Never be in too much of a hurry to put a plant into a larger container. Plants do not appreciate having their roots disturbed, and any damage to them will result in some check to growth. Some types of houseplants also prefer to be in small pots.
Re-potting should never simply be an annual routine. It is a job to be thought about annually, but should not actually be done unless a plant needs it. Young plants require potting on much more frequently than older ones. Once a large specimen is in a big pot, it may be better to keep it growing by re-potting into another pot of the same size, by top-dressing (see below right), or simply by additional feeding.
When re-potting is necessary
The sight of roots growing through the base of the pot is not in itself a sign that re-potting is immediately necessary. If you have been watering the plants through a capillary mat, or have placed the pot in a cache-pot, some roots will inevitably have grown through the base to seek the water.
If you are in doubt, knock the plant out of its pot. To remove the root-ball easily, invert the pot and knock the rim on a hard surface while supporting the plant and compost (potting soil) with your hand. It is normal for a few roots to run around the inside of the pot, but if there is also a solid mass of roots it is time to pot on. There are several ways to re-pot a plant, but the 2 methods described here are among the best
1 Prepare the new pot as in step 1 of the Traditional Method if you are using a clay pot. However, if you are using a plastic pot and you intend to use a capillary watering mat, do not cover the drainage hole at all.
WHEN TO RE-POT
A mass of thick roots growing through the bottom of the pot (top) is an indication that it is time to move the plant into a larger one. Equally, a mass of roots curled around the edge of the pot (above) is a sign that it is time for a larger container.
The vast majority of plants on sale are grown in plastic pots, which are inexpensive, light and remain largely free of algae. Plastic pots do become brittle with age, however, and even a slight knock can break them, whereas a clay pot will not break unless you actually drop it on a hard surface.
1. Once plants are in large pots, perhaps 25-30 cm (10-12 in) in diameter, continual potting on into a larger pot may not be practical. Try removing the top few centimetres (inches) of compost (potting soil), loosening it first with a small hand fork. Replace this with fresh potting compost of the same type. This, plus regular feeding, will enable most plants to be grown in the same pot for many years.
2. Put in a little dampened compost (potting soil). Insert the existing pot (or an empty one of the same size), ensuring that the soil level will be 12 mm/1/2 in below the top of the new pot when filled.
3. Pack more compost firmly between the inner and outer pots, pressing it down gently with your fingers. This will create a mould when you remove the inner pot.
4. Remove the inner pot, then take the plant from its original container and place it in the hole formed in the centre of the new compost. Gently firm the compost around the root-ball, and water thoroughly.
1. Prepare a pot that is either 1 or 2. sizes larger than the original and, if the pot is a clay one, cover the drainage hole with pieces of broken pot or a few pieces of chipped hark.
2. Water the Plant to he re-potted, and leave it for a few minutes. Remove the root-ball from the old pot, either by pulling gently on the plant, or by inverting the pot and tapping the rim on a hard surface.
3. Place a little compost (potting soil) in the base of the new pot, then position the root-ball so that it is at the correct height. If it sits too low or too high, adjust the amount of compost in the base.
4. Trickle more compost around the sides, turning the pot as you work. It is a good idea to use the same kind of compost -peat- (peat-moss) or loam-based — as used in the original pot.
5. Gently firm the compost with your fingers. Make sure that there is a gap of about 12 mm-2.5 cm (1/2-1 in) between the top of the compost and the rim of the pot, to allow for watering. Water thoroughly.
POTTING ON, POTTING UP, RE-POTTING
Potting up is what happens the first time a seedling or cutting is given its own individual pot.
Potting on is the action of re-planting the root-hall in a larger pot.
Re-potting is sometimes taken to mean replacing the plant in a pot of the same size, but with the bulk of the compost replaced, if the plant cannot he moved into a larger pot.