8 Pieces of Equipment for a High Tunnel Winter Growing Operation
Sustaining crops in winter requires the right tools. Explore eight essential pieces of equipment, from row covers to heaters, that optimize high tunnel yields.
When winter settles in and the ground outside freezes solid, a high tunnel transforms into a sanctuary for cold-hardy greens and root crops. Success during these dark, freezing months relies entirely on creating a reliable microclimate that buffers against extreme temperature swings. Equipping your structure with the right tools ensures your crops survive the deepest freezes and thrive straight through to spring.
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Preparing Your High Tunnel for Winter Success
Winter growing in a high tunnel is not about heating the entire structure to summer temperatures, but rather about creating layers of protection. As daylight hours dwindle below ten per day—a period often called the Persephone days—plant growth slows to a crawl. The goal is to get crops to maturity before this darkness sets in, then use the high tunnel to preserve them for winter harvest.
Preparation begins in late summer and early autumn with soil preparation and timely seeding. Once the cold winds arrive, sealing any drafts in the plastic film and securing the end walls becomes critical. A well-prepared tunnel acts as a windbreak, shedding heavy snow loads while trapping the earth’s residual warmth close to the soil surface.
Row Cover – Agribon AG-30 Floating Row Cover
Inside a high tunnel, a single layer of plastic is rarely enough to keep tender greens from freezing solid during a deep overnight frost. Floating row covers act as a secondary greenhouse inside your structure, trapping a pocket of warmer air right over the crop bed. This extra layer can raise the temperature around the plants by 4 to 6 degrees Fahrenheit, which often makes the difference between survival and crop failure.
The Agribon AG-30 is a medium-weight spun-bonded polypropylene fabric that strikes the perfect balance for winter growing. It provides 70% light transmission while offering frost protection down to 26°F (-3°C). Unlike lighter covers that tear easily under snow load or heavier blankets that block too much winter sun, this weight is durable enough to withstand repeated handling throughout the cold season.
When purchasing, buy a width that allows ample slack to drape over your support hoops and touch the ground on both sides, where it must be weighted down with sandbags or smooth stones. Keep in mind that wet row cover can freeze to plant leaves and cause frost damage, so keeping it elevated off the foliage is essential. This cover is ideal for growers in Zones 5 through 8 who need reliable frost protection without starving their crops of precious winter light.
- Weight: 0.9 oz. per square yard
- Light Transmission: 70%
- Best For: Spinach, kale, carrots, and hardy brassicas
Support Hoops – Johnny’s Quick Hoops Bender
Laying heavy row cover directly onto wet winter greens invites rot, disease, and frost damage where the wet fabric touches the leaves. You need a sturdy framework of low hoops to suspend the cover just inches above the crop canopy. Strong hoops also prevent heavy condensation or unexpected indoor snow-load collapses from crushing your plants.
The Johnny’s Quick Hoops Bender allows you to mount a steel bender to a workbench or trailer and bend inexpensive 1/2-inch EMT electrical conduit into perfect low hoops. This tool creates uniform, smooth arches that will not snag your expensive row covers. Bending your own hoops is far more cost-effective than buying pre-made wire hoops, which easily bend out of shape under pressure.
Operating the bender requires some physical effort and a solid mounting surface, such as a heavy work table or a sturdy post. It is important to buy the correct bender model for your desired bed width, typically 4 feet for standard high tunnel beds. This tool is a smart investment for growers managing multiple beds who want durable, wind-resistant infrastructure that lasts for decades.
Digital Thermometer – SensorPush HT1 Smart Sensor
High tunnels can experience wild temperature swings, plummeting to freezing at night and overheating on sunny winter afternoons. Guessing the temperature inside your tunnel from the comfort of your living room is a recipe for disaster. Real-time temperature monitoring tells you exactly when to vent the tunnel or when to add an extra layer of row cover.
