In cases such as the one just described in which a plant is definitely ailing as a result of being too closely confined, it is necessary to repot that individual plant. As a rule, however, it is more efficient if you are growing a good number of house plants to arrange to repot all those plants that look as though they are going to need it at one time. The best season to do this job is in the spring before the plants go outside.
1) Arrange the plants you are going to repot on a table in order of pot size so that you work from the largest to the smallest. You do this so that as a pot is emptied it is ready to receive the plant from the next smallest pot, and so on down the line. At the same time set out your potting soil, plant food, charcoal, gravel and crocking. A wooden slat or potting stick which can be used to settle the soil is also useful. If you are going to use any new pots, have them soaking in water from the previous day to get rid of any impurities and to make sure that they won’t immediately absorb a large part of the water meant for the plant. (You will obviously have to have at least one new pot to take the plant from the biggest one in use up to this time.) Just-used pots should be thoroughly scrubbed as they are emptied, before a new plant is set into them.
2) As you work along, set a two-inch layer of crocking and gravel in the largest pots to act as drainage material. All but the smallest pots should have at least a few pieces of crocking in the bottom. In all pots which do not have a drainage hole, this is especially important. These pots should also have on top of the drainage material a layer of peat humus and a generous sprinkling of charcoal to keep the soil from going sour. Both peat and charcoal are available commercially at the same stores your other garden supplies can be bought, and they are both inexpensive and easy to work with.
3) Fill the pot into which you are transferring the plant about a quarter to a third of the way up with potting soil, then turn the plant out of the old pot. If there are pieces of crocking sticking to the roots remove them and shake off any loose soil clinging to the ball. Place the ball in the center of the new pot and, still holding on to it, sift in soil around the roots. The potting stick is useful here to make sure that there are no gaps in the soil and that it is packed in firmly. Remember to allow enough space at the top for watering. When the plant is firmly in place, give it a thorough watering. It is also wise at this time to administer some plant food. Follow the same procedure with each plant until you come to the last one. Repotting is a helpful and necessary procedure in keeping up the health of your house plants. It mustn’t be overdone, however. Potting a plant in a pot which is too big for it can be just as disastrous as letting it stay in a pot too small. An overly large pot holds water for too long and can rot the roots of the small plant unable to use the moisture.
Top dressing. With extra large plants and extremely sensitive ones which will not take repotting you can employ a substitute remedy known as top dressing. Here you scratch off the surface soil down as far as you can go without exposing the roots. Then refill with an enriched potting soil and add a strong diet of plant food. The enriched soil will pass food down to the roots and if the plant has been suffering from lack of nutriment it will revive.