Why do novices always use clay pots?

[DaveW]

A friend of mine always says you can grow cacti in anything providing you get your watering right. He means both types of pots and soil mixtures. Clay pots require a different soil mixture to plastic which drains slower. The problem occurs in certain climates when you try and use the same soil in both, where one either dries too quickly or the other too slowly. If you are getting rotting in plastic then your soil is not porous enough. For instance all you using purely mineral soils like pumice and cat litter that are free draining will be ideal for plastic, whereas adding some humus to those for clay pots in hot countries will help water retention. Also whatever pots you use watering at the wrong time will rot plants!

I have been growing cacti since about 1958 Eli and most of that time in plastic pots, so 1000 plants in plastic pots are now far less trouble than my early days growing in clay pots since I don't want to be watering every week in summer. Whatever you grow in you will inevitably loose some plants and you can't always put it down to the type of pot. Even if you only loose the same small percentage of plants each winter (in countries that have one) your losses numerically go up the more plants you have.

I should have added previously that my main objection in judging pots in plant shows rather than just the plant is it then becomes in part a gimmicky ceramics show and discriminates against those that grow in plain plastic pots, therefore perhaps that's part of why there has been a slow take up of plastic pots by cactophiles in the US as opposed to the UK?

A British cactophile reported when he went over to the US he was asked to help judging a cactus show and on remarking on which was the best plant in the class his fellow US judges pointed to another and said something along the lines of "never mind the plant look at that magnificent pot", and that was in a supposed show for plants! That would not happen in the UK since all our judges have to be tested for their suitability and accredited, no matter how well known or how long they have been growing plants and have to judge to the BCSS set rules which don't point pots or discriminate between plain plastic or fancy ceramic ones. No difference in principle to people who judge national exam results, since you want uniformity of marking throughout a country without too much personal bias creeping in of those doing the marking.

In the UK you can take a BCSS test to be either solely a cactus judge, solely a judge for other succulents, or both tests to allow you to judge both. Also judges have to keep up to date since they have to take a test again every 5 years to take into account new classifications and discoveries in the mean time or loose their accreditation.

http://www.bcss.org.uk/show_com.php" onclick="window.open(this.href);return false;

[C And D]

A friend of mine always says you can grow cacti in anything providing you get your watering right

This could not be more true.
You can grow cacti in any soil or any container if you get the watering right.

So if clay works for you, keep it up. I could see it might be helpful in cooler climes.

Plastic is a poor conductor of heat, as is clay and ceramic.

As far as having green plastic pots heating up too much, you can just stack them close together. I have many plants in flats completely filled so there is no room between pots. The plants do fine, ever been to a cactus nursery? they have greenhouses full of flats all filled to the brim.

I think another problem for novices is; finding good plastic pots, I used to ask nurseries if I could have their old pots, and would clean them. Now I buy them by the case, which no novice would want to do. So novices are stuck with using ceramic or sealed clay, or using the plastic pot the plant came in.

----
I have some very small pots of Pelecyphoras and other mexican slow growing things on my top shelf that gets above 110 degrees daily.
I'm sure the pots and soil may heat up past 120, but they seem to love it, and they won't put on any significant growth without that heat, since I can compare growth with the same plants on the regular bench below.

For me, the best way to make sure that I get proper soil drying between waterings, is by using small pots and lean soil.

[jp29]

I don't believe I have grown a cactus in a porous clay pot since about 1961. I use square plastic pots (black, green, terra-cotta colored) 2"-4" for my small to medium size plants and round plastic pots for my large and specimen plants. I have never had any over-watering issues (I can't remember the last time I lost a plant to rot ) even though I grow water-sensitive cacti almost exclusively. But I do use very porous and well aerated growing media -- 80% washed pumice plus 20% aged and weathered pine bark -- or straight pumice. For me, besides their light weight, one great feature of using plastic pots is the ability to easily slide established plants out of their pots (and afterward slide them back in) in order to examine the condition and health of the root ball structure. I do that constantly - I can't do that using porous clay pots.

Here are pics of some Discocactus & Melocactus root balls:

[K.W.]

83982

83983

And so do the roots of a plant in a clay pot. Fine roots only on the cup, where the water evaporates. To change the pot without disturbing the roots, impossible.
I use plastic pots since 1978, had only positive experiences with it.


83979

83986

One can perhaps argue about the aesthetics, with my kind of plant care - climate, substrate - but not about the material of the pots.


83970

A round pot often looks better, but there are also to have in plastic.


K.W.

[jp29]

BTW, Mrs. P. (SWMBO) objected to the appearance of the round plastic pots in which I was housing my large specimen Melocactus & Discocactus plants in our front garden a few years ago - she thought the traditional terra-cotta clay pots looked much nicer. So by way of a craven compromise I waterproofed some porous clay pots (similar to the way Steve Johnson waterproofs his) so they would be non-porous. But by then I was an arthritic eighty year old and I couldn't lift the darned plants - so I pleaded my case and eventually went back to the plastic pots (a lot of de-potting, potting and re-potting there!).

