When Roots Go to Pot, It’s Time to Repot Plant : Transplanting: How to recognize when plants are root-bound. A seven-step technique for transferring them to larger pots.

One of the most feared, yet one of the easiest aspects of indoor gardening is the common transplant operation.

Transplanting, or repotting, becomes necessary when your plant is root-bound and just sits there, failing to grow. One sign that your plant is root-bound is if water rushes right through the pot and out the bottom when you water, but the best indication that a plant needs to be repotted is the sight of roots coming through the drainage hole at the bottom of the pot.

Sometimes, if there is no drainage hole or the roots are packed so tight that they can’t grow out the bottom hole, it will be necessary to remove the plant from its pot and check the roots. Lift the pot, turn it upside down, and lightly tap one of its edges against a table or a sink. The plant should slide right out, its roots and soil contoured to the pot structure.

If the roots are obviously overcrowded--that is, if you can see lots of roots and just a little soil--it’s time to put the plant into a larger pot.

There’s no need to call a tree surgeon to perform this simple task. Just remember these seven basic steps and, in most cases, your plant will come through the operation as good as new:

1--First, get a new pot, not less than 2 inches or more than 4 inches in diameter larger than the plant’s old home.

Make sure that the new pot is made out of terra cotta (red clay), which, being more porous than plastic, permits more air to get to the roots and also helps prevent overwatering, the number-one killer of plants.

2--Place a clay pot chip over the drainage hole in the new pot so that water and soil won’t run out too quickly. If you’re repotting into a container without drainage holes, be sure to fill he container at least one-fourth of the way up with clay chips or pebbles. This will absorb and evaporate water so your plant won’t get root rot.

3--Add fresh, commercial potting mix into the new pot until it’s about one-third full. Since overwatering is such a danger to your indoor plants, it’s important that they be potted in a light, airy, sterilized potting mix. Do not use ordinary garden soil to pot your houseplants--it’s way too dense and might harbor any number of plant-eating pests.

You an make your own potting mix by combining one-third garden loam, one-third peat moss and one-third perlite and then baking the mixture in a 450-degree oven for a couple of hours to sterilize it, but it’s a whole lot easier to buy a bag at your local nursery or garden center.

If you’re working with cactus and succulents, get a cactus mix which is a more sandy soil, and for orchids and bromeliads use fir bark or osmunda, which provides maximum drainage.

4--Take the plant out of the old pot and loosen the soil around the roots, removing some of the old soil. Work quickly, so you don’t expose the roots to the air any longer than is absolutely necessary.

By removing the soil with a gentle massage at the bottom of the roots and extending them, you’ll be giving the roots a huge head start into their new growth pattern. And remember, the quicker the roots grow, the faster they’ll fill up the new pot and be ready to send up new energy to the plant.

5--Place the plant into its new container, adding or subtracting fresh soil below the plant until it’s at a desirable, decorative height.

6--Now start adding soil around the plant, packing it down tightly until the soil is level, and about one-half inch below the top of the pot.

7--Water the newly potted plant thoroughly. For best results, add some vitamin B-1 solution, available at most nurseries and garden centers, to the water. This will help prevent transplant shock.

Very often a plant, whether it be a large tree in a corner or a smaller plant on a table top is aesthetically perfect for the spot that it is in, so you won’t want to transplant it. However, you should refertilize it every two or three years by “topping the soil,” a very simple procedure: Scoop out as much of the old soil as you can without disturbing the roots.

This is easier to do when the soil is slightly moist. When scooping out the old soil, always work from the outer rim of the pot toward the center to protect the roots. Now replace the old soil that you’ve removed with fresh sterilized potting mix. Pack it down as firmly as possible, leaving a few inches at the top of the pot (usually the width of the rim) so that the water will be absorbed and won’t run over the sides.

Whether you repot or simply top the soil, your plant will appreciate this thoughtful gesture and will probably sprout a few new leaves or grow a few inches in a very short time to show you how much. Happy growing!