Updated: Nov 5, 2020
Whether your succulents are in a small container or in the ground in your garden, the most important thing is to observe them. Why? If they look limp, the leaves look shriveled up or brown and wrinkled like paper, they are most likely under-watered. If the leaves are squishy or look plump, they are probably over-watered. The best way to water them is to use a watering can and slowly/gently pour water over the soil. When you see water dribble out the bottom, stop! Don't water it again till it's thoroughly dry.
This Kalanchoe 'Panda plant' is over-watered. See how the leaves on the right side of the photo are standing up and fuzzy. That is how they should look. The ones on the right, however, are flopped over the edge of the pot, stacked on each other. They drank too much...seriously! Succulents do that, it's their instinct to absorb water and store it in their leaves when it's there. If they absorb more water than they can store, however, the 'cells' in their leaves (think storage reservoir balloons) burst because they cannot hold it all. It's just their nature to take in water when it's there, because they are acclimated to arid climates that do not get water on a regular basis. They see water, they take it, and boom!
Do you see that yellow leaf in the upper right hand corner of the photo? That is dry and turning yellow because it needs water. The leaf on the middle pinkish one is also looking thinner and drier, kind of orangish yellow. See how chubby the leaves are on the middle one, but the one on the upper left side is starting to show signs of needing water. It's so pretty with the black rocks on top, but it also makes it hard to feel how dry the soil is.