How Big Should Your Pot Be for Your Phalaenopsis?

Pot Size

• Typically, moth orchids are sold when they are no longer young seedlings and are of a mature age to produce flowers. The varying habit and natural size or form of moth orchid hybrids determines what size container they are grown in. At the nursery, moth orchids are grown and sold in plastic containers that are either 4, 5 or 6 inches in diameter. Older and larger plants with more leaves and roots grow in larger pots. The orchids can be maintained in the same size pots for a couple of years, only using a container 1 inch larger in diameter at the next re-potting. The pot needs to be large enough to prevent the plant from toppling when set on a level surface.

When to Repot

• A moth orchid needs re-potting every one to three years, mainly because of degradation of the potting medium. If you choose to re-pot, do it immediately after the flowering wanes in spring. This reduces the stress on the orchid plant as it has many months over the rest of spring, summer and early fall to re-establish its roots and grow well in the warmth and light. You don't need to re-pot every year; slight overrunning of moth orchid roots over the edges of the pots doesn't necessarily mean the orchid is unhealthy or requires immediate re-potting.

Pot Size and Growing Medium

• Moth orchids are not earth-dwelling plants. Rather, they naturally clasp their roots onto the trunk or branches of other plants. When grown in pots, the orchids grow in a porous material that allows water and air to freely flush through and around the medium and plant roots. Tree bark nuggets, pulverized peat or inorganic materials such as pumice, Styrofoam packing peanuts or expanded clay pellets are used. Potting soil is never used. Peat-based media and smaller-sized bark nuggets decompose relatively quickly, so re-potting is needed annually to provide better aeration for orchid roots. Therefore, the same size container may be used in re-potting.

Stabilizing Orchid Containers

• Traditionally, terracotta clay pots were used for orchid growing, but through the years, horticulturists realized that salt build-up from water accumulates in the porous terracotta materials. The porous material also makes removing clasping moth orchid roots challenging. The pores also created a habitat for diseases. Often, a clay pot needed to be smashed to get the orchid out of the container. Today, growers use plastic or vinyl pots, which are lightweight and inexpensive. To prevent them from tipping over with a moth orchid in them, you can temporarily place the plastic pot inside a larger, clean terracotta pot. This heavy clay pot acts like a weighted sleeve.