Why are the tips of your spider plant brown?

I could be a mixture of several different things. First thing is over watering. Let the plant dry out during the winter months. I usually stick my finger into the soil up to my knuckle. If it doesn't feel wet I then water. During the summer I water once a week.

Another thing that causes browning especially on the tips of the leaves is salt build up in the soil. Give the plant a good flushing with a gallon or more of distilled or reverse osmosis water once a month to reduce the salt content in the soil.

Another thing is that spider plants are sensitive to fluoride that is used to treat water. If you know that your water contains fluoride it would be best to use distilled or reverse osmosis water when watering.

If all else fails and your still having issues repot the plant. Use a coarse well draining soil. I have used cactus mixes with good success.