The SensorPush HT1 Smart Sensor is a compact, highly accurate device that monitors both temperature and relative humidity. It uses Bluetooth connectivity to send data directly to your smartphone, storing history so you can track overnight lows. The sensor is built to withstand the high-humidity environment of a winter greenhouse without losing calibration.
Because Bluetooth has a limited range, you may need the optional SensorPush G1 WiFi Gateway if your high tunnel is located far from your house. Be sure to hang the sensor at plant canopy height rather than eye level to get an accurate reading of what your crops are actually experiencing. This smart sensor is perfect for busy part-time farmers who need instant alerts when conditions reach critical freezing thresholds.
- Connectivity: Bluetooth (WiFi optional with gateway)
- Battery Life: Over 1 year (user-replaceable CR2477)
- Accuracy: ±0.5°F and ±3% humidity
Managing Ventilation and Humidity in Freezing Cold
High humidity is the silent killer in a winter high tunnel. While keeping the tunnel sealed tight preserves heat, it also traps moisture transpired by the plants and evaporated from the soil. This stagnant, damp air creates the perfect breeding ground for fungal diseases like gray mold (Botrytis) and downy mildew.
Venting must be done on almost every sunny winter day, even when outdoor temperatures are well below freezing. Opening the ridge vents or end-wall doors for just an hour during midday allows cold, dry air to flush out the warm, humid air. The goal is to dry the leaf canopy before the sun goes down and temperatures drop again.
Circulation Fan – J&D Green Breeze HAF Fan
When outdoor temperatures are too low to safely open vents, you must rely on internal air movement to prevent condensation from settling on your crops. Horizontal Air Flow (HAF) fans keep air moving continuously, breaking up microclimates of cold, damp air at the soil level. This constant circulation dries the foliage and strengthens plant stems.
The J&D Green Breeze HAF Fan is specifically engineered for greenhouse environments, featuring a totally enclosed, dust-protected motor that handles high humidity. Its aluminum blades are designed to throw a wide, gentle air pattern rather than a harsh, direct blast that can dry out plants excessively. The rugged mounting bracket allows you to hang it easily from the high tunnel bows.
For effective circulation, place the fan high in the peak of the tunnel to push warm air downward, or set up a circular flow pattern if using multiple units. Wiring these fans requires access to a reliable power source, which may require running outdoor-rated extension cords or hiring an electrician. This fan is essential for any grower struggling with damp winter air and persistent mold issues.
Soil Thermometer – Taylor Dial Soil Thermometer
Air temperature only tells half the story; soil temperature dictates whether plant roots can actively absorb water and nutrients. Even if the air inside your high tunnel feels warm on a sunny February day, frozen or frigid soil will keep your crops dormant. Knowing the soil temperature helps you decide when it is safe to irrigate or transplant early spring starts.
The Taylor Dial Soil Thermometer features a rugged stainless steel stem and an easy-to-read dial face that does not require batteries. Its mechanical design is incredibly reliable in freezing conditions where digital screens often fail or lose power. The sharp probe easily penetrates compacted winter soils to give you an accurate reading at the root zone.
To get a true reading, insert the probe at least four to six inches deep into the soil and leave it in place for several minutes. Avoid pushing the probe into frozen crust, as this can bend the stem; use a pilot hole if necessary. This low-tech, high-utility tool is a must-have for every grower who wants to base their planting decisions on hard data rather than guesswork.
Drip Irrigation – Drip Depot High Tunnel Kit
Overhead watering in the winter is a recipe for crop failure, as wet leaves will freeze, rot, or succumb to disease. Drip irrigation delivers water directly to the soil surface, keeping the foliage dry and maintaining low humidity levels. Because plants drink very little in the winter, precise water delivery prevents waterlogging the soil.
The Drip Depot High Tunnel Kit comes complete with premium drip tape, pressure regulators, and tubing tailored specifically for protected cultivation. The kit uses pressure-compensating emitters to ensure even water distribution along the entire length of your beds. Its modular design makes it easy to customize for your specific bed layout and row lengths.
