Maintenance and Adjustments

Fix any damage to your plastic coverings before winter arrives. Check that all clamps work properly.

For winter prep:

1. Replace shade cloth and insect netting with heavier greenhouse plastic
2. Pull the plastic tight
3. Secure the ends firmly

When spring comes, switch to lighter covers that allow more sunlight to reach your plants.

VIDEO: Installing Frost Blanket on Low Tunnel Hoops

Common Challenges & How to Overcome Them

Scaling Down Low Tunnel Design for Homesteaders

The low tunnel kits work great for homesteaders and small gardeners. You can adjust the height and length to fit your raised beds and plants. The clamps make it easy to change coverings based on weather and crop needs. Plus, our design fits perfectly with standard 4' x 8' wooden raised beds common in backyard gardens.

Planning for Year-Round Protection

• Start the season with all supplies - spare parts, clamps, and sandbags to hold down coverings at tunnel ends.

• Choose crops that grow well in your local climate.

• Create a schedule and monitor the weather so you can switch coverings as needed.

Pro Tips for Beginners 

• Start small with just one or two tunnels. This helps you learn how to build them, change coverings, protect plants in bad weather, and remove them for tending crops.
• Take plenty of photos and keep notes on what worked and what didn't. Use this info to make changes next season. 
• Try different coverings and watch how they protect your plants. For example, if your brassicas got bug damage under just a frost blanket, you'll know to add insect netting next time.
• Pay attention to protection levels. Maybe the light 0.9 oz frost blanket wasn't enough for your spring arugula, or the 2.5 oz was too heavy for your turnips.

The more time you spend in your garden, the more you'll notice what works and what doesn't. Low tunnels can grow with you when you're ready to expand.

FAQs About Low Tunnels

What is the best material for low tunnel covers?

We recommend 6-mil greenhouse film for low tunnels. Our film offers:

• Anti-dust protection
• 20% light diffusion
• Four-year rating and warranty

As weather warms up, switch from heavy plastic to lighter frost blankets or insect netting based on what you're growing underneath.

How much does it cost to build a low tunnel?

Low tunnel costs vary based on materials and length. Our 20' DIY kit includes connectors, clamps, splices, screws, and instructions. You can add extras like pipe benders, shade cloth, netting, plastic, and frost blankets. You'll need to buy the EMT and other hoop materials locally.

Basic setups cost about $35 per 100 feet. Premium setups run about $500 per 100 feet.

What crops grow best under low tunnels?

These crops do well under low tunnels:

• Lettuce
• Strawberries
• Mixed greens
• Overwintering onions
• Cabbage
• Broccoli

Can low tunnels be used year-round?

Low tunnels can be used all year. Just keep in mind rainfall, strong winds, and heavy snow when choosing your materials. 

Are low tunnels effective for pest control?

When used with insect netting, low tunnels effectively keep pests at bay. 

How do I ventilate a low tunnel in hot weather?

You can ventilate your low tunnel in several ways:

• Use thin plastic film with ventilation slits
• Pull up the sides and clamp them in place
• Open the tunnel ends by clamping them up

What’s the difference between row covers and low tunnels?

Row covers can work with a low tunnel system or be used on their own for quick frost protection. Low tunnels are more structured setups that extend your growing season for longer periods.

Do low tunnels work in heavy snow regions?

Low tunnels can work in snowy areas, but you'll need the right materials. Local extension offices and universities test methods for different regions. Contact your extension office to learn about successful techniques for your area. Larger gauge materials often handle snow better.

How long do low tunnel materials last?

Low tunnels last indefinitely with proper care, maintenance, and repairs. 

Can low tunnels help with soil health?

Low tunnels can help with soil health by protecting it from erosion and extreme weather. Just make sure to remove the coverings at the end of each season. This allows rain and snow to flush salts from the soil.