Misting an orchid is a common practice used by many plant owners hoping to replicate the high humidity of the orchid’s natural habitat. While the intention to provide a tropical environment is correct, the practice is generally discouraged for most hobbyists. Orchids thrive in relative humidity levels ranging between 40% and 70%. Misting cannot reliably or safely maintain this necessary condition, highlighting the need for long-term solutions.
The Problem with Misting
Misting is largely ineffective because the water droplets evaporate almost instantaneously, providing only a fleeting increase in moisture that lasts mere minutes. The volume of water released by a hand-held sprayer is too small to significantly change the humidity level of the growing area. This temporary boost does not reduce the orchid’s overall water loss through transpiration.
The more concerning issue with misting is the potential for disease when water is allowed to sit on the plant’s surfaces. Water droplets that pool in crevices, such as the crown (the center where new leaves emerge) of a Phalaenopsis orchid, create ideal conditions for bacterial and fungal growth. These pathogens thrive in stagnant, moist environments and can lead to crown rot, which can quickly kill the plant.
The risk of rot is especially high if misting occurs in the evening, as the water will not evaporate quickly overnight due to cooler temperatures and reduced airflow. Bacterial infections, often spread by splashing water, can rapidly cause soft, foul-smelling spots that destroy plant tissue. Misting with cold water can also cause temperature shock to sensitive plant tissues.
Why Orchids Need Humidity
Orchids are predominantly epiphytes, meaning they naturally grow on other plants rather than in soil. In their native tropical and subtropical environments, these plants are constantly bathed in warm, moisture-laden air. This high ambient moisture is absorbed through the plant’s specialized root structure, the velamen, which quickly takes up moisture and protects the root’s inner layers from desiccation.
Low humidity levels, particularly below 40%, cause the orchid to lose water faster than its roots can take it up. This imbalance leads to visible signs of dehydration and stress. For instance, orchids with pseudobulbs will shrivel and wrinkle as the plant draws on its reserves.
Low moisture also directly impacts flower development, leading to a condition called bud blast, where developing flower buds dry out and drop off before they can open. Leaves may also develop dry, crispy edges. Maintaining a relative humidity range of 40% to 70% is necessary to slow down transpiration and keep the plant healthy.
Long-Term Solutions for Increasing Ambient Moisture
Since misting is a short-lived and potentially harmful practice, long-term methods are necessary to meet an orchid’s humidity needs. The most effective way to provide uniform moisture is by using a room humidifier. A humidifier releases a continuous stream of water vapor into the air, which can maintain a consistent, measurable humidity level across the entire growing area.
Using Humidity Trays
Humidity trays provide a localized increase in moisture directly beneath the plant. To construct a tray, a shallow container is filled with pebbles or gravel, and water is added until it reaches just below the top surface of the stones. It is important to ensure the orchid pot is elevated, resting on the pebbles, and not sitting directly in the water. Sitting in water would cause the potting medium to wick up excessive moisture and lead to root rot.
Creating Microclimates
Grouping plants together is a simple, effective technique that creates a beneficial microclimate. Plants naturally release moisture through transpiration from their leaves and evaporation from their potting medium. Placing them close to one another traps this moisture, raising the local relative humidity. Placing orchids in rooms with naturally higher moisture, such as a bathroom or kitchen, can also take advantage of the ambient conditions.