What size pot?

Discuss repotting, soil, lighting, fertilizing, watering, etc. in this category.
don
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Location: Carefree, Arizona zone 9b

What size pot?

Post by don »

I've seen lots of articles that warn not to" overpot". I'm not positive what this means (i want to assume that it means to use a small pot) and i'm not sure why this is an issue. Could someone explain please.

Also, I sometimes see hints that a plant should be in a "pan". Again, i'm not sure what this means ( a wok type pot?) or why this is important. Could someone please ex[plain.

Right now i have about 120 plants in individual pots the same size and for the most part they are doing fine but i want to do the best i can. thank you.
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Steve Johnson
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Re: What size pot?

Post by Steve Johnson »

don wrote:I've seen lots of articles that warn not to" overpot". I'm not positive what this means (i want to assume that it means to use a small pot) and i'm not sure why this is an issue. Could someone explain please.

Right now i have about 120 plants in individual pots the same size and for the most part they are doing fine but i want to do the best i can. thank you.
Okay, let's see if this makes any sense...

There's a big difference between giving cacti a free run of the roots in the ground vs. trying to do the same thing in pots that are too big for proper rooting behavior under confinement. This is a drying-out issue since potted cacti rely on water uptake through the roots to dry out the mix. If moisture in the soil mass exceeds the plant's ability to dry out the mix in a timely manner, that's a classic definition of overpotting. Some cacti are remarkably tolerant about it, others not so much -- you said that your cacti are doing well "for the most part", but if you can tell us about certain species you're having trouble with, then we'll discuss whether or not the problem is overpotting. Could be something else, although I may not be the best person to be giving more specific advice on the cacti you have in your collection. I'll help you as much as I can, and hopefully we'll have other members chiming in here.
don wrote:Also, I sometimes see hints that a plant should be in a "pan". Again, i'm not sure what this means ( a wok type pot?) or why this is important. Could someone please ex[plain.
Cactus roots come in all shapes and sizes, as do the plants themselves. The Internet is full of useless crap about how to grow cacti, so the basic rule of thumb should be -- size pots to the roots, not the plant.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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greenknight
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Re: What size pot?

Post by greenknight »

Right - the volume of the pot should be a little larger than the existing root ball. You want some space for new root growth, but not so much that it's going to stay wet for long.

Many cacti have shallow roots, and shallower pots are best for those. Back in the days when terra-cotta pots were used for everything, very shallow ones used for germinating seeds were called "seed pans", I think that's what they meant by "pan". They're pretty much obsolete, but with considerable searching I found a place that has traditional seed pans (just so you can see what I'm talking about - not recommending them, they don't appear to sell online anyway, and they're in Australia!): Handmade Terracotta : Seed Pan

Some other cactus species have deep tap roots, though. Those require deeper pots, can even push themselves up out of the soil if they're in too shallow of a pot. There is no "one size fits all" when it comes to cactrus pots.
Spence :mrgreen:
don
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Re: What size pot?

Post by don »

Thank you both...that is helpful and it makes sense to me. I think my problem is that I'm OCD (see picture)...I like the way it looks with all the pots being 7 1/2 inches tall...also, I found a huge bunch of terra cotta pots that were real cheap.

Also, when i said "for the most part", i guess i was being modest; they are all doing pretty good. My biggest problems have been pack rats eating some of my soft minor spined echinopsis. Also, I have not had much luck with rebutias. Other than that, i have had very few losses and most are flowering. I am definitely going to rethink my potting strategy; some are definitely overpotted.
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iann
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Location: England

Re: What size pot?

Post by iann »

I'm struggling to think of any Rebutias that could fill a 7 1/2" pot with roots :) That might be your problem. My OCD runs in the opposite direction, never be caught without the right pot:
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--ian
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Robb
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Re: What size pot?

Post by Robb »

I'm interested to know, Iann. Where does one acquire that many pots, I'm experiencing a pot shortage at the moment.
Buying a cactus a day will keep the madness away.
DaveW
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Re: What size pot?

Post by DaveW »

You buy plants in pots over the years then kill the plants Rob, so build up a stock of spares! :D

With about 1000 plants I must have evidently acquired a few pots over the years through buying plants in pots, since I am sure I never bought that many pots separately. If you buy plants by mail however your problem is they come ex-pot therefore you need to buy pots separately.

