Underwatered Orchids: The plague of the forgetful orchid grower

   For those of you who frequently forget to water your orchids, you’re not alone.  For a long time, my orchids only got watered when I remembered to water them.  Actually, part of the reason I love orchids is that they don’t have to be watered as often as some of the other typical houseplants.  They can handle my forgetfulness and neglect.
   Last month, I abandoned my orchids for a trip Yosemite National Park and a biotechnology conference.  Before I left, I watered my orchids very well, but, after that, they were on their own for 2.5 weeks.  None died, thankfully, but I do have some nice examples of what happens when you don’t water your orchids enough. 

How much should you water your orchids?
That’s not an easy question to answer because it depends on a lot of factors:

1. Plant species- some orchids require more water, some don’t.  You have to find out what your plants prefer.
2. Pot size- smaller pots hold less water and the plants tend to dry out sooner than orchids in larger pots.
3. Planting media- different media mixes hold water differently.  Larger pieces (bark, stones, perlite) hold less water and will dry out faster than smaller pieces.  Moss (usually used for Phalaenopsis orchids) holds water very well (like a sponge).
4. Growth phase- orchids that are actively flowering generally require more water than orchids that are only growing.  Conversely, orchids in their rest phase (neither flowering or actively growing) use less water.
5. Light and Temperature- orchids in higher light and higher temperatures will use water faster than orchids in cooler, darker conditions

How can you tell when a plant needs water?
After overwatering and killing a bunch of Phalaenopsis, my new rule of thumb is to stick a finger in the media.  If the media is still damp, don’t water the plant. 

• Major signs of overwatering are rotted roots (coming up in the next blog post) or crown rot in Phalaenopsis. 
  

Major signs of underwatering orchids:
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1. Dried out pseudobulbs.
​ In sympodial orchids, the pseudobulbs are used to store sugar and water.  When the pseudobulbs are young and healthy, they are plump and filled.  When the plants are underwatered they draw from their water storage, causing the pseudobulbs to wrinkle.  Once a pseudobulb wrinkles, it doesn’t unwrinkled.

*Note: these are two different Oncidium plants.

2. Horizontal pleated leaves (wrinkles that go across the width of growing leaves)
   Underwatered plants can develop horizontal crimping or pleating on newly developing shoots.   If the newly growing leaf doesn’t get enough water while it’s developing, it forms these horizontal pleats (pictured below in the Oncidiums I abandoned).  These don’t go away as the plant ages.  As far as I can tell, this doesn’t hurt plant growth, although it probably doesn’t go over well with judges if you submit your plans in flower shows.

***Note: some orchids, like the Zygonisia pictured on the right, have naturally pleated leaves.  These pleats run along the length of the leaf (opposite of pleats caused by underwatering).  

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