As the gardening season progresses, one of the greatest challenges growers face is the unpredictable nature of the weather, particularly early frosts. These sudden dips in temperature can spell disaster for tender crops that are not yet ready to be harvested. While we cannot control the weather, we can certainly protect our plants from its harshness. One effective way to do this is by using row covers.
Row covers are an indispensable tool for gardeners, offering a versatile and practical solution to shield crops from early frosts, extend the growing season, and enhance overall plant health. In this guide, we’ll find out what row covers are, how they work, the types available, and how to use them effectively to protect your crops from early frosts.
What Are Row Covers?
Row covers are lightweight, fabric-like materials that are draped over rows of crops to protect them from the elements. These covers act as a barrier, creating a microclimate that can shield plants from frost, extreme temperatures, pests, and even wind damage. Row covers come in various materials and thicknesses, allowing gardeners to tailor their use to specific crops and growing conditions.
At their core, row covers serve to insulate plants from environmental stressors while still allowing light, air, and moisture to pass through. This delicate balance makes row covers an excellent tool for frost protection, especially during those unpredictable transition periods between seasons when temperatures can fluctuate dramatically.
How Row Covers Work to Protect Crops from Frost
The primary function of row covers in frost protection is to trap heat around the plants, effectively insulating them from the cold. Row covers work by creating a thin barrier between the cold air and the plants, helping to retain the heat that rises from the soil after sunset.
Even a slight elevation in temperature can make a significant difference, as row covers can keep the temperature beneath them 2 to 4 degrees Fahrenheit warmer than the outside air. This might not seem like much, but during an early frost, a few degrees can mean the difference between a healthy crop and one that’s damaged or destroyed by cold.
Key Benefits of Using Row Covers for Frost Protection:
- Trap Warmth: Row covers help retain the warmth that radiates from the soil, preventing frost from settling on plant leaves and stems.
- Maintain Moisture: While row covers allow moisture to pass through, they also help prevent plants from drying out by maintaining consistent humidity levels around the crops.
- Create a Barrier: The cover creates a physical barrier that protects crops from frost, wind, and even some pests, without restricting sunlight.
Types of Row Covers
Not all row covers are the same, and choosing the right type for frost protection depends on several factors, including the crops you are growing, the severity of the frost, and how long you expect to use the covers. Let’s take a closer look at the most common types of row covers available and their specific uses.
1. Floating Row Covers
Floating row covers are one of the most versatile and commonly used types of row covers. As the name suggests, these covers “float” directly on top of the crops without the need for support structures like hoops or stakes. They are made from lightweight, breathable fabric, such as spun polypropylene or polyester, which allows light, air, and water to penetrate while still offering protection from frost.
Advantages of Floating Row Covers:
- Ease of Use: Floating row covers are simple to install and can be placed directly on the crops, making them ideal for quick frost protection.
- Lightweight: The material is so light that it won’t damage delicate plants as they grow underneath.
- Flexibility: Floating row covers can be easily adjusted, removed, or repositioned, giving you flexibility as the growing season progresses.
Best Uses: Floating row covers are particularly effective for protecting tender crops like lettuce, spinach, young seedlings, and newly transplanted plants from light frost.
2. Supported Row Covers (Hoop Covers)
Supported row covers, also known as hoop covers, use frames or hoops to keep the cover elevated above the plants, creating a tunnel-like structure. These covers are ideal for protecting taller plants or crops that need a little extra breathing room. The support structure keeps the fabric from resting directly on the plants, reducing the risk of crushing delicate foliage.
Advantages of Supported Row Covers:
- No Contact with Plants: Since the fabric is supported by hoops, there’s no direct contact with the plants, which reduces the chance of damage.
- Air Circulation: Supported row covers allow for better air circulation around the plants, which helps prevent moisture buildup and reduces the risk of fungal diseases.
- Protection for Taller Crops: This type of cover works well for crops like broccoli, cabbage, and tomatoes, which need more vertical space.
Best Uses: Supported row covers are best suited for larger plants and crops that need protection from moderate frosts or sustained cold weather.
3. Heavier-Weight Frost Cloths
Heavier-weight frost cloths, also known as frost blankets or frost protection fabric, are made from thicker materials than traditional row covers. These cloths provide extra insulation, making them ideal for areas that experience heavy frosts or sudden temperature drops.
