Indoor cacti and succulents as well as other kinds of houseplants can be watered using various methods.
Watering from the bottom is a good method for cacti and succulents because this is less likely to lead to soluble salt buildup. This is possible only with smaller plants. The most practical way to do this is to set the potted plant into a shallow pan holding three to four inches of water or in a sink filled with several inches of water. In this method, the water rises through the drainage holes up into the potting soil. Once the soil is thoroughly saturated, the pot should be removed from the water. Then, drain carefully to remove all the excess moisture from the bottom of the pot.
Cacti and succulents can be watered in the ordinary way by pouring the water into the top of the potting soil. In this process, the first step is to remove the pot from its cache pot or saucer. This method is suitable for small and medium size plants. I usually set the pot in the kitchen sink so the excess water can easily run through the pot and down the drain.
Large cacti and succulents canít always be moved to a sink or other location for watering. It is usually more practical to leave them in their saucer. However, when you pour water into the top of the pot, the surplus will drain into the saucer. By various means, you need to remove this water even if the pot is too large to lift. For example, you could put a layer of pebbles in the saucer. Do this when you transplant the plant into its new pot, and set the pot onto the pebbles. Then, when water collects in the pebbles, use a turkey baster to siphon it out. In order for this watering method to work, the pot needs to be elevated enough above the saucer bottom so that the water will be easily collected and removed.
Capillary watering mats are used for some types of houseplants, such as African violets. However, this method wouldnít be suitable for many kinds of cacti and succulents. The exceptions are the ones that need a rather moist soil. Example would be the Christmas and Thanksgiving cactus. In general, if the cacti/succulent species is suitable for hydroponics or hydroculture, it can be watered with a capillary mat. Self-watering pots are also good for these same types of plants, but not for desert cacti, or ones needing dry soils.
Whatever method you use, the water needs to moisten the soil completely. Otherwise, the soluble salts may become a potential problem. This is more likely to happen if you add a lot of fertilizer, or are adding a little water at frequent intervals. Soluble salts become visible as white rings around the inside rim of the pot.
For mixed plantings, such as dish gardens, the entire container is treated as a whole when watering. In other words, you can single out one plant in the pot for watering. be sure that all the species you select have compatible water needs. In other words, donít mix desert cacti and jungle ones, such as the Christmas cactus, in the same dish garden. These two types have different water needs.