High Tunnel Basics for Small Farms

What is a high tunnel?

A high tunnel, sometimes called a hoop house, is a plastic-covered frame with crops growing in the ground inside. It is usually unheated and ventilated by rolling up sides or opening ends. It gives earlier and later harvests and protects crops from rain and wind.

It differs from a greenhouse, which is usually heated and has more controlled conditions. Ask your extension office which one suits your goals.

Start with a small structure to learn. A modest tunnel teaches you about ventilation, watering and pests with a smaller loss if something goes wrong, and you can expand after a full season of experience.

• Rolled-up sides or open ends
• Plastic over a frame
• Crops in the ground
• Unheated by design

How do I choose a site?

Pick a level, well-drained site with good sun, near water and electricity if needed. Avoid low areas where water or cold air pools. Consider wind direction, because tunnels catch wind like sails.

Check the soil with a soil test and ask your extension office about local snow and wind loads. Rules may apply to structures, setbacks and permits, so ask your local zoning and building office what is needed before you build.

Drainage around the tunnel matters. Water running off the roof can pool at the sides, so plan ditches or grading so rain moves away from the structure and does not flood the beds inside.

• Level, well-drained site
• Good sun all day
• Water close by
• Know local wind and snow patterns

What should I know about wind and snow safety?

Structures can collapse under heavy wet snow or fail in strong wind. Follow the manufacturer's instructions for anchoring and snow removal, and do not enter a structure under heavy snow load. Ask a qualified professional for help with large builds.

Keep plastic tight and check anchors regularly. If severe weather is forecast, follow local guidance and keep away from the structure.

Plastic covering lasts only a limited number of seasons and needs replacing. Plan how you will do the work, and ask about the manufacturer's guidance on installation temperature and tension, since a loose cover flaps and wears quickly.

How do I ventilate and manage heat?

Tunnels heat up fast on sunny days, even in cold weather. Roll up sides or open doors and ends to vent, and close in time to keep warmth overnight. Daily attention is part of the work. Wind can also shred plastic that is left loose, so check tension on the cover each season and tighten it as the plastic relaxes.

Plan how you will vent before you buy, whether by hand, by opening end walls or with automatic openers. A tunnel you cannot reach on a hot day can lose a crop.

Consider labor honestly. Tunnels need daily venting and regular watering, so think about who will do it on busy days or when you travel. A tunnel that goes untended in a hot spell can lose a crop.

How do I care for soil and water inside?

Rain does not reach crops, so you must supply water, usually with drip lines. Salts can build up over time without rain to leach them, so ask your extension office about soil testing and management for tunnels.

Rotate crops and add compost. Disease can build up in a covered space, so clean up residue and ask about cover crops and rotation.

Talk to growers near you. Local farmers who already run tunnels know about wind, snow and pests in your area, and many are willing to share what they learned, including mistakes they would avoid.

What crops suit a high tunnel?

Many small farms grow early tomatoes, peppers, cucumbers and greens in tunnels and use cold-season crops through fall and winter. Choose crops by what you can sell or eat and what returns the most value for the space.

Start with one or two crops and learn how the structure behaves through a full year before expanding.

What about cost and programs?

Think in cost categories: the structure and plastic, site preparation, anchoring, irrigation, ventilation, labor, and replacement of plastic over time. Do not rely on any general figure, since prices vary widely by size and region.

Some federal and state programs have supported high tunnels. Ask your local NRCS office or Farm Service Agency office whether programs are available now, what they require and how to apply, since availability and rules change.

Last reviewed: November 12, 2026. Written by the Homestead & Small Farm Editorial Team. See our editorial policy.