[BarryRice]

I grow in plastic for all the aforementioned reasons. However, sometimes when I lift a pot the pot slightly deforms, and I can hear the pumice shifting (I grow in a pure mix of pumice and crushed granite). I wonder if this might cause some minor damage to the roots, that you wouldn't get from a rigid clay pot?

Barry

[DaveW]

I think, as has been said Barry, the problem is finding the correct type of plastic pots for our cultivation. Most plastic pots are designed for the nurseryman and general gardener who don't grow the same plant in a pot in very high UV conditions for years or in warm greenhouses in summer as we in many parts of Europe do, therefore rigidity and being long lasting is not an issue.

We used to have some great pots in the UK made by a firm called BEF some of which I am only just throwing away due to constant use and UV degradation on the rims after 30+ years of use. I was told in the past these were made from polypropylene rather than polystyrene but I do not know if that was true, although this link I found on the web seems to confirm it:-

http://www.hartley-botanic.co.uk/featur ... e-bef-pots" onclick="window.open(this.href);return false;

However polypropylene pots still seem to be available but are not so long lasting, so that cannot be the whole story?

As to pot deformation affecting roots this may even be an advantage. It is known that windrock on trees strengthens the root system and some gardeners even used to grip and shake the trunks of young trees to encourage this. I did read a year or two ago that Kew removed some large trees in either the Palm or Tropical house as a safety measure since not being subjected to normal windrock indoors they feared their roots would not be strong enough to support their height and might fall on the public.

[keith]

Plastic fall apart in the sunlight. I switched to plastic in AZ and am switching back to clay in California for anything over 2" diameter. Plastic pots lose soil out the drain holes.

The thicker plastic pots work well a different kind of plastic but they are hard to find though and they still spill soil all over the place out the drain holes.

Paint the inside of the clay pots I have done this.

[DaveW]

I think the argument really comes down to porous versus non porous containers, whatever material they are made of. Glazed or waterproofed terracotta or ceramic pots, tins and plastic pots are all non porous containers that behave similarly, as against traditional porous terracotta pots where only the untreated qualifies since I can't think of any other type of plant pot that is porous?

However I bought some cacti in what looked like untreated terracotta pots with no drainage holes in them, therefore thought I would try the idea of wiring moss around the pot to grow Rhipsalis in and just water into the pot, relying on water to seep through the sides. However I don't know what the clay used was and though they were certainly unglazed even filling the pot with water for weeks I could not get any seepage through the sides, therefore all apparently unglazed pots may not necessarily be as porous as you think, it could depend on the clay and degree of firing used:-

http://www.claytimes.com/reference-guid ... asics.html" onclick="window.open(this.href);return false;

After reading the link above I suspect my pots may have been verging on stoneware.

[CactusFanDan]

I have a big Leuchtenbergia prinicipis in a clay pot, but I'd rather move it out and into a bigger plastic pot. If you can't grow plants in plastic pots without them rotting, then perhaps you need to smash up your clay pots into small chunks and mix them into your soil.

[Brunãozinho]

I have a question for all of you who glaze the inside of clay pots, do you have to do it again sometime? How often do you have to glaze the pots?

[pinkham]

Thanks for the info everyone. I'm about a year into my love affair with cacti. I have all pretty common plants so far. Before I read this I thought the debate over plastic vs. terra cotta pots was just a matter of preference....just like soil. lol Everybody says their soil is the best. I rooted a few prickly pear cactus pads this past winter in a plastic pot. This spring I separated them and put one in a glazed pot. Maybe it's just a coincidence but the one in the plastic pot grew a new pad.
As luck should have it only 2 of my plants are in unglazed pots. I'll be sure to transplant them this spring into plastic pots...using my own soil mix, because it's the best ( Ha ha) just kidding.

[iann]

Maybe it's just a coincidence but the one in the plastic pot grew a new pad.

All other things being equal, the plastic pot will retain far more water. Greedy plants like an Opuntia will grow faster. Sensitive plants might die That in itself isn't a reason to go either way, but you should certainly be aware of it when trying to mix'n'match or move from one to the other.

[pinkham]

so, then is there no real answer to the question? I love terra cotta pots and would use them in a second if it didn't make a difference.

[iann]

so, then is there no real answer to the question? I love terra cotta pots and would use them in a second if it didn't make a difference.

It does make a difference, no doubt about that, and far more than just preference. Read the whole thread to see what all the differences are. My recommendation is not to use porous pots except in a few very particular cases. If you use them already, then you'll have to adapt your soil or your watering, or both, if you change to non-porous pots.