Does anyone have any experience with using water absorbing polymer crystals in pots?
I bought some of the crystals about 10 yrs ago specifically for use in containers. If you decide to try them, I suggest that you use them sparingly, and in large containers, mixing them well only with the soil placed in the lower 1/2 to 2/3 of the container. They expand like CRAZY, displacing soil in the process. In small pots (anything under a 5 gallon size, I'd say), they tend to work their way to the surface, creating a mess and a rather creepy visual.
IMO, they don't deliver on the hype, and are worth neither the expense nor the effort.
We used them for years, when we had a cheap source for them. There was at least one time when they saved us a bunch of roses, in an earlier drought period.
You have to know how to use them, however.
We kept a BIG plastic container, full of EXPANDED crystals.
Put the crystals in the bottom of your big container, and add water, then give them a day or so to absorb the water. They'll be these amusing clear Jell-O-like lumps. Mix THOSE in your pot, along with the potting soil. You'll find that the feeder roots will quickly find them and go right to them. It's sort of fun.
Once, we had a minor accidental spill of dry crystals on the front lawn. It rained, over night, and when we woke up, it looked like there were chunks of ice on the lawn. :-)
I think they're very worth-while, used properly, but a real mess if you don't pre-wet the stuff. And, NOWADAYS, in our area, they have become very un-affordable.
I have used the cheapest, unsented, unclumping form of kitty liter clay as a substitute.
They work great. I mix them in the soil in a big 15 gallon pot and water it for 2 days. Then you can use the soil. That and osmocote are wonderful for pots.
Our local walmart is sale pricing gargening items right now to make room for holiday merch. That's when I usually buy.
I did use them once some years ago but I didn't really care for them. They turn into an icky, gooey, jelly once wet and the ones that came to the top of the soil got slimy so I stopped using them. And you have to be very careful how much you put in because if you put too much in they'll gobble up all the water and the rose won't get any! You have what appears to be damp soil but it isn't releasing the water to the plant.
The climate may have a lot to do with how the water absorbing chrystals behave. Here in hot, dry S.W. Texas my experiece with them has been positive. I use them with everything I plant. I sprinkle a few of the dry grains in the planting hole for roses, annuals, and perennials and mix it dry into the potting soil for potted plants including roses. I've never had a problem with it. An exhibitor I know wets them using liquid fertilizer before mixing in the soil and said when she happens to uproot a rose the little rootlets are clinging to the fertilizer filled crystals. I don't do that, but I feel like they help a lot in keeping moisture that the plants can use in my thin fast draining soil. I order the medium size crystals by the pound from watersorb.com and they are much less expensive than in garden centers. The prices include postage and they mail them 'priority' the same day they receive the order.
When unfamiliar with them do as Jeri says and use them already expanded. One tablespoon will absorb a quart of water in about an hour. I used to use a quart mason jar, put in a tablespoon of polymer, and then filled it with water. Once you have a feel for how very much they expand you can use them dry, which is easier, without problems even in as small as a gallon pot. I mix them in the soil at the bottom of the pot, hollow it in the center, pushing it up the sides so that there is room for the root ball being transplanted. Do not add any additional to the soil you use to finish filling the sides of the pot or it will ooze up out of the soil and make a mess.
I was very specific. Polymers may vary by brand. The brand I use is Soil Moist.
Jeff Gillman, the guy at the U. of Minnesota who wrote "The Truth About Garden Remedies", didn't find any value to water crystals in his study, linked below.
Here is a link that might be useful: Water Crystal Study
Jeff Gillman presented that paper in 2004. I searched in Google Scholar and it appears that he never published the results in a reviewed scientific journal.
Here is a link that might be useful: Google Scholar reviewed scientific papers
Mike, thanks for citing that study. Henry, thanks also for your input.
Out of curiosity I googled the subject. I've not read all that came up, but here are two results.
From a study about growing birch seedlings:
"Although plants growing in polymer-amended medium had significally greater g, and E on occasion [roots and leaf surface I think] the results were too inconsistent to indicate the hydrogel was helping the birch seedlings avoid water stress. "
Another site was about growing 'pot' if all things... oh well, here's what they said:
"It is best to experiment and observe your plants, but as a general rule of thumb, if used correctly, the polymers should buy an extra three to five days between when you would normally water."
I once went 21 days between heavy watering in a severe drought situation. The plants with polymers, while definitely heat stressed,did not die; whereas plants without polymers did not survive this 21-day period of neglect."
There's a lot out there on the subject so who knows? Some day I might try a little experiment of my own.
I've used the crystals in the past (in pots and window boxes). Assuming the ones in my old container are still viable, I might try using them again -- but only if I were planting new plants directly into my garden under drought conditions.
As with practically everything else modern chemistry has given us, polymer crystals present an array of potential health and environmental concerns that (to my knowledge) have yet to be resolved.
I'm linking to an interesting, easy-to-read pro & con article on the crystals written by a professor of horticulture at Washington State U.
Here is a link that might be useful: Super-Absorbent Water Crystals
The easy to read article presents undocumented information (the one reference given did not work for me).
The font of all, h. kuska, says tsk-tsk, so kindly disregard my link and Dr. Chalker-Scott's statements.
Here are the references for that easy-to-read article:
Here is a link that might be useful: hydrogel references
Thank you for the references, but there is no indication as to which reference refers to/supports which statement.
I just do not understand that style of presenting scientific information.
The following link is to a full (not just the abstract) 2012 reviewed scientific paper. In the introduction, the authors are expected by the reviewers and the journal editor to present the significant previous research and explain why the present research is needed.
The concluding sentence in the abstract is: "The above-mentioned results thus reaffirmed the suitability of gel for sandy soil because it improved the water availability of the sandy soil for a longer period (nearly 22 days, which corresponds to the irrigation interval of most agricultural crops), while gel was found unsuitable for black soil, in which the critical soil water content was reached early (4Ã¯Â¿Â½7 days)."
H.Kuska comment: "black soil" is defined as "black clay".
Here is a link that might be useful: link to full paper
Thank you all. I think they may do well for me . I'm having to water many of my pots twice a day.
Self watering pots work wonders too. I like them with small roses and strawberries and also things that need constant moisture like delphiniums. You want to use a potting mix that is not going to get too soggy with the self watering pots.
Using them dry is certainly easier (and doesn't require planning ahead). However, Kim cautioned me one time about being careful handling them when they are dry, to not inhale any dust - you don't want it in your lungs for obvious reasons.
Good advice , Lagomorphmom. I imagine the dust from these things would be pretty nasty in the lungs.