There are lots of plants, such as cacti and bromeliads, that have limited root systems and grow very slowly. As long as we feed such plants with fertilizers, they may not go into a visible decline for years. Eventually, however, growth will slow and the plants could stop putting out new leaves and branches. The appearance of slender little rootlets outside the pot is one sign that it is time to find a bigger home for the plant. The need is urgent once the rootlets form a mat on the saucer underneath the pot.
Leaves wilting and foliage turning a lighter shade are additional clues.
The definitive test of a houseplant's need for repotting comes when you take the plant out of its pot and check the condition of its roots. A densely tangled root network, conformed to the shape of the pot, is an obvious sign of crowding. Experienced indoor gardeners counsel against transferring a plant into a much larger pot. Repotting should not be done until a plant is in active growth this spring. It is important for the roots to start burrowing immediately into the fresh potting mixture, which the plant will not do while dormant.