Advantages of Heavier-Weight Frost Cloths:
- More Insulation: The thicker material offers better frost protection, keeping the air underneath the cover significantly warmer.
- Durable: These covers are more durable than lightweight versions, making them suitable for repeated use throughout the season.
- Protection in Extreme Conditions: Heavier-weight frost cloths are designed for use in more extreme weather conditions, including hard frosts.
Best Uses: Use heavier-weight frost cloths to protect cold-sensitive crops like tomatoes, peppers, and squash when early frost threatens your garden.
4. Plastic Row Covers
Plastic row covers, typically made from clear polyethylene or polyvinyl, create a greenhouse-like effect by trapping heat and moisture inside. These covers are not breathable like fabric row covers, so they are often used in combination with ventilation systems to prevent plants from overheating during the day.
Advantages of Plastic Row Covers:
- Maximum Heat Retention: Plastic row covers provide excellent heat retention, making them suitable for regions with very cold temperatures.
- Moisture Protection: Plastic covers also provide a water-resistant barrier, protecting plants from excessive moisture during rain or snow.
Best Uses: Plastic row covers are ideal for extending the growing season into late fall or early spring, particularly for cold-hardy crops like kale, carrots, and beets.
How to Use Row Covers to Protect Against Early Frosts
Now that we’ve discussed the types of row covers available, let’s dive into the practical steps for using them to protect your crops from early frosts. The process involves careful planning, timely installation, and proper management of the covers to ensure your crops remain safe and healthy.
1. Monitor the Weather
The first step in frost protection is staying informed about upcoming weather conditions. While row covers are highly effective, they must be installed before the frost hits for maximum protection. Keep a close eye on the forecast, especially during transitional months when frost is more likely to occur.
- Be Proactive: Don’t wait for frost to arrive before acting. Install your row covers as soon as nighttime temperatures start to dip below 40°F (4°C).
- Watch for Frost Warnings: Pay attention to local frost warnings or advisories, which will give you a heads-up when frost is imminent.
2. Choose the Right Type of Row Cover
Selecting the appropriate row cover for your crops and climate is essential. Consider the following when choosing a row cover:
- Light Frost (32°F – 28°F / 0°C – -2°C): For light frost protection, a lightweight floating row cover should be sufficient. These covers will provide a few degrees of insulation and prevent frost from settling on your plants.
- Moderate Frost (28°F – 24°F / -2°C – -4°C): For more severe frost, opt for a supported row cover or a heavier-weight frost cloth. These covers offer greater protection and will keep plants warmer during colder nights.
- Severe Frost (Below 24°F / -4°C): If you are expecting severe frosts, a combination of supported row covers and plastic sheeting may be necessary. Plastic row covers provide the most insulation, but they must be carefully managed to prevent overheating during the day.
3. Prepare Your Plants and Soil
Before placing your row covers, make sure your plants and soil are prepared to get the maximum benefit from the protection.
- Water Your Plants: Moist soil retains heat better than dry soil, so give your plants a thorough watering before installing row covers. The water in the soil will slowly release heat during the night, helping to protect your crops from frost.
- Remove Weeds and Debris: Clear any weeds or plant debris from the area before installing the row covers. Weeds can harbor pests, while debris can prevent proper air circulation around your plants.
- Mulch for Extra Protection: If you’re particularly concerned about frost damage, adding a layer of mulch around your plants can provide additional insulation. Organic mulch, such as straw or leaves, will help trap warmth in the soil.
4. Install the Row Covers
Once the weather forecast indicates that frost is approaching, it’s time to install your row covers. Follow these steps to ensure your plants are adequately protected:
- Drape the Cover Over the Plants: If you’re using a floating row cover, simply drape the material directly over your crops, making sure it covers the entire row and touches the ground. For supported covers, place the hoops or stakes over the plants and stretch the cover over them, securing it to the ground.
- Anchor the Edges: Secure the edges of the row cover by weighing them down with rocks, soil, or landscape staples. Make sure there are no gaps where cold air can seep in, especially around the edges.
- Leave Room for Growth: If your plants are still growing, leave a little slack in the row cover to accommodate their growth. For supported row covers, ensure that the hoops are tall enough to allow the plants to mature without being restricted.