FlytrapCare Carnivorous Plant Forums

I replanted my Flytraps in large clay pots. I noticed afterwords that most
literature recomends plastic or ceramic pots. Will the clay pots harm my
plants ?

After a certain amount of time, check out the soil moisture post.

I don't use clay pots as some of them can affect the pH of the soil

This long post is an explanation of clay, clay pots, imitation clay ("clay bodies" and ceramic formulations) and their safety or danger as carnivorous plant containers

Some clay pots are OK, and some are not. The common red clay pots are generally OK to use, IF they are the traditional red clay earthenware fired to maturity (to the point where the clay fuses mostly into ceramic glass). Red earthenware clay is composed of silica (silicon dioxide) and alumina (aluminum oxides) and a few trace minerals, like the iron oxide that gives it its red color. These materials are virtually insoluble and inert once the clay is fired, and therefore harmless to carnivorous plants.

There are two basic classes of clay pottery: lower-fired and higher-fired. The lower-fired clay, like the red earthenware clay pots, tends to be porous, while higher-fired clay like stoneware and porcelain tends to be vitreous (nonporous).

Either lower-fired red earthenware or higher-fired stoneware or porcelain are fine to use as planting containers for carnivorous plants, because they are chemically inert and virtually insoluble. However, with the porous low fired clay such as common red clay earthenware pots, a "bloom" or stain (usually whitish) may be left on the outside surfaces of the pot when water evaporating from those outside surfaces leaves behind whatever small amount of solids that were dissolved in the water. Just rinse or scrub those thin deposits off, and things will be fine. If both the growing medium and the water are low in dissolved solids, then there will be very little buildup of mineral deposits anyway, although even a small amount will be visibly evident as a light-colored patch on the outer surface of the pot. One thing to remember though when using porous earthenware red clay pots is that the do wick water from the medium, which will dry out perhaps twice as fast as in a plastic pot, so it's good to use a slightly more moisture retentive growing mix when using red earthenware pots.

However, all that said, here is a warning:

There is another type of "clay" pot that is not at all appropriate for use with carnivorous plants, and these are the clay pots that are not actually made of pure clay, but are instead "clay bodies," artificial ceramic compositions that can and often do contain soluble chemicals and minerals that will probably harm carnivorous plants as they change the pH (acidity or alkalinity) of the growing medium and introduce dissolved solids to the medium and water. These types of "clay" are very low fired, are not fused for the most part into a ceramic glass, and should be avoided. They are generally very porous and soft. Examples include much bathroom and wall tile and many imitation red clay earthenware pots that are not actually earthenware clay at all, even though they may be the same color of red or terracotta.

So, if a person can tell the difference between various types of clay and clay bodies, then it is fine to choose real clay containers for carnivorous plants, whether porous low-fired unglazed red earthenware or high-fired vitreous stoneware (both glazed and unglazed stoneware). Usually stoneware is OK to use regardless of whether it has added ingredients or is just natural stoneware clay, because it is fired to such a high temperature that all the materials are fused into a nonporous and insoluble mass. But the imitation low-fired red clay pots are harmful and should be avoided.

Best wishes and good luck. --Steve

Steve (and others),
I have seen a terracotta pot "sealer" sold in craft stores. The idea is to keep moisture from getting to furniture as well as to preserve any decorative painting on the outside of the pots.
Has anyone used this sealer with VFTs?
I would think it would keep the pots from affecting the PH, regardless of what kind of clay they're made from, as well as reducing the tendency of the porous ones to dry out. (Unless, of course, the sealer itself is somehow harmful to the plants.

There are two types of such sealer that I'm aware of: a silicone based sealer and an acrylic based sealer. My family used to use the silicone kind in a small pottery business we had. I believe the silicone kind is also used to seal wood decks and other materials, whereas the acrylic type is often used with ceramic tile and in wood-floor finish products (like "floor wax"). Both might work fine, but I think that the acrylic type would be safer to try on clay pots because it forms an immovable film whereas silicone is composed of loose particles that may move into the growing medium (I don't know for sure).

