How to Properly Repot Houseplants

All plant-lovers must at some time confront the question: When and how should you repot a plant? Many of us immediately repot a container plant when we bring it home. Sometimes it’s because we think we should, or because we have a more attractive container to put it in, or because it actually needs to be repotted — at least we think it does. But does it?

Newly purchased plants do not automatically need to be repotted, and if your plant is in bloom, repotting should definitely be postponed until after it finishes blooming. You won’t kill your plant by repotting it, but you won’t help it, either.

Repotting is normally reserved for a plant that has outgrown its pot and has become potbound or rootbound, a condition where the roots have filled the pot and have begun to circle it. Some plants become so rootbound that roots begin to emerge from the bottom of the pot. And some are so rootbound that water can no longer penetrate into the matted roots. In these cases, the plant should be repotted, or at least its roots should be pruned.

But before you reach for a new pot, keep a few things in mind.

First, for some plants, such as epiphytic orchids, having roots emerging to take moisture from the air is normal, not to mention essential. These plants do not need to be repotted until the bark in which they are planted decomposes so much that it resembles soil more than bark.

Second, some plants like to be somewhat potbound and make excellent houseplants for that reason. They even flower best when their roots are bound.

Obviously, knowing each plant’s personal preferences would help. This information is available in gardening books, on the Internet or by calling your local botanical garden.

If your plant is in bloom, delay repotting until it finishes. Even then, many plants prefer a rest period. And some require rest to bloom. For plants that need a rest period, repotting should be done after the rest period because repotting stimulates growth. For most houseplants, a good time to repot is late winter, just before spring growth begins.

Picking a new container brings both size and suitability into the decision-making.

The size of the container is far more important than most people realize. Generally, you should select a pot that is only one size larger than the current container. This keeps the plant from becoming overgrown and too large to manage. If the plant is already in the largest pot that you can handle, or you just want to keep it in its current pot, you will need to prune the plant’s roots, as explained below.

The container itself can be almost anything, even an old shoe. Just make sure that it has drainage holes in the bottom (unless, of course, you’re repotting a bog plant or a water plant). You can still use a container that lacks drainage holes by using another pot that fits inside it, provided that the pot with the plant in it has drainage holes. When watering, remove the plant to an area where the pot can drain properly before returning it to its decorative container.

If reusing a pot, clean it, then sterilize it with a mixture of one part chlorine bleach to nine parts water; rinse thoroughly.

For the right potting soil, look to your neighborhood garden center. Most of these stores carry a variety of potting mixes, including specialty mixes for such plants as epiphytic orchids, African violets or cacti and succulents.

You also can mix your own soil if you know your plant’s needs and preferences.

When removing a plant from an old container, use something like a waterproof dropcloth to contain the mess. Lay the pot on its side. Tap on the bottom of the pot, then grasp the pot with one hand and the stem of the plant with the other, and gently pull the plant from the pot. If gentle pressure doesn’t remove it, carefully slide a long-bladed knife down the side of the pot, and slide it around the sides of the pot until the plant is free. A long, thin knife with a serrated blade works well for this.

If roots are tangled, gently untangle them. You may need to prune some of the longer ones, or you may want to prune the roots back to control the plant’s size and keep it in its current pot. If so, a pair of sharp pruning shears works well.

Sometimes the roots are so matted that detangling is impossible.

To free the roots, use a sharp knife to slice an inch or so from all sides of the root ball.

Finally, it’s time to put the plant in its new home.

If the new container is deeper than the old, or if you’ve pruned some roots, add enough soil to the bottom of the container so that the soil level for the plant is unchanged.

Then, add soil around the sides, watering as you go to prevent air spaces.