HelixStalwart writes:

Which bushes stay and which, sadly, have to go? (Anyone in the UK will
know we folk in Scotland rarely throw anything away!)

Most roses are pretty tough plants, once they're established. Hard to
say without seeing them, but even if they lose all their leaves and
everything down to an inch above the ground they can usually come back.

How can I improve the soil?

General purpose balanced fertilizer as directed on the box. Compost
once a year is nice. Mulching is a big help keeping down the weeds
and helping it live through the winter.

How can I make any surviving roses healthier?

I'm not sure how much rain you get during the summer. If it gets dry,
or even less wet, they'd be helped by water. Aim for a total of about
1 inch of water per week, in two or three soakings, if there isn't
that much rain.

Do you have any beginners advice for me? I.e. is it the correct time
of year to put in an extra rose or should I wait till next year?

Spraying is controversial here. If the plants are otherwise healthy,
a touch of blackspot and a little insect damage now and then probably
won't hurt it. But spraying may endanger the beneficial insects that
keep the harmful insects under control, thus hooking you on expensive
chemical controls. I see why exhibitors spray all the time, but that
sounds like it's not what you're after. My philosophy is that any
rose that's too fragile to survive without frequent spraying should be
replaced. Washing the aphids off with water regularly does a lot of
good.

However my philosophy is based on the U.S. Pacific Northwest,
practically rose heaven (except for Bourbons). Your needs may be
different. See if you can get local advice.

Oh, yes, time of year. If you buy roses already potted anytime that
the ground isn't frozen is okay to plant. If you buy bareroot roses
they'll be cheaper but a little harder to get started, they want to be
planted when they're dormant in the winter.

-- Patrick
in Seattle, USDA zone 8 (but really warmer for last 20 years)