One of the questions we get a lot about house plants is when to replant. The best way to tell is when the plant has stopped growing. This lets you know that the roots have reached the maximum growth potential for the pot. When the roots can no longer stretch and grow this can cause them to fight for room in the pot and cause the plant to become root-bound. Root-bound plants will not grow and if they remain in the pot for too long may even die.
When you do decide to re-pot your plant find a pot that is about 1/4" a size up from the one you are currently using. If you are using a metal container make sure that it has a plastic liner. Metal containers can rust and harm your soil. This will help prevent the roots from growing faster then your plant. The roots will stretch out in the new pot and stunt the growth of the plant. Once the roots are comfortable your plant will grow once again.
It is also a good idea to put something in the bottom of your pot. If you put a small amount of packing peanuts in the bottom the roots will find them and cling to them instead of the bottom of the pot. This allows the plant to grow quickly. Once the roots have taken hold your plant will begin to bloom and grow once again.
Fill the pot about 1/3 of the way full with fresh soil. Mix in any fertilizer that your plant is used to. Some plants will require specific soil types or fertilizers. We use gardenguides.com to see what fertilizer works best.
You will want the plant to come close to the rim without spilling over. Leave a small amount of room, about 1/4 of an inch, from the original soil and the top of the pot. Gently break up the roots and soil. This is very important if your plants are root-bound. This allows the roots to start growing again. If you have other plants to add you can do that now. Make sure to leave room between each plant for the roots to grow.
Add soil around each plant and pat it down gently. The soil does not have to be packed tight. A little bit of flexibility is good for the roots. You may want to wet the soil now as well with small amounts of water.
Finish adding your plants and add fresh soil around the top of the pot. This is also a great time to trim off dead or broken stems and flowers.
Your plant is now ready for a touch more water and a nice warm place in the sunlight. To see our series of tips on house plant care go here.