I am a novice gardener but have recently invested a lot (for me) of time and money in my garden for the first time in years and I need to look after it. I have established and new evergreen and deciduous shrubs and containers too. I have just got the hand of watering (don't laugh) and now it's occurring to me that maybe I should be feeding. What do I feed with? hopefully you will tell me that there is some liquid feed I can add to the water as I don't understand mulching. The same feed for the whole garden? And is it every six weeks?