Non puoi far crescere una pianta in un vaso senza fori di drenaggio!

Le tue foglie gialle sono dovute al fatto che le radici stanno marcendo perché sono sedute in acqua fangosa.

Ripianta la tua pianta in una buca corretta con terriccio fresco e spera per il meglio.

L'insegnamento imparato?

What’s going on is that the plant isn’t happy, most likely because the water amount isn’t right, no matter what you may think. Plant leaves can turn yellow when the soil is too wet, or too dry - you have to figure out what’s going on.

You say you “make sure” to water it the right amount - but how do you make sure? and how do you know what the right amount is?

For instance, you can’t go by someone’s directions that say “water X amount every X days” - that’s no way to water plants. The amount of water a plant needs is dependent on a number of factors - the light, the soil, the size of plant and pot, the species, as well as other things. You really need to physically check soil moisture, all the way to the bottom of the pot*, and let the plant/soil tell you when and how much to water.

• * Checking moisture all the way to bottom of pot — often people will advise you to feel the top of the soil, or the first inch or two, and water when those are dry. Which can be fine, unless there’s moisture collecting in the soil near the bottom of the pot, which can lead to root rot down there, and yellowing leaves, even though the soil surface is dry. That’s why I’ve found it’s really necessary to check all the way down.

The second thing you need to know is the name of your plant, and what it’s moisture requirements are - or more specifically, at what moisture level it should be watered again.

The third thing you need to do is check moisture every few days, at least until you understand the needs of your plant, to make sure it doesn’t go too long without being watered.

If you want to know some more about this subject, you might want to check out Marlie Graves's answer to How often should I water my houseplants?