The Editor's Tutorial

.Potting On

   Every four or five weeks the plants are potted on thus ensuring that the roots are always growing into fresh compost.  The actual frequency will be dictated by vigour.
The new pot will be about 15% larger.
The compost is Scotts Levington M3.
Note:
In addition to this page the tutorial lists 3 other stages :
Starting, First Potting, Final Potting.  In some cases this routine may be reduced.

Primrose

Once the roots have reached the sides of the pot it is time to allow more space.  Do not wait until the plant becomes pot-bound.

As always the compost is pre-mixed, adding sufficient water to make it cling together but not so much that it becomes sodden.  Using tepid water will bring the compost up to temperature.
Here on the South Coast tap water contains an element of lime, this suits begonias. 

Having ensured that the plant is well watered ease it out of it's pot and place this pot inside the new, larger one to act as a former.  Fill between the two with compost.      

The new pre-moistened compost  is compacted reasonably firmly by pressing down the smaller pot .

With the plant in it's new pot add a little more compost to the top then press down around the sides.
Do not fill to the brim, leave space for a top dressing that will be applied later.
Finally tap the pot against the bench to settle the compost.
No more watering should be required for two or three days.     

Sometimes the stem will grow from the side of a tuber.
When potting on take this opportunity to centralise the stem to the middle of the new pot. 

        THE NEXT STAGE