Polka dot plants will wilt if exposed suddenly to dry air. Photo: nbolmer, houzz.com
Question: I was taking cuttings of a polka dot plant and covered it with a clear plastic bag because this was the only way it seemed to work for me. If I didn’t use a bag, the plant died. However, now when I try and remove the bag, the leaves of the plant shrivel and droop. Any ideas for what I can do?
Answer: Yes, the polka dot plant (Hypoestes phyllostachya) is a delicate plant and has a hard time tolerating dry air.
Another plant in the same category is its cousin, the nerve plant (Fittonia albivenis, formerly F. argyroneura and F. verschaffeltii).
Both need high atmospheric humidity in order to root, which is why you’d had success starting it inside a plastic bag. That creates “greenhouse conditions” where the humidity can be close to 100%.
The secret to getting your now rooted polka dot plant to survive outside of the bag is to acclimatize it gradually to normal air humidity. One you’re sure it has rooted (you’ll be able to tell, because new leaves will start to appear), open the bag just a crack for a few days, then wider for a few days, then start pulling it down gradually, each time giving the plant a few days to adapt to the drier outside air. Eventually, your plant will be fully exposed and ready to face the drier air around it.
This technique is valuable too for most plants rooted under greenhouse conditions (high humidity). It’s always best to expose them gradually to outside air.
Remember, too, to water your polka dot plant regularly, keeping it at least slightly moist at all times. It doesn’t like dry soil either!
That said, depending on how dry the air in your home is, you may need to rebag or place your polka dot plant in a terrarium for the winter. The winter air in many residences is extremely dry, literally “desert dry”, often with less than 15% relative humidity (that in the Sahara Desert is usually about 25%).
Polka dot plants, nerve plants and other thin-leaved houseplants won’t be able to tolerate that. They need at least 50% humidity at all times and really prefer 70% humidity. A spot inside a clear plastic bag, under a transparent dome or in a terrarium may be the only places they’ll be able to survive the winter heating season.
If you try this, remember you’ll again have to acclimatize them, gradually, to outside conditions every spring when you remove their protective covering.