It is a general garden practice to dig and divide perennial flowers and ornamental grasses every three to four years. Helping to alleviate overcrowding increases plant health and vigor. We often forget that houseplants are actually tropical outdoor plants that tolerate the confines of clay pots and dim south-facing windows.
If you are ready to regain floor space in front of the sliding glass door, start thinking about moving houseplants outside and allow them to stretch their roots a little.
Spending the summer outdoors can revitalize many houseplants. The fresh air, natural rainfall, and bright light is like a vacation to the tropics from where they came. But making the move slowly helps them transition successfully. Begin by moving them outside during the day and back in at night. While outside, do not place them in direct sun. Their leaves are not ready to handle the bright light and will sunburn. Likewise, their leaves are vulnerable to tearing and breaking, so provide them good wind protection. Keep in mind that they will dry out rapidly outdoors. Depending on the weather, they should be ready to stay outside for good by the middle of next month.
Encouraged by the long days and fresh air, houseplants usually will put on a spurt of growth as well. Eventually, they will outgrow their containers and need to be repotted. To check if your plants are becoming rootbound and need a larger pot, inspect the root system. Do this by lifting the plant from the pot. Watering several hours before the operation will allow the plant to be removed more easily. For pots that are 8 inches in diameter or less, place one hand over the top of the pot with the stem of the plant passing between two fingers. Next, turn the plant upside down. Lightly tap the edge of the pot against a table. The root ball should come free, and the plant will fall right out. For pots that are more than 8 inches in diameter, a bit more encouragement may be needed. Place the pot on its side and tap lightly the top edge of the pot with a rubber mallet. Rotate the plant a few degrees and repeat the procedure until the root ball releases.
Inspect the roots once the plant is free of the pot. A large visible mass means the plant needs to be repotted. If the original pot is less than 10 inches in diameter, move up an inch in size. If the pot is 10 inches or larger, increase the size 2 inches.