What Happens when You Put a Plastic Bag over a Plant

Watering houseplants when you are away is always a problem. Even if you ask a friend or relative to water them for you, you’ll likely come home to find a plant or two either forgotten or overwatered. That’s unfortunate because there’s an incredibly easy way to water houseplants while you’re away, even if you’ll be gone for weeks or months!

What Happens when You Put a Plastic Bag over a Plant

Just water the plant normally before you leave, draining the water in the saucer as you go. Remove any dead or dying leaves or faded flowers: anything that might fall off and rot while you’re away (not that a little rotting plant tissue will do any harm per se, it’s just a matter of making your plant look better when you return home). Now place the plant in a clear plastic bag: a dry cleaning bag works well for larger plants. You can also put several plants together in one large bag. Then just close the bag with a twist-top and put the plant in a moderately lit place without direct sun. The last point is important: if you put a plant enclosed in plastic in a sunny place, it will literally cook!

In a plastic bag, your plant can survive for months without any water. This is because most of the water you normally give your plants is simply lost through transpiration and evaporation: in a sealed bag, the humidity is practically 100%. There is no transpiration or evaporation and therefore your plant will use almost no water.

I can just hear you saying: “Yes, but how will my plant breathe if it is sealed in a bag?” I can assure you that it will breathe perfectly. Remember, plants consume carbon dioxide and release oxygen during the day. Well, at night they do just the opposite. Yes, that’s right: plants provide all the “air” they need for their own survival. They are perfectly happy to be enclosed in a plastic bag.

How long can you keep your plants sealed like this? Easily 6 months, quite possibly up to a year. There are sealed terrariums that have not been opened in decades and the plants are still alive. Eventually, of course, your plant’s growth will be stunted because it will use some of the water and carbon dioxide to grow, but that will take months or even years. Even when it does, your plant will still be in good shape, it will just grow more slowly than usual.

Just think. One year of autonomy means you’ll have time to take a trip around the world! The really annoying thing, though, is that your plant will usually be in better shape when you get back than when you left it!

One caveat: Most dry-climate plants (cacti and succulents) won’t appreciate the high humidity in a plastic bag, but they’re even easier to care for while you’re gone. Just water them well, put them away from a sunny window (to slow their growth), and go on your travels. They will keep for at least 6 months, although they may look a little shriveled when you return.

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