What Plants are Sensitive to Mineral Buildup on Clay Pots

Hello!
I use primarily terra cotta pots for all of my houseplants and I've noticed that many of my pots now have white mineral buildup on the outside...could this be a problem for some houseplants? Are there certain species that are sensitive to this? If so, what are they (main ones) or where could I find the list?
Thank you!
Katie

The salts in the soil which cause that will be there in plastic pots too, you just won't see them on the pot the way you do with clay pots. Most plants will be sensitive to salts that build up in the soil over time, that's why it's important to water thoroughly to flush some of the salts out, and also to repot in fresh potting mix from time to time. I'm sure there are some plants that are more sensitive than others to salt buildup, but growing them in a different type of pot won't get rid of the problem so there's no reason to stop growing your plants in the clay pots.

Thank you!

Hi Katie, I know of no plants that suffer from this salty build up that you notice on your clay pots, as Ecrane mentioned, this white crusty stuff is found in/on all pots (even our more decorative ones, but we don't see this as easy on other pots due to the colour and materials the pots are made from.

Personally I like /love my clay teracota pots for various reasons, A) the wonderful colour,
B) the easy sizing, C) they don't dry out so quickly, D) I can tap the pot and the sound tells me IF I need to re-pot as a dull tone is saying the pot is full of roots, E) The teracota pots hold moisture better than plastic in my view and keep the roots cooler in summer and warmer in winter. but I was brought up to learn all that from helping my late Dad. You must make sure the Tract pots are treated to protect them in freezing weather or they crack, if you live in a severely cold zone.

Every winter we would fill an old baby bath with warm water and have a stiff wire brush and that would begin the cleaning of all the pots used over the season, this soak in warm water and a good brush would remove the buildup of the white salty mineral and also let you break up cracked pots to use as drainage covers for the bottom of the pots when next used, this clean also meant no bugs or diseases were left to grow and spread while the pots were in storage, I have to admit to this day I love the sight of lots old used teracota pots laying out in rows and all in proper sizes, it just reminds me of my childhood as each gardening season had a beginning and an end. I just wish I had the time, the determination etc to have my greenhouse tidied out each year as my old Dad had his, but hey, we do but try, ha, ha, ha.
Happy gardening, WeeNel.

Katie - clay pots are permeable, allowing gasses to pass through container walls fairly freely, and liquids to pass to a lesser degree. The deposits you see on the outside of your pot are dissolved solids. That is to say that there are dissolved minerals and fertilizer salts in the soil solution that pass through cell walls in water. When the water with its dissolved solids come into contact with the air surrounding the pot, the water evaporates and leaves the (formerly) dissolved solids behind. The deposits you can SEE, are harmless, even if left on the outside of the pot - simply because if they are clinging to the walls, they are not in the soil solution. They are, however, evidence of OTHER dissolved solids still IN the soil solution. These are the dissolved solids that do give cause for concern.

We want to keep them at a low level because the lower the level of salts in the soil solution, the easier it is for the plant to take up water and the nutrients dissolved in the water. We don't want the level so low though, that there isn't enough fertilizer in the soil to satisfy nutrient requirements. You can see that there is something of a balancing act going on. If you want to know more about how to keep this balance favorable, just ask.

Because the walls of terra cotta pots are permeable, they allow water vapor and water to pass through. This means that clay pots dry out much faster than their impermeable counterparts made of plastic, glazed clay, ceramic, and other impermeable materials. That is also why terra cotta helps to keep roots cooler - by way of the evaporative effect I just mentioned. Since they are permeable, they also allow potentially harmful gasses to pass out of the soil. The excess CO2, as well as the sulfurous gasses and methane that can inhibit root function, pass out of soils in unglazed clay more readily than other pots. Also, the need to water more frequently is a blessing in disguise because when you water, you are assisting mechanically in forcing these gasses from the soil more often.

I grow a large % of my plants in terra cotta. I like the health benefits and enjoy that nice patina that comes with age, worn by my older pots.

Al