Contrary to what many people believe, Venus flytraps adjust very well to low levels of humidity. Many people successfully grow venus fly traps in desert-like conditions and the plants thrive. However, the higher you keep the humidity, the better off the plant will be.
If you can keep the humidity in the 50%-70% range, that is perfect for Venus flytraps. However, I have successfully grown healthy flytraps with an average humidity of less than 30%. If you live in an extremely hot and arid climate where the humidity is regularly below 10%, there are a few things you can do to raise the ambient humidity near your Venus flytraps.
1) Use a terrarium – An old aquarium works well. If you keep it outside during the heat of the day, remember not to leave a top on it. Doing so might cook your plants. If you only have one plant, you can also use a 2-liter bottle with the bottom cut out of it and place it over the top of the plant. You might need to trim the hole on the top as well to allow more air to circulate in so the plant doesn’t cook.
2) Keep them near standing water – The tray method works well to raise the humidity around the plant.
3) Keep their soil moist on top – Keeping the soil moist will also help raise the humidity near the surface of the soil for the plant.