FlytrapCare Carnivorous Plant Forums

David F wrote:infact yes, I have had bad experiences, with chipped, or otherwise even sligthly damaged plain red clay. Not to mention with low fire, has killed a couple of plants much less sensitive than the carnivorous.

I wonder if it may have been overheating in the summer that killed the plants. I find it hard to believe that the red earthenware clay itself killed the plants. I've been growing several Venus Flytraps in a common red clay pot since last April, just to post photos this year when they come out of dormancy, to document that there is no ill effect on the plants from growing in a red clay pot for many months. Previously I have grown Venus Flytraps for several years at a time in common red earthenware garden pots before repotting, as well as plastic and stoneware clay pots, before I began to prefer polyurethane foam pots for their insulating characteristic. I'm referring to unglazed red earthenware pots, fired to maturity (some Mexican red clay pots are not fired to maturity, which means they are not fused much, and they contain additional materials to act as fluxes so that they can be fired at very low temperatures and fuse just enough to be a little stronger and harder to crack than greenware (unfired clay) but not much stronger).

David F wrote: In small doses is very harmless, but if soaked, this releases the potention of all the Iron oxide that may have been in the surface poors.

Unless the clay is green (raw, unfired) or fired only to a very low temperature, the red clay will not flake off of the body of the pot into the water. In raw clay or extremely low fired clay, the clay particles themselves can detach from the body of the clay, or even the entire pot may "dissolve" into a slurry in the water. But the particles of clay themselves do not dissolve, but merely disperse into the water in a way that would be harmless (I believe) to plants.

David F wrote:clay is so porous I have seen edges turn almost white

Although a white "bloom" of mineral deposits can occur on the outside of porous red clay pots, and although the discoloration can seem pronounced in contrast to the pot color, it is usually extremely thin, the deposits cannot easily reenter the pot (because the water generally flows to a much greater extent from the inside of the pot to the outside instead of the reverse), and it can easily be rinsed or scraped off from time to time. Although the discoloration may still be present, the amount of minerals it represents will be extremely small.

I'm merely stating my own thoughts from my own experience (not trying to start a controversy), and I am very curious as to exactly what might have happened to the plants that you think were adversely affected by the particular clay pots you were using.

This is why I started this post, do not worry yourself about starting a fight or anything. As mentioned the pot was damaged, and I'm pretty sure it was very lowfire, the point is, it was sold to me as a red clay ceramic pot, fit for plants, which infact is was not.

The white edges are not it leaking I imagine because it was harder and smoother than the clay around it, I really don't know what that means, it was like a super hard white chalk stuff.

As far as overheating, I don't beleive the plants would have overheated ie. there was much soil inbetween the soil and plants roots, and it was inside, with only 8 hours of filtered sunlight.

Again thank you for the inquiry, based on "your experiences" I have no real counter evidence to support. Because so far the only evidence presented has been by me, not trying to sound rude, but to say in your experience, and then state a fact, or theory, or principle that is not proved is not really helpful to a disection of why certain things may or may not have happened to either of us. Based on the evidence that may be actually applied to what situations we are talking about.

the white stuff is most likely what we in the paving industry refer to as 'efflourescence' or 'efflo' for short..

its the equivalent of salt damp in a house wall, except "efflo" is purely cosmetic and does not cause the cement to lose its integrity like regular salt damp would.

of course, both "efflo" and salt damp are caused by minerals leeching to the surface of the paver or cement.

in paving its usually because some fool put his pavers on dollomite or similar salty base and when it rains the capillary action of walking on pavers slowly draws a little moisture into the paver surface.
some pavers are worse than others..

fwiw

David, perhaps the "red clay pot" you had a bad experience with was not natural earthenware clay, but instead a man-made formulation with a lot of whiting added (chalk or calcium carbonate) to make the pot begin to fuse at a very low temperature (which is less expensive for the manufacturer). If one can scratch small particles or pieces of the clay from the surface of the pot with something that is hard and rough such as a key, then it very probably is a man-made ceramic mix and not natural red clay fired to maturity (the temperature at which the clay fuses like glass but does not deform nor melt). If that is the case, then it indeed could have broken down to some extent in water and leaked alkaline calcium into the growing medium, which could possibly damage the plants.

At any rate, I didn't want to post a photo so early while the plants were still in dormancy and the rosettes are so small (the Flytraps will seem to more than fill the pot during the growing season), but here is a photo I just took of a Fine Tooth x Red Venus Flytrap (and its division from last season) that has been growing in this red earthenware clay pot since April of last year (April, 2010), for a full season and now most of its dormancy. I'll post more photos in a few weeks when it breaks dormancy. I potted this plant in red clay last year in order to illustrate another discussion thread here at the FlytrapCare.com Forum by photo documentation this year, after at least a full year of growing. That other discussion is here: http://www.flytrapcare.com/phpBB3/clay-pots-t4880.html I would add that I planted Venus Flytraps in two clay pots: one that was sealed on the inside surface with acrylic artist's medium (which is pictured in the discussion thread linked to above) and one in an untreated, unsealed red clay earthenware pot (which is pictured here). Both red clay pots are part of the experiment and illustration for the discussion thread about clay pots.

I think it isn't the pure red clay, a very good copy though, thank you Steve, you have solved my dilemna, red clay is probably 100% safe, excluding that it collects minerals that may release and harm your plants. Thank your for all the clarification, and your evidence and examples were helpful.

Thanks for brining up this subject, David F, since it's an important one for carnivorous plant lovers. I've been annoyed in recent years by how many cheap, imitation red clay pots have been manufactured, of a very low-fired ceramic body that is similar to traditional, cheap, very soft and chalky bathroom wall tile (the part of the tile under the glaze), which is normally white (because of all the calcium carbonate), but with red iron oxide or other red colorant added to the ceramic or applied to the surface to give it the color of natural red clay.

I can usually tell the difference between them and real red earthenware pots but sometimes it's difficult at first glance. I have bought some of the imitations before only to realize they were not real earthenware clay later, and discarded them. They are often used for decorative purposes (silk and dried floral arrangements) but are not very good for live plants; they aren't weather resistant, chip and crack easily, and are so underfired that they are soft, almost powdery and can dissolve to some degree in water. Even scratching with a fingernail can often lift some residue or powdery material from the imitation red clay pots, which is not possible with real red clay that has been fired properly to maturity.

Anyway, thanks again for bringing the subject to everyone's attention, because it is important for carnivorous plant growers to learn how to distinguish real red clay pots from the imitation ones.