Repotting is one of the key ingredients to successful orchid growing. For most beginners who have never repotted an orchid, this task could be exciting, overwhelming or even down-right stressful.  On the other hand, the seasoned growers can find repotting to be a dreadful chore if they have go through several hundred plants every year.  We hope that our Repotting Series guides will help you become a better orchid grower.

If you have not read our first guide of this series, Repotting Series I - When to Repot an Orchid, we recommend that you take a moment to do so and get a better understanding on when it is most appropriate to repot your orchid.

Which Orchid Media Formulation to Use?

Below are guidelines that you can follow in selecting and preparing your orchid growing media or mix.  If you decide to follow one of our recommended orchid mix formulations, we suggest that you experiment on a few strong plants for at least a year before changing the orchid mix for your entire collection.

1) Type of Orchids.  Knowing the growth habits and cultural requirements of your orchids is imperative to picking the right media. If there is a lack of cultural information on an orchid, experiment with a few plants on different types of growing media until you find out through careful observation on what is best for your orchids.

General Guidelines:

• Standard Cattleya and Laelia - Medium (1/4"-1/2") to Large-sized bark (1/2" or larger), can be used alone or mixed with a combination of varying ratios of large-sized charcoal, coconut husk chips (CHC), volcanic rock, diatomite or expanded clay pebbles.
  

• Compact or Mini-Cattleya and Laelia - Medium-sized bark (1/4"-1/2"), can be used alone or mixed with a combination of varying ratios of medium-sized charcoal, coconut husk chips, volcanic rock, diatomite or expanded clay pebbles.  These orchids can also be mounted on cork bark slabs or manzanita wood sticks.

• Paphiopedilum  and Phragmipedium - Small (1/8"-1/4") to medium-sized bark (1/4"-1/2") mixed with a combination of varying ratios of small-sized charcoal, coconut husk chips, rockwool, perlite, sphagnum moss, peat moss, volcanic rock, diatomite or expanded clay pebbles.

• Phalaenopsis - The predominant medium used for growing Phals is 100% sphagnum moss. Even though the long-fiber, New Zealand sphagnum moss may be more expensive than the Chilean spaghnum moss, our experience with NZ moss confirms that it is superior in quality and cheaper in the long run.

• Cymbidium , Dendrobium , Catasetum , Cycnoches , Oncidium, Brassia - Small (1/8"-1/4") to medium-sized bark (1/4"-1/2") mixed with a combination of varying ratios of small-sized charcoal, coconut husk chips, rockwool, perlite, sphagnum moss, peat moss, volcanic rock, diatomite or expanded clay pebbles.

• Vanda and other vandaceous orchids - The predominant medium used in Thailand is charcoal but more and more of them are grown without media on wood, teak or plastic net baskets.

        If your orchid does not belong in any of the orchid genera described above, use this simple rule:

• Small or thin-rooted orchids - Small (1/8"-1/4") to medium-sized bark (1/4"-1/2") mixed with a combination of varying ratios of small-sized charcoal, coconut husk chips, rockwool, perlite, sphagnum moss, peat moss, volcanic rock, diatomite or expanded clay pebbles. Use the recommended formulas for Cymbidium, Dendrobium, etc.
  

• Large-rooted orchids - Medium (1/4"-1/2") to large-sized bark (1/2" or larger), can be used alone or mixed with a combination of varying ratios of large-sized charcoal, coconut husk chips, volcanic rock, diatomite or expanded clay pebbles.  Use the recommended formulas for Standard Cattleya and Laelias.
  

• Small to medium-sized orchid seedlings - Small bark (1/8"-1/4") mixed with a combination of varying ratios of small-sized charcoal, coconut husk chips, rockwool, perlite, sphagnum moss, peat moss, volcanic rock, diatomite or expanded clay pebbles.  Use the recommended formulas for Paphiopedilum and Phragmipedium.

If you do not have the time or patience to make your own mix, you can readily purchase them in the Orchid Mix & Media section of our eBay store.

2) Type of Growing Environment. Knowing where you plan to grow your orchids, indoors or outdoors, in a greenhouse or shade house, is an important consideration in choosing the correct type of orchid media or mix.  For example, if you grow in an outdoor, open-air environment, choose an orchid media like coconut husk chips and volcanic rock that retains more moisture than other media.

If you grow your orchids in a greenhouse environment where high humidity can be maintained, you should choose an orchid mix with perlite or charcoal so that the media will dry out quicker. Growing indoors under HID lights and artifical ventilation will require you to use a balanced mix of moisture retentive media like sphagnum moss, volcanic rock with fast-drying materials such as perlite and charcoal.

3) Watering regimen. If you have a tendency to over-water your orchids, it is better to use an orchid medium that is more porous such as volcanic rock, diatomite or expanded clay pebbles, so it can quickly dry out in a few days.  If you can only water your orchids on weekends, then use an orchid mix that retains water for a longer period of time such as sphagnum moss, coconut husk chips or peat moss.

4) Type of Pot Used. Pots can be made of clay, plastic , wood or glass so each one can have a different drying effect on the orchid media that you use. If you have tall pots, use an orchid mix that will dry out a little faster so the bottom of the pot does not get too soggy. Orchid media will dry out quicker in clay pots or plastic pots with large or numerous drainage holes so you should consider those mixes that are more moisture-retentive such as coconut husk chips, volcanic rock, diatomite and sphagnum moss.

Let us know if this guide was helpful and if you have any suggestions to help us improve it for everyone's benefit.

Disclaimer: We are not responsible for the loss or damage to your plants and do not warrant or guarantee the effectiveness of the above items as we cannot control all the other factors involved in caring for your orchids. As a safety and health precaution, we also recommend that you wear a particulate respirator (mask) and eye goggles when handling any type of orchid media.