You need to check the roots. If you see roots growing out of the bottom drainage holes, you really need to do something right away. You can also tip the plant out of the pot and inspect the roots. If larger ones are visible out to the outside edges of the soil ball, you need to do something soon. If the roots are so dense you can barely see any soil, you need to to do something right now.

The other way to tell is to look and decide if you think the plant looks top heavy and unbalanced or if the plant is tending to tip over due to top being heavier than the bottom.

The "something" is either root prune or repot. Root trimming involves teasing out the roots from the soil and trimming about 1/3 away, then replanting with fresh soil into the same pot. Best done in the spring.

Repotting is usually done into the next size up pot, root bound plants may need some mild root trimming before repotting.

Here is a link that might be useful: Repotting

Repotting can occur indefinitely - most nurseries/growers that sell containerized plants do this as a matter of course, as do plain ole gardening folk that grow a lot of plants in containers. The older a plant gets and the larger the container it is in, the less often this process needs to be done, although the occasional root pruning and refreshing of planting media is ongoing. For smaller plants, you want to make sure you have sufficient space for additional root growth and enough loose medium to hold and retain moisture without the water running straight through or just down the sides of the container.

If you are forced by size or inconvenient timing to delay potting up and the container dries out excessively, submerging it in a tub of water until it sinks and you see no more air bubbles will help.

Since I grow several bonsai, I am a big fan of root pruning, an essential task in their maintenance. I've been root pruning just about all of my other plants (permanent container plants) for many years...especially once I've found the perfect container or simply do not want to move a plant to a larger size.

And the bad news is - some plants actually need attention twice a year. If you find that the rate of growth is such that the roots are escaping by summer after you repotted in spring you may need to use a bigger pot, ease back on the feeding, reduce the amount of leafiness as well as the quantity of roots, - and do it more often (like autumn,just before rain and well before the first hard frosts). The usual response is more new shoots which need to harden off before winter.

Two I find that need this frequency are Lonicera (honeysuckle) and Coprosma kirkii. It's the tightly wound web of roots that clearly show the shape of the pot which give them away.

There are some situations where you may want the plant to become pot bound. Some succulents will put out offshoots which are easy to propagate when pot bound. Some Sansevieria are more prone to blossom when pot bound.

Clivias, too. I'm always amused by the message about some species being 'pot-breakers'. Keeps me going when I do, finally, struggle the Clivia clump from its weirdly distorted pot!

Geraniums also love to be root bound! My geraniums bloom ALL YEAR for this and I put them in a cold frame during the winter and they still bloom! I have never lost a geranium yet and my husband can't stand me cause I have learned how to propagate them. I now have more than 180 plants taking up my carport.

Hi, I have another question along this same subject. I was given a house plant vine and the pot does not have any holes in it. The pot is beautiful and I like that it doesn't leak all over my shelf. I've had the plant for a year now and it is still growing and the leaves look healthy, etc. What do I need to do to make sure it stays healthy?

what size pot do I need for a 12 foot shefelra indoor plant.It is in a 14 inch high by 16 inch wide pot know nd is startign to tip over.