"Rule of Thumb" : Prune most shrubs soon after blooming.
As for pruning techniques.....go to You tube website and type in the shrub you want to prune.....good videos on pruning etc.

google: rejuvenation pruning of flowering shrubs ...

both fit within that definition ...

a youtube would be great ... but it doesnt have to be of lilac or Vs ...

ken

If you are just removing dead or dying leaves it doesn't matter when you do it and it won't affect the shrub's growth habit. 'Pruning' refers to the removal of woody stems. You need to research your shrubs individually. Some shrubs flower on new wood i.e. made that year, and some flower on old wood, i.e. made the previous year.

BTW Echiums are not shrubs. Some are annuals and some perennials but all are herbaceous.

Just to clarify - 'rejuvenation' pruning is not intended to be a routine practice. It is intended to rejuvenate or bring back into shape a mature and overgrown shrub. Not all shrubs are served by this practice anyway.

If woody plants are maintained carefully from the start, pruning as needed, rejuvenation pruning may never be required. And to expand on the floral's "old wood/new wood" concept, there is a rough rule of thumb you can follow for any flowering shrub: if it blooms before June, prune immediately after bloom. These tend to be shrubs that produce flowers on previous year's growth so pruning as soon after bloom time as possible will allow sufficient growth and bud development for the following season

So in the case of the lilac just cut under the seed head since the bush is under a year old is it necessary? Because to I planted it in last October?will not deadheading stunt growth and next years bloom? I should just remove the diseased leaves. Can anyone direct me to site that explains the basics of pruning and deadheading especially with regards to leaves. Sorry for the silly questions I'm a newbie and don't want to lose my plants

Dead heading will not stunt growth and doesn't really count as pruning. Just be careful on lilac that you take off only the old flower head and not the two buds immediately below it. That would affect next year's flowers. But dead heading lilac is really only aesthetic. It will manage quite well without it.

Also do not feel you need to spend time removing leaves unless they really offend you. Dead leaves fall of their own accord. If they are still so well attached you have to pull them off they are still alive and feeding the plant.