Before the first deep freeze, you must drain the system or blow out the lines to prevent freezing water from cracking the plastic fittings. Running the system on a gravity-fed setup can be tricky, as drip tape requires a minimum operating pressure to function correctly. This kit is ideal for growers who want a complete, easy-to-assemble watering solution that eliminates hand-watering chores.
- Tubing Size: 1/2-inch main line with 5/8-inch drip tape
- Operating Pressure: 10 to 15 PSI
- Emitters: Pre-spaced at 8 or 12 inches
Greens Harvester – Farmer’s Friend Quick Cut
Harvesting salad greens by hand with a knife is cold, slow work that can leave your fingers numb and ruin your harvest window. In the winter, you must harvest quickly during the warmest part of the day when the leaves are fully thawed. A mechanical harvester slashes harvest time from hours to minutes, keeping you warm and your greens fresh.
The Farmer’s Friend Quick Cut Greens Harvester uses a smooth, battery-powered reciprocating blade to cut a clean swath of greens in a single pass. A rotating macrame brush gently sweeps the cut leaves into an attached collection basket without bruising them. This tool achieves a clean, sharp cut that allows for rapid crop regrowth for subsequent cuts.
This harvester requires a learning curve to maintain a consistent cutting height, especially on uneven soil beds. It works best on densely seeded salad mixes, spinach, and baby brassicas rather than head lettuce or large kale. It is a significant investment that is best suited for growers selling to local markets or managing large winter beds.
Greenhouse Heater – Mr. Heater Big Buddy Propane Heater
While passive solar design does most of the work, extreme polar vortex events can push temperatures below what your double-layer system can handle. Having an emergency heat source ready to deploy can save an entire season’s worth of crops during a record-breaking freeze. You do not need to heat the tunnel constantly, just enough to keep the temperature above the killing point.
The Mr. Heater Big Buddy Propane Heater is a portable, indoor-safe radiant heater that delivers up to 18,000 BTUs of heat. It features a built-in low-oxygen safety shutoff and a tip-over switch, making it safe for use inside enclosed high tunnels. It runs on portable propane cylinders or can be connected to a larger propane tank with an optional hose.
Keep in mind that burning propane releases moisture into the air, which can temporarily spike humidity inside the tunnel. This heater is meant for emergency overnight use during extreme cold snaps rather than continuous, season-long heating. It is the perfect insurance policy for hobby farmers who cannot afford to lose their winter investment to an unexpected freeze.
Best Practices for Harvesting Frozen Winter Greens
One of the most critical rules of winter growing is to never touch or harvest greens while they are frozen. When temperatures drop below freezing, water inside the plant cells migrates to the spaces between the cells, causing the leaves to appear limp, dark, and glassy. If you handle them in this state, the ice crystals will puncture the cell walls, leaving you with a pile of black, mushy slime once they thaw.
Wait until the sun warms the high tunnel and the leaves naturally reabsorb their moisture, returning to a crisp, turgid state. This thaw window typically occurs between late morning and early afternoon on sunny days. Once harvested, dunk the greens in cold water to wash away any soil and help them retain their crispness before storage.
Maintaining Your High Tunnel Through the Spring Thaw
The transition from winter to spring brings rapid temperature fluctuations and heavy, wet snow that can threaten the structural integrity of your high tunnel. Regularly clearing heavy snow build-up from the sides of the tunnel prevents the plastic from stretching or collapsing under the weight. As the ground thaws, check your anchor posts and tension wires to ensure they have not shifted in the muddy soil.
Spring is also the time to transition your crops, clearing out the spent winter greens to make room for early warm-season plantings like tomatoes and cucumbers. Thoroughly clean your row covers and store them in rodent-proof bins to prevent damage over the summer. Taking care of your equipment now ensures your high tunnel is ready for another productive year of year-round growing.
Winter growing in a high tunnel turns the coldest months of the year into a season of abundance and joy. By equipping your structure with the right tools, you can protect your crops from harsh freezes and simplify your daily chores. With a little preparation and the proper gear, you will be harvesting fresh, sweet greens all winter long.
