How do you know that a plant needs to be put in a new pot? Some container grown plants can be left in the same pot for years, while others need to be repotted every three or four years. Plants might need a new container because they have grown so many roots that there is no room for water and soil. Other plants can need repotting not because there are too many roots, but because the roots have dried up or rotted. Here are a few general guidelines for repotting indoor or outdoor plants.
Some other reasons that you might want to repot a plant are:
If a plant is growing so top-heavy that it repeatedly falls over, it’s time to transplant into a larger, heavier pot. Ceramic containers are perfect for top-heavy plants as long as they aren’t going to remain outside during the winter months.
If a plant is happy, but the proportions of the plant to the pot look off, you can either transplant to a slightly larger container or place the current pot inside of a larger container, propping it up to be even with the top edge.
If you’d like to encourage a plant to grow larger, step it up to the next sized pot so that it has more room to stretch its roots. Plants that have their roots constricted won’t grow as large.
Plants that have been repeatedly fertilized with synthetic fertilizers might begin to suffer because of the salt build-up in the soil. Such plants should have some of the old potting mix washed off of their roots because placing it in with new potting media. If you want to place the plant back in the same container, wash it well if it’s plastic, and soak it for a few hours in a tub of water if the pot is clay. Scrub the white signs of salt build-up off of the inside and outside of the container.
If you’re worried that a plant has been in a smaller pot for too long, but you don’t want to increase the pot size, you can tip the plant out, pull some old soil away from the roots, and repot it in the same container with new potting mix. Top-dressing such plants with earthworm castings (available in bags in the store) can also help keep the soil alive.