Can plants breathe under a cloche?

Yes, plants can technically breathe (respire) under a cloche, but ensuring adequate ventilation is crucial to prevent conditions that can hinder their vital gas exchange processes and potentially damage the plant.

Plants "breathe" through tiny pores called stomata, primarily located on the underside of their leaves. This process involves:

• Photosynthesis: During daylight hours, plants take in carbon dioxide (CO2) and release oxygen (O2) to create energy from sunlight.
• Respiration: Plants continuously take in oxygen (O2) and release carbon dioxide (CO2) to convert stored sugars into usable energy, a process that occurs both day and night.

The Role of Cloches in Plant Health

Cloches, often made of glass or plastic, are widely used in gardening to create a protective microclimate for plants. Their primary benefits include:

• Temperature Regulation: They trap warmth, extending the growing season and protecting plants from frost.
• Pest and Disease Protection: They act as a physical barrier against pests and certain environmental stressors.
• Humidity Control: They help maintain higher humidity levels around the plant, which can be beneficial for some species.

Challenges for Plant Breathing Under Cloches

While beneficial, cloches, especially traditional bell cloches made of plastic or glass, can create an enclosed environment that poses significant challenges for plant breathing and overall health if not managed correctly.

• Overheating: One of the most significant risks is overheating. Trapped sunlight can rapidly raise temperatures inside the cloche, far exceeding ideal conditions for the plant. High temperatures can stress plants, denature enzymes critical for photosynthesis and respiration, and lead to wilting or even death. Such heat can severely "damage plants."
• Insufficient Gas Exchange: A lack of proper ventilation prevents the free movement of gases.
  • CO2 Depletion: During active photosynthesis, the limited supply of CO2 within an unventilated cloche can quickly become depleted, slowing down or stopping food production.
  • Oxygen Accumulation/Depletion: While oxygen is released during photosynthesis, it can accumulate to very high levels, potentially inhibiting plant processes, or conversely, be depleted if respiration rates are very high in the absence of light.
  • Stifled Respiration: Without fresh air, the plant's ability to efficiently take in oxygen for respiration and release CO2 can be compromised, effectively "stifling" its chance to breathe properly.
• Excessive Humidity: While some humidity is good, very high levels trapped under a cloche can reduce transpiration (the plant's way of moving water and nutrients) and create a breeding ground for fungal diseases like powdery mildew, which further stress the plant.

Ensuring Optimal Plant Breathing and Health Under a Cloche

To leverage the benefits of cloches while preventing harm, proactive management is essential.

• Ventilation is Key: Regular ventilation is the most important step. This involves:
  • Periodic Removal: Removing your cloche periodically to allow for a complete exchange of air and to give plants a chance to breathe fresh air.
  • Propping Up: Propping up your cloche to create gaps for air circulation without fully exposing the plant. This is particularly useful on warmer days or when the sun is strong.
  • Vented Cloches: Consider using cloches designed with built-in adjustable vents.
• Monitor Plant Health: "Make sure to carefully monitor plant health." Regularly check for signs of stress, such as wilting, yellowing leaves, or fungal growth. Adjust ventilation based on weather conditions and plant response.
• Strategic Placement: Place cloches where they receive appropriate sunlight, avoiding areas where they might accumulate too much heat.
• Watering: Water plants appropriately; avoid overwatering, as the cloche will reduce evaporation.

Cloches and Plant Breathing Considerations

Here’s a summary of considerations when using cloches for plant health:

By understanding the delicate balance of a cloche's microclimate and implementing proper ventilation techniques, gardeners can effectively use these tools to support healthy plant growth and ensure plants can "breathe" without hindrance.