I am currently giving all my black pots to a friend who sells plants for a charity since I only like the terracotta pots Ian's collection shows. I find black heats up in the greenhouse much quicker than terracotta coloured ones unless tightly packed together to keep the sun off them.

In the UK you can often see dozens of plant pots dumped in skips (dumpsters) which if you ask the householder you can have since they buy bedding and other plants from the garden centres in pots, plant them out and then throw the pots away. Also try your local landscape gardeners as they buy plants for bedding out in pots then usually take all the redundant pots down the tip (dump). I was given a load by a landscape gardener who was just tipping them to get rid.

In desperation if you have to buy pots try the Internet or EBAY:-

http://www.ebay.co.uk/sch/i.html?_from= ... s&_sacat=0" onclick="window.open(this.href);return false;

For the retro gardeners who must still use clay pots you can get those off the Internet or EBAY too:-

http://www.ebay.co.uk/sch/i.html?_odkw= ... +&_sacat=0" onclick="window.open(this.href);return false;
iann
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Re: What size pot?

Post by iann »

Freecycle :) I do buy some pots. Fairly local to me there is a supplier of specialist high grade pots that last better in the greenhouse and also of hard to find shapes and sizes. I also was given quite a number of mostly 2" square BEF pots by another grower, presumably acquired in the way Dave describes. Buy (or sow) a plant in a small pot, eventually put it in a bigger pot and get left with the little one.
--ian
DaveW
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Re: What size pot?

Post by DaveW »

Some of my original BEF pots are just giving up the ghost due to UV degradation on the rims Ian after about 20+ years use. If only all plastic pots lasted like they did. The usual plastic ones only last a few seasons in the greenhouse before suffering UV degradation, becoming brittle and breaking. If course how long the pot lasts depends on how much sun it gets. In our tightly packed greenhouses in the UK it is the rims that become brittle due to UV degradation since the pot body is usually shielded from the sun by the other pots. The problem is when you pick up the pot by the rim, particularly if using tongs and it breaks dropping the plant on the floor or on top of other plants on the staging damaging them.

We can still get similar to the old BEF ones in the UK from the supplier Ian mentions but not sure they are still the same plastic, though they certainly last better than the usual ones. Most gardeners do not need long lasting pots suitable for prolonged greenhouse exposure so the normal cheaper ones continue to be produced, therefore long term growers continuing to use the same plastic pots are seldom catered for. Nurserymen of course quickly raise plants and sell them on, so long pot life is not a requirement.
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Robb
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Re: What size pot?

Post by Robb »

Thanks, guys!
I'll get around to solving my pot crisis ASAP :D !
Buying a cactus a day will keep the madness away.
DaveW
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Re: What size pot?

Post by DaveW »

Whilst you may acquire many spare pots in your time, you never seem to have enough of the size you now need!
keith
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Location: S. CA USA

Re: What size pot?

Post by keith »

Clay pots didn't work well for me when i lived in Phoenix AZ and plastic pots got too hot so I put plastic pots inside slightly bigger clay pots. The thicker clay pot walls took the furnace heat of the sun and the plastic pots didn't dry out so fast. i watered constantly in Az and used to have to add ice to my water along with vinegar. I made Ice in plastic drinking bottles. 80F water turned my cactus brown or just killed them.

i still put plastic pots inside clay pots come to think of it

Had the perfect size clay pot for this which I can't find anymore, figures. 4" clay drop pot fitted a 4" plastic pot perfectly cause it was slightly deeper than the plastic pot.
DaveW
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Re: What size pot?

Post by DaveW »

In open ground plant roots are buried so stay cooler, unlike pots where the sun can heat them from the sides of the pot. The old gardeners used to replicate this by plunging their clay pots up to the rims in peat or sand on the greenhouse staging's, the same can be done with plastic. However in the UK we usually pack our pots so tightly together to utilise valuable greenhouse space only the rims catch the sun, plus usually have an up stand to the staging edges to stop pots being dragged off which shields the outside pot sides from direct sunlight.

I would have thought those of you with climates where you can grow outside much of the year could find some way of plunging or shading the pots?
keith
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Re: What size pot?

Post by keith »

Plastic in Clay works Ok.
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Steve Johnson
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Re: What size pot?

Post by Steve Johnson »

keith wrote:Plastic in Clay works Ok.
Maybe extends the lifespan of the plastic too? Theoretically it sounds like that should work well.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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