Camellias are one of the few winter flowering shrubs that will respond to pruning if necessary. It is important to realise that the flower buds for the Camellia are formed in early summer, ready to flower in late autumn or winter a few months hence. Any pruning carried out should be done right after flowering, in order to allow the shrub enough time to produce new shoots and flower buds.
Late pruning will inevitably result in a winter season with few or even no flowers. Late pruning of Camellias and other winter flowering shubs is one of the main causes poor or no flowers.
The shrub needs time through the spring and summer growing season to firstly produce new shoots and then produce the flower buds on those shoots ready for winter flowering. Flowers don't simply happen. They are a result of flower buds sometimes produced several months before actual flowering.
The most basic form of pruning camellias is simply dead-heading the faded blooms which simply make the shrub look untidy. Dead-heading does not prolong flowering as such, for as explained earlier, the flower buds will have been formed long ago. However, with single flowered varieties in particular, it can prevent seed setting. It takes energy to form seeds and this will have to be diverted from the general growth if the shrub.
The image shows quite clearly, a typical cluster of rounded flowerbuds as the plant does into winter. these buds would have been produced through July/august. leaf buds would normally be elongated and pointed.
Pruning is generally carried out in order to maintain a compact shape to the camellia. Pruning is only necessary for this reason. If you are happy with a lax, open habit maintained by some varieties, then no need to prune for this reason.
pruning Camellias is not rocket science. You can simply trim off any elongated shoots that you feel will eventually spoil the shape of the shrub. Cut back the 'offending' twigs with a pair of secateurs to just above a pair of health buds further down the stem. Do not cut back too far, unless you really need to head the size back.
If your camellia has been neglected, or if you really want to re-start with a smaller shrub, camellias respond quite well to pruning hard or rejuvenation pruning. Do this type of pruning as early in the spring as possible, and be prepared for some robust shoots to emerge. these in turn may need shortening in order to start a bushy framework once again.
The camellias response and happiness with being pruned, also makes for good Container plant specimens. Formative clipping - with secateurs - will allow you to train a pyramid shape - though not as formal as attained by training Bay trees.
The single most important fact to bear in mind, is that if you want flowers the following winter, then your pruning needs to be undertaken immediately after flowering. If you are prepared to sacrifice flowers for a year or so, then the Camellia can be pruned a little later, but before the summer sets in proper.