Monday, March 4, 2013

The proper care and feeding...

As a continuation of prior posts describing carnivorous plants, the following is for anyone interested in growing them, because if you've ever bought a Venus flytrap you've probably also watched it die. Even though they're often sold with houseplants, they have different requirements. But if you want to try it (again?) here's some general tips based on my experiences and what I learned from books and others:

  • Water – Carnivorous plants (CPs) are native to wet, boggy areas, so they prefer to be much wetter than regular houseplants. Sarracenia (American pitcher plants) and sundews should even be left standing in water frequently. But tap water will probably have too much dissolved solids (aka "hard water") and added chemicals such as chlorine which will kill the plants. (Water softeners that add salt to the water will kill your plant even faster!) Instead, buy distilled or RO (reverse osmosis) water from the store (be careful not to get "mineral" or "drinking" water). Or you can collect rain water as long as it's not too dirty or oily.
  • Light – Sarracenia, most Drosera, and flytraps do best with full sun. Nepenthes and most Pinguicula will prefer some shading. My plants did better outside (in spite of the low humidity - see below) where they usually got several hours of direct sunshine. A bright windowsill will also work, but be aware that temperatures can get high when the sun is shining on your plants.

  • Humidity – Most CPs grow in humid environments which makes it a little harder here in dry Western deserts. While I did what I could to keep the humidity around the plants higher (like keeping them out of breezy areas), Sarracenia, flytraps, and some sundews seemed to manage in spite of it. Nepenthes (tropical pitcher plants) however, need high humidity and won't form pitchers without it so you'll need something like a greenhouse or a terrarium with lights.
  • Soil – Carnivorous plants are native to poor soils, so regular potting soil won't do. Long-fiber sphagnum moss (not green or sheet moss) is probably the best and may even start growing, but peat moss mixed with white silica sand (the kind used for sandblasting) at a ratio of 1:1 or 2:1 peat/sand works well (Perlite can be substituted for the sand). The aim is to have a low-nutrient but highly water-retentive soil. If you want to try a Cobra Lily only use sphagnum.

  • Pots – Plastic pots with drainage holes are the best because they don't dry out as fast as clay pots or leach salts. Put them in extra-deep water saucers to keep the soil wetter. You can also grow several plants together in one large pot.
  • Feeding – CPs usually catch plenty of bugs on their own, especially when grown outside. You can give them the occasional bug, but don’t overdo it. And never feed them anything like hamburger! Fertilizers aren't needed and would likely be fatal to the plants.

  • Dormancy – Temperate (non-tropical) plants like Sarracenia, flytraps, and many sundews need a "rest period" each year, similar to trees stopping growth during winter. If they don't get it they'll eventually die. Sometimes just moving them to a cool and shady spot (or maybe a garage) during winter works. I found it difficult to keep plants dormant for long inside the house and the Sarracenia usually started flowering by the end of January, but it seemed to be enough.

If you have questions feel free to ask. And some time I'll review some books about CPs.

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