Pruning - will I kill them?

[Gentleness]

What with one thing and another, I've not put enough time into the garden this year and now I've hit the 2nd trimester and the building work is finished, I'm looking out in horror. Everything needs a good prune, weeding, you name it...

My worries are that I will wreck plants that need to limp on for a bit longer till i can think through how I want this garden to look and work. I don't want to look out on a mess all winter!

Can anyone advise me on how harshly I can prune the following, given I am a novice at best:

common sage - huge bush in front garden, old old wood in the middle, lots of new growth, lovely flowers which I didn't dehead...

lavender - no idea which sort, except not butterfly

peony - really leggy, didn't think the tubers I could see were anything living so the shortlived but bright flowers were a bit of a shock!

spirea (I think) - arching quite delicate leaves with not v abundant white tiny flowers earlier in summer

evergreen one I think of as red robin - green leaves with new ones red.

I only know about the lavender because I have loads of them. Topiary shears are the best thing to use so you can get a nice shape. Don't cut into the wood because it might not grow back, just trim back as far as you want in the green bit.

Having said that, I tried to kill a couple of too-large lavender plants by hacking them right back to a tiny stump and they both came back.

I think you can take cuttings of lavender fairly easily so if it's gone leggy or is getting too big then you could save a few of the clippings and stick them in a pot to see if they root. They also seed around quite easily which is why I have loads of them.

Sage - hang on till spring, and then take it back hard, to wherever you see new growth appearing in a place that you think is right.

Peony - do you mean a tree peony? If so, take one or two of your oldest stems right out at the bottom, so that new stems will grow, and it won't get too congested.

Lavender - as eau rouge said.

Spirea - it depends on the variety, and whether it flowers on the previous year's growth or the current year's growth.

HTH