Orchids - Repotting Basics

Orchids look exotic but have the same structure as more familiar houseplants. They have roots, stems, leaves and flowers; it is just that these parts are adapted a little differently in an orchid. Most plants in your yard or home are anchored to the ground by their central root system, which expands out into finer and finer roots that grow down into the soil to absorb water and nutrients. Orchids, on the other hand, use their roots to attach themselves to trees or rocks, positioning themselves to take advantage of the light in their native habitat. The central core of the root is where the moisture and nutrients are absorbed. Covering the core is a spongy material, called velamen, which stores the water for the plant. The velamen needs to have a balance of air and moisture to keep the plant growing happily. This is why an open potting media with good drainage is critical. If the velamen stays too wet, the core rots and the orchid is unable to utilize water and nutrients. Open potting medium allows drainage and airflow to the velamen, yet holds enough moisture to support the needs of your orchid.

What is the best potting material? - A fresh, well drained but water-retentive medium is critical to sustain a healthy root system to keep your orchid growing and blooming. Select the option best suited to your plant and gardening style. There are three main types of potting material:

  • Bark-based mix - this retains moisture well and is forgiving of watering errors. The downside is that the bark breaks down quickly requiring more frequent repotting.
  • Peat-based mix - retains moisture well, needs frequent watering and re-potting.
  • Inorganic, hydroponic method used by experienced orchid enthusiasts in a variety of media with success.

When should I repot? - A good rule of thumb to use when deciding to repot an orchid is to pot for the bottom, or roots, of the plant, not for the top, or foliage. Focus on the roots to keep your orchid vibrant. An orchid needs repotting for the following reasons:

  • The potting mix breaks down and is no longer able to sustain moisture in a healthy way. The symptom would be that the roots start to die because the velamen is unable to store water properly. The solution would be to simply replace the potting mix with fresh potting mix. A larger pot may not be required.
  • The plant has outgrown the container. The symptom would be that the roots would be growing out of the container. The solution would be to divide the plant and pot it in two pots similar in size to what it was in OR to repot the plant into a larger pot.

For more information about caring for this beautiful plant, contact the American Orchid Society (www.aos.org/)

To watch two excellent videos before you try repotting yourself, go to the above website, click on "Video Library" in the left-hand sidebar and select "Repotting a Healthy Orchid" (5:33 minutes) or "When to Repot?" (8:27 minutes).

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