Perennial border establishing

Helen Bang · April 2022

I am developing a border on a sloping garden. It looks wonderful in the Spring with lots of bulbs, pulmonarias, later aquilegias and alliums. It's edged with achemilla mollis. Later there are verbascums, but once these start to fade none of the late summer plants I have planted seem to thrive. (Salvias, asters, heleniums, rudbeckias.) Many don't come back after the winter or if they do never 'fill out'. We're in central Scotland and when we don't get rain the soil dries out fast. It's very stony although I've added lots of compost. I'd like plants that grow to a metre or more in height, ideally in 'hot colours' as I have pink, white and blues in the front garden. I have lots of dahlias in other beds, but I don't want to put these into the border as they'll need lifting and it will disturb everything else planted. i've got crocosmias elsewhere doing well but they do rather take over. Any suggestions? Thank you!

BlueBirder · April 2022

Aside from being stony, do you know what type of soil you have (clay, peat, loam etc)? How much sun does it get?

Suggestions for hot colour perennials which can cope OK in dry conditions -

Helianthemum can be drought tolerant when established e.g. Ben Hope.
Coreopsis can cope with dry conditions - Limerock Ruby is red.
Echinacea can cope with most soils and there are plenty of hot coloured ones.
Achillea e.g. Red Velvet, Terracotta, Walther Funcke
Knautia macedonica
Agastache e.g. Summer Sunset
Potentilla e.g. Monarch's Velvet, Gibson's Scarlet.
Euphorbia griffithii
Cetranthus ruber
Anthemis tinctoria

Others will probably be able to give you more advice

JennyJ · April 2022

Are your salvias the shrubby ones or the herbaceous types? The shrubby ones do well in my dry stony conditions. Maybe try Nachtvlinder (small deep purple flowers but lots of them) - it is shrubby and not as tall as you want (mine get to maybe 60 to 70 cm) but spreads at ground level like a perennial and is tough.

Of the asters, the one that really thrives here is "Little Carlow" (mauve). Helianthus "Lemon Queen" does well too and looks nice with the aster but is taller , maybe 1.5 to 1.75m here but more in richer wetter conditions.

Fairygirl · April 2022

It'll be clay.
You'd need to add organic matter to stop it cracking. It rarely happens here, but we have had more long term dry spells.
The only salvia that's hardy here is S. caradonna. Forget the others unless you want to over winter or take cuttings.
Many rudbeckias aren't hardy here either.

The Asters and Heleniums are though, so it's odd that you're finding they struggle. Many perennials are short lived though, so you need to divide them every so often to keep them healthy. Achilleas, Liatrus, Lychnis, Kniphofias and some Agastaches will also be fine, but it sounds as if you need to beef up the soil a bit to make it more hospitable.

Perennial border establishing

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