Orchids are popular houseplants, often admired for their beautiful and long-lasting flowers. While they are resilient, their survival and re-blooming ability hinge almost entirely on receiving the correct amount of water. Unlike most common potted plants, orchids possess a unique physiology that demands a different approach to hydration. This guide will clarify the specific needs of potted orchids and demystify the process of keeping them properly watered.
Why Orchid Watering Is Unique
The majority of orchids grown as houseplants, such as the common Phalaenopsis or “moth orchid,” are epiphytes in their native tropical environments, meaning they naturally grow on trees rather than in soil. This aerial habitat led to the evolution of roots covered in a spongy, multi-layered tissue called velamen. The velamen acts like a sheath, rapidly absorbing water and nutrients during rain events.
The velamen’s function is to absorb moisture quickly and then dry out promptly to prevent rot. This biological adaptation means orchid roots are designed for high aeration and a fast wet-to-dry cycle, not for prolonged saturation. When potted in traditional soil or kept constantly damp, the roots are deprived of the necessary air pockets, leading to suffocation and root rot. The specialized potting media, typically consisting of bark chips or sphagnum moss, is designed to mimic this naturally airy, fast-draining environment.
The Proper Method for Watering Potted Orchids
Two primary methods are effective for delivering the thorough watering that orchids require: soaking and flushing. The soaking method involves placing the orchid, still in its inner plastic pot, into a container or sink partially filled with room-temperature water. Allowing the pot to sit in the water for 15 to 30 minutes gives the velamen and the potting medium ample time to fully rehydrate.
This immersion technique is particularly beneficial for bark-based media, which can initially resist water penetration. Once the soaking period is complete, lift the pot and allow all excess water to drain completely from the bottom holes. The flushing method involves running a large volume of water directly through the potting medium for several minutes.
Flushing ensures that water reaches all the roots and helps wash away any accumulated mineral salts from fertilizers or tap water. If using a decorative outer pot, ensure that no standing water remains in the saucer or cachepot after either method, as this will quickly lead to saturated roots and decay. The goal is to fully saturate the roots and media while ensuring they can begin the drying process almost immediately afterward.
Reading the Signs: When to Water
The timing of watering should never be based on a fixed schedule, but rather on direct observation of the plant and its environment. The most reliable visual cue is the color of the roots visible through the clear plastic nursery pot. Healthy, hydrated orchid roots will appear plump and bright green.
When the velamen is dry, the roots will change color to a silvery-gray or white, signaling that it is time to water. Another excellent indicator is the weight of the pot; a fully hydrated pot will feel noticeably heavier than one that is completely dry. Lifting the pot after watering and again a few days later helps a grower learn the difference between “wet weight” and “dry weight.”
For orchids potted in sphagnum moss, which retains moisture far longer than bark, the “finger test” is helpful. Gently inserting a finger about an inch or two into the moss will reveal if the center is still moist, indicating that watering should be delayed. Waiting until the moss feels nearly dry to the touch prevents overwatering.
Water Quality and Environmental Factors
The type of water used can affect an orchid’s long-term health due to mineral accumulation. Rainwater is ideal because it is naturally low in dissolved solids and free of chemicals like chlorine. Distilled or reverse osmosis water also provides a clean slate, but since these are devoid of minerals, a consistent feeding schedule is necessary.
If using municipal tap water, which often contains chlorine and various salts, let it sit out in an open container for 24 hours to allow chlorine gas to dissipate. High mineral content can lead to a buildup of salts in the potting medium, which can eventually burn the delicate root tips. Most orchids prefer a slightly acidic to neutral pH in the range of 5.5 to 6.5, which can be affected by hard, alkaline tap water.
Environmental conditions in the home significantly influence how quickly the potting media dries out. High ambient temperatures and strong air movement, such as from a fan, increase the rate of evaporation and necessitate more frequent watering. Conversely, a location with high humidity and cooler temperatures slows the drying process, meaning the time between watering sessions must be extended.