[mdjlucan]

can you put a i d on plant wen can i prune it back

[mdjlucan]

same pic

[Yorkie]

Have you ever seen flowers on it?

Have you tried crushing some leaves to see whether they have a scent?

I'm wondering whether it's a big herb or similar, but it's difficult to tell from the photo.

It looks quite woody near the bottom; I'd leave pruning it for another couple of months and I wouldn't prune hard because the plant may not regenerate from the bottom.

[Spana]

Looks a bit like artimisia.

[sunshineband]

Looks a bit like artimisia.

I does look like one of the fine leaved sorts like filifolia.

Agree with Yorkie -- don't prune into old wood as it may well not regenerate 

[mdjlucan]

yellow flower comes out on it

[gobs]

It reminds me of cotton lavender. Do you need to prune it for any particular reason? Would be better founding out first, what it was.

In my personal view, whatever it exactly was, it looks like something that might need pruning a bit later.

[Yorkie]

If it is artemisia then the pruning advice is really conflicted - whether you can prune back hard, and whether to do it in autumn (most American sites) or in spring (RHS).

That's not very helpful I'm afraid!

[gobs]

yellow flower comes out on it

It probably will be cotton lavender then. Botton flowers on top?

Leave it alone for a month yet at least.

[Yorkie]

Artemisia has yellow flowers too.

How sure are you about cotton lavender gobs?  The leaves look longer than those on the bbc's page on it.

[gobs]

Say 80 % sure? 

No, I'm not sure, just a thought. They are very varied in growing.

[Aunt Sally]

Looks a bit like artimisia.

I  agree.

I hack mine down quite hard when it overgrows it's space.

[Spana]

Looks a bit like artimisia.

I  agree.

I hack mine down quite hard

 So do i, cut mine to the ground every spring

edited to add, I also have cotton lavender and looking at the photo, the plant hasn't been cut since last summer, in which case the little pom-pom flower heads would still be showing as they stay on the plant a long time

[sunshineband]

I don't think it is cotton lavender, I still go with an artemesia

[Spana]

We have 3 spellings for the plant name here here I think Yorkie has the right one