Laidback Gardener Tip of the Day

No Diapers for Houseplants!

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There is a video circulating these days (How Can Diapers Help Your Plants Grow?) that several people have sent me. It suggests that you can cut open a disposable diaper, retrieve the absorbent crystals inside and add these crystals (hydrogels) to the potting mix of your houseplants. And it seems to make sense: after all, hydrogels are said to absorb 500 times their weight in water. Thus, the crystals ought to absorb water and release it slowly, keeping your plants moist longer. The video claims it cuts your watering needs in half… and who doesn’t want great results with less effort? Plus the video seems very professional, the narrator is compelling and enthusiastic, the video seems to show you exactly what to do… so far, so good! But there’s a catch: it simply doesn’t work!

You should know hydrogels absorb water very well, but are not so good at releasing it. After all, disposable diapers are designed to absorb liquids but not with the idea that you’ll then expect them to dry out for future use. Thus, a plant treated with these crystals will have approximately the same watering needs as a plant growing in a more traditional growing mix. This is confirmed by test after test: there is little to no difference in the frequency of watering when you compare ordinary potting soils and the same soils with added hydrogel crystals. In fact, in some tests, the plants growing in hydrogel mixes dried out more quickly than those without the mix. (The difference was minor, but still!)

I tried a very small-scale experiment with hydrogels about 20 years old, when hydrogels first came on the market. Only two plants, so it wasn’t a thorough test. Still, I saw no difference in either the amount of water needed for the two plants nor any difference at all in frequency. I haven’t used hydrogels since!

Of course, that may be a mistake. There are modern hydrogels designed for horticultural use that are likely better for plant culture then chopped up diapers. Even so, though, if you read scientific reports on the subject, the results are not very conclusive. It would appear hydrogels work (a bit) under some circumstances and not at all in others.They seem to operate best when used in the ground (and not so well in pots) using very drought sensitive plants. Plus there are questions about what happens to them when they degrade (they don’t last forever).

My conclusion? Keep diapers for baby and use normal potting soil for your houseplants…

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Colored hydrogel crystals at a trade show: they’re being used here for houseplant cuttings.

But what a minute! Just because crystals harvested from diapers are essentially useless as a watering agent for container plants doesn’t mean they have no useful functions. In the video, you’re shown how to use hydrogels to keep cut flowers moist and that will work. Not mentioned is the fact you can root cuttings in them as well, although eventually you’ll have to move them to real soil. And you can color hydrogel crystals as per the video with food dyes, turning them color of your choice. You’ve probably seen hydrogels, often in the form of gelatinous beads, used this way in plant shows and county fairs, but crystals extracted from diapers will give a similar result.

There are a few other inconsistencies in the video; you see plants potted into containers with no drainage holes (not very good horticulture!), a strange tip about mixing seeds with a hydrogel/potting mix blend (you’d get the same results in potting mix alone… and what a waste of seeds too!), and a few others.

The most surreal point in the video is when it recommends not adding food coloring to the crystals in potting soil so “your plants won’t turn funny colors as they grow”. Well, actually, you can pour all the food coloring you want into soil with or without hydrogels and the dye simply won’t change the plant’s color. Plant roots cannot absorb food coloring directly, they must wait until it is broken down into simpler molecules, and by that stage, the color has been lost. So your plant will keep its original color regardless of any color added.

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Cut flower carnations soaking in colored water will change color.

That said, you can do a neat little experiment by coloring flowers, not plants. If you put cut flowers in hydrogel or water stained with food coloring, the flower will take up the food color. That’s because the colored water passes directly into the flower stalk where vascular tissues carry it to the flower’s petals: there are no roots to act as filters. This phenomenon is observed more easily with white flowers, as they have no pigments to mask the dye. This technique is widely used in the floral industry: you’ll find plenty of dyed flowers in almost any florist shop.

So, a fun video to watch and very thought-provoking, but somebody forgot to do their homework!

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

10 comments on “No Diapers for Houseplants!

  1. Pingback: Garden Myth: Irrigating Plants with Disposable Diapers | Laidback Gardener

  2. Would it work if the diaper crystals were put at the bottom of a pot that has no drainage holes? Then top with potting soil and the pant.

    • I fail to see what that would change. At first, the hydrogels would probably hurt the plants by stealing water from their roots, then, once they were saturated and no longer effective, the roots would end up soaking in water as they do in any pot with no drainage hole. There is no easy solution for gardening in pots without drainage holes. and certainly not a “drainage layer”. Pots are really only effective once you drill holes into them.

  3. I’ve seen a time lapse video about seedling with hydrogel. In terms of irrigation, was it “fake” too?

    • Not necessarily. Hydrogels used in just the right circumstances can be effective, but they’re not a perfect tool.

    • I’ve used hydrogel beads from disposable diapers mixed into the soil of potted houseplants and it has worked wonders on my plants. Although the beads stee not MEANT to release moisture, if a plant is dry it will draw the moisture out of the beads. (No need for the beads to “release” the moisture). I have to disagree that it doesn’t work, because I’ve went from having to water my plants weekly to watering them biweekly, and my plants are growing st a faster rate.

  4. Canadian Dave

    I can understand the “inconclusive” results if you’re only using it for a reduced watering schedule, but I think the other gains of using the hydrogel crystals should be mentioned as well…

    Firstly: As the crystals absorb and release water, they swell and then contract in size, naturally aerating the soil…

    Secondly: If you were to overwater a pot of normal soil without proper drainage, you could run the risk of root rot… even with proper drainage, the excess water would run out and be wasted (as well as wasting the nutrients it picked up along the way)… but with hydrogel, it will absorb the water locally, so the soil remains moist but not “wet” and alleviate the potential for rotting, plus the water doesn’t run off so the nutrients stay in the pot where they belong.

    they might not be perfect, but like you said, under the right circumstances, they’re a very useful tool!

    • Yes, properly used, they could be. I doubt whether those harvested from diapers would be the best choice, though. I wasn’t trying to condemn hydrogels outright, of course, just to add a bit of “reasonable doubt” as to their efficacy in all situations.

    • Yes! It’s worked well with some of my plants that I’ve had root rot trouble with. I also think that aerating the soil has helped with growth. I wouldn’t use the hydrogel beads from diapers for my edible plants though, as it’s a different polymer than gardening ones, I believe.

  5. I have always enjoyed gardening in my adult life. Our home has been a showcase of the neighborhood but with that said it takes a lot of time and effort to maintain. But , the last couple of years I have not had any success with potted plants that i purchase at our local home centers and I think the problem is with the diaper like material that is added to the pot. Usually I will feel the top of the basket to see if it is dry and if so i will water it even tho the plant feels heavy, I notice my geranium leaves are starting to turn yellow which i contribute to too much water. By June of pervious years my potted plants were flourishing but not so for the past few years and i think it is from the diaper like material added to the pots. Has anyone else had this problem?

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