Pointed, hard to kill and able to live in the least desirable corners of a room, perhaps it make humorous sense why it's called mother-in-law's tongue (Sansevieria trifasciata). Also called snake plant or simply "sansevieria," it grows outdoors in tropical regions into large clumps of plants, perfect in hot, dry soil garden sites. Its fleshy rhizome root likes to spread, filling up the container after awhile. Mother-in-law's tongue grows nicely in the home since it tolerates arid air, low to bright light and infrequent watering.
Mother-in-law's tongues demonstrate a wide tolerance for light indoors when grown as a houseplant. In nature it prospers in direct sunlight or under the dappled shade of tropical trees. So, consider locating the mother-in-law's tongue in as much light as possible indoors for best leaf stature, color and overall plant health. The plant also is remarkably able to survive and grow ever-so-slowly in the dimly lit areas of a room, opposite a window. Too little light leads to weak, floppy leaves eventually, and often over-watering quickly leads to the plant rotting and collapsing.
Plant it in any fertile house plant potting mix or cactus soil blend that is well-draining. Ensure the container has drainage holes in the bottom. Avoid any topsoil in indoor containers, as it will turn rock hard and likely not drain well or moisten when you do water. The potting mix must have some texture and substance to it so it can support the roots and tall leaves.
When in doubt, err on the side of slightly dry soil when growing mother-in-law's tongue as a house plant. Allow the soil's surface to become slightly dry to the touch in the top 1 inch of soil. Then add no more than 1 inch of water to the container. If your plant is in a warm, very sunny or bright indirectly lit room, water once every week to ten days. In cooler rooms, or those with dimmer light levels, water less frequently, perhaps once every two to four weeks, if not slightly longer. A plant can last for months without water, but often leads to plant rot once watering resumes after such an extended drought indoors.
Since mother-in-law's tongue is a relatively low water-use plant, don't bother with liquid fertilizer applications. Utilize granular, well-balanced house plant fertilizers to sprinkle atop the soil surface. Consult the product label for dosage. When you do water, the nutrients slowly and gradually reach the roots. Over-fertilizing leads to huge plants and crammed roots, and fertilizer in winter when light levels are lower can cause pale-colored or very scrawny leaves.
Prune away any brown, dead or soft and rotting leaves when you see them. If the leaves are rotting, modify your watering regimen. Make sure you water only when the soil surface becomes dry: always underwater house plant sansevieria in order for it to have longevity. Occasionally add new topsoil to the container to fill in gaps at leaf bases or other depressions or holes.
Consider replanting large mother-in-law's tongue clumps in spring, cutting the roots and planting them into new containers. Throw out rotted plants or very tall leaves that will not stay upright after you transplant them into pots. Throw away plants if desired and purchase new, inexpensive potted specimens from the garden center.