I'll bet that the specific clay pot "sealer" you refer to is acrylic based and may even be exactly the same stuff that is used as a sealer for grout between tiles. It would be much less expensive however to just buy a small container of artist's clear acrylic medium (which is simply very concentrated acrylic, not watered down like the other sealers mentioned; it looks like a very viscous white gel although it dries clear) and just add water to some of it to make a nice consistency to paint inside the red-clay (or red clay lookalike) pot. Acrylic forms a tough, more or less waterproof film.

I happen to have some of this artist's acrylic medium, so I might try doing exactly what I just suggested, plant a Venus Flytrap in the treated pot, and see what happens. I imagine it will be fine.

OK-- I coated the inside of a red clay pot (just natural earthenware clay, not an artificial "terracotta" lookalike) with some Grumbacher Artist's Acrylic Gloss Medium, and here is the result-- Next, I'll plant a couple Venus Flytraps in the pot and see how they fare during this growing season!

Steve

Nice steve.
Will it be in your greenhouse or outside facing wind/rain etc?

You think the minerals in the clay will effect the varnish?

Ron.

Ronnie wrote:Will it be in your greenhouse or outside facing wind/rain etc?

Both. Greenhouse at night, outside many days.

Ronnie wrote:You think the minerals in the clay will effect the varnish?

Not much if at all. Acrylic is virtually waterproof when dry, and forms a tough coating. In addition, red earthenware clay has virtually no soluble material in it. The usual warnings about red clay pots and carnivorous plants stem I believe from the tendency of red clay, which is very porous, to absorb mineral salts and other dissolved solids from the water and medium, or from tap water if it is used to wash the clay pot, and then allow those solids to redissolve into the water and growing medium. In reality this does not readily occur because the water flows from the _inside_ of the pot to the outside, carrying dissolved solids _away_ from the growing medium and roots.

That is not to say that red clay pots will allow one to water with regular tap water, however!

I believe I heard someone say that you can wash the minerals out of a clay pot every day for a week, and then it can be used safely with carnivorous plants. But just to be safe, I would stick to plastic pots as I usually do.

Yeah, too much time and WAY too much grey area for me. Ill stick with plastic and glazed thank you!

I just re-potted my vft from a 20 oz styrofoam cup to what I believe *MAY* be a glazed pot. I found algae growing along the inside of the cup and covered the soil... Anyhow would anyone care to enlighten me if this pot is okay to use? My plant is in very bad health (possibly from overwatering, sunburn or that bad algae that developed in the soil). It lost three larger traps and three new growths within one week and the new growths seem stunted as they have been the same size and position for quite a few days. The stems and hairs around the one mature trap's mouth have a slight yellow tint to them too.

The third picture is the bottom of the pot which is unglazed, if I bottom water will this leech minerals into the soil? (if this pot is even okay to use)

While I've posted, could any possibly diagnose the issue that is harming my plant? I bottom watered once every one to two days and the plant was healthy until I went away one weekend and it went unwatered for three days. Ever since then the stems look burned and dying while the new growths appeared burned too. My vft receives 3-6 hours of direct sunlight a day (unless its cloudy like it has been in NYC for the past few days.) If you need any other information ill be happy to tell you.

Thanks.

GammaZeta wrote:would anyone care to enlighten me if this pot is okay to use?

That looks like a low-fired glazed earthenware pot, equivalent to a common red clay pot with a very soft (easily meltable) glaze. The glaze may contain lead, a common flux to make glazes melt at low temperatures, or may contain a lot of calcium or some other flux. In the acid environment of carnivorous growing medium, a little of the glaze ingredients may enter the growing medium, but not much. The glaze makes the normally porous earthenware clay nearly vitreous (nonporous; water can't flow through it) except where the glaze may crack or form hairline fractures, but that is not a problem for carnivorous plants.

The reason that both the pot and the glaze are fired at relatively low temperatures in the kiln (as compared to high-fired stoneware or very high-fired porcelain) is that earthenware clay, which is often red but not necessarily, will melt into a puddle of glass if fired at higher temperatures. For this reason, low fired clay is sometimes brushed onto high-fired objects before placing them in a kiln to form a glaze.

After all that mostly extraneous information, I would say that the pot you chose is fine to use for growing Venus Flytraps and other carnivorous plants.