There is always a lot to do about what type of pots to use for growing succulent plants, especially for Lithops.
There has been an eternally ongoing discussion about plastic pots versus terracotta. let it be clear: I hate terracotta for all the reasons listed below and so I've never used TC pots in all my 45+ years of growing succulents and I never looked back on that!
Major and general rule for choosing the pot size: ! DO NOT use over-sized pots! It serves no purpose, on the contrary. Chose a pot size that allow approximately 1 to 1,5 cm all around the plant. For Lithops, that is already huge!
One CAPITAL need for pots: Make absolutely sure your pots have enough and sufficiently large draining holes in the bottom! Standing moisture in the bottom will almost always lead to rot!
Lithops can build an extremely long tap root as can be seen in the Roots section. It is highly recommended to use tall pots which, let's mention it, are extremely difficult to find in an appropriate "small" size. I mean: not a bucket size. But let's face it: tall pots are not a "must" but it is an extra convenience.
So I've been experimenting gluing pots on top of each other using the famous TEC7 glue. Compared to the classic pot, they are at least 5 to 7 cm taller!
Round 6,5 cm on top of a 5 cm round compared to a 7x7x8 square pot.
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Square 8x8x9 cm on top or a 6x6x6.5 cm. 8x8x9 for comparison.
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- There is still and always an eternal discussion going on whether to use plastic or terracotta.
- For me the solution is simple. Plastic all the way so I'm not dependent of any uncontrolable water losses through the pot walls. Plastic pots let me have almost 100% control over the water household of the soil.
- I've gone through the trouble of listing up a number of "inconvenient truth" about terracotta. So bear with me for a second.
| - TC pots are heavy - TC pots are clumsy
- TC pots may be made out of alkaline clay which need acid washing before their use, with no warranty that alkalinity is getting washed out unless using acid which displaces the problem.
- TC pots have an horizontal water flow due to the permeability of the pot walls, which results in a number of undesired effects.
- The horizontal water flow is the result of TC pots having walls with strong capillary forces which means that water is constantly sucked up from the substrate, depleting the water capacity of the soil and evaporating it before it can be used by the plants. For plants that have low to very low watering needs, one could be watering the pot instead of the plants, ergo the pot sucks up all the needed water.
- This sucking effect makes that the pot always feels cold because the water is constantly evaporating from the outside of the pot, and evaporation needs energy, energy that is substracted from the pot wall. Ergo TC pot always feel cold because of this process but succulents like a warm foot.
- The horizontal water flow causes a constant flow of water plus nutrients towards the walls of the pot. The nutrient salts are partially stopped by the walls which causes filtration, crystalisation caused by overconcentration and which causes precipitation of the salts. The complex molecules that are built up in this way are mostly insoluble and may be alkaline of nature. That part of the most soluble salts that make it through the pores of the pot wall will inevitably crystalize and precipitate on the outer part of the pot because the water evaporates. It leaves the white stains that are hard to remove if removable at all because they are still encrusted in the pores.
- TC pots become virtually unusable when their walls are saturated with salts because they cannot be removed anymore as it is deposited in the TC pores and they are of very low solubility. They may be a constant source of alkaline content. A very long soaking in a moderately strong acid may help but is it worth the effort? Pots may need to be discarded after a while because of this.
- In TC pots the roots will follow both the water and the nutrients flow which is normal. But the flow is horizontal and hardly vertical like in plastic or glazed pots. That is why the hair roots build up as a thick, partly dead, layer of hair roots firmly sticking to the pot wall, like a thick layer of felt, because they try to get into the pores of the TC to get water and food. They may die because of an inappropriate pH and/or high salt concentration very near the pot wall. Transplanting becomes a nightmare because the root system is almost always torn off because of this "gripping to the pot wall".
- The soil in the pot is pushed toward an undesired gradient of pH and salt concentrations at high speed because the whole surface is evaporating water and the pot constantly sucks up water from the soil, and as such, the amounts of evaporation can hardly be controlled which in term makes controlled watering a gamble.
- Think of it: in a dry and hot climate you may need a plastic pot (or glazed TC) just to keep in some moisture that is beneficial to the plants. The sick habit of using pots that are way way too large and thus contain far too much soil, combined with the constant evaporation of water through the TC pot wall and the low needs for watering, one may be watering the pot instead of the plant in the end aka the plants in the pot may constantly try to survive on a water starvation regime. - Think more: what is the difference in characteristics between a plastic pot and a glazed TC pot? ... right, indeed! |