Of all the gardening tasks, repotting is my favorite. Give me a bench full of plants to repot and I’m in horticulture heaven.
Houseplants need repotting when they start to become root bound. You’ll know when this happens because roots will grow out of the drainage holes or the plant tries to push itself out of the pot. You may also notice that the soil doesn’t hold water anymore.
That’s because there’s actually no more soil; the pot is full of roots, so there’s nothing there to hold water. The interval between repotting depends on the size of the container and the speed at which the plants grow.
There’s a natural human tendency to repot into MUCH bigger pots. We figure they’re just going to keep outgrowing their pots so why not put them into a really big one now. The problem is, when a plant goes into a much bigger pot there’s too much soil for the roots.
The roots spread out, which means they don’t concentrate energy to the plant, and they tend to rot because the excess soil holds too much water. So, when it’s time to repot, choose a container that is about two inches bigger, no more.
Of course, your new pot needs drainage holes. To keep the soil from running out the holes, cover them with a coffee filter, potshard with the curved side up, or wire mesh. Before you fill the pot (unless it’s brand new) scrub any dirt away with a brush and wash the container in a solution of ten parts water to one part bleach. (Wear gloves to protect your hands from the bleach.)
You can use a commercially prepared potting mix or make your own. Many different types of potting soils line the shelves of garden centers. Some have fertilizer mixed right in and some don’t. Some are soilless and some contain soil as part of the mix. Look for a mix that contains organic matter (dried cow manure or compost, for example) and either sand or perlite (not vermiculite). The potting mix should be evenly moist before you use it.
Okay, you have your clean pot, your potting mix, and your plant. Put a small amount of potting mix in the bottom of the pot. Now, extract the plant from its old pot. Best-case scenario—it comes out easily with just a gentle tug. But you may have to turn the pot upside down, straddle the plant between your fingers, and knock the pot against a solid surface. Worst-case scenario—you have to break the pot to get the plant out.
If the plant is seriously root bound the roots will be twisting around the plant. If you repot it in that condition, the roots won’t take advantage of their new surroundings and will keep circling around. To prevent that from happening you may need to unwind and/or sever roots that encircle the plant.
Set the root ball in the middle of the pot. Hold it so that the old soil surface is one-quarter to two inches below the rim of the potting, depending on the size of the pot. Fill soil around the root ball, gently pressing the soil in with your fingers, but not packing it tightly. Don’t put any new soil on top of the root ball unless you have removed soil from there.
Now, water well until the water runs out the drainage hole. That’s all there is to it.
Want to learn more about repotting?
The following websites have more repotting tips along with pictures that illustrate the process:
The University of Illinois Extension has lots of information related to Repotting Houseplants.
Check out the weekend gardener and learn How to Repot Rootbound Plants.
The University Extension at Texas A&M University has plenty of information about Houseplants.