I'd believe the RHS rather than Morrison's. Unfortunately if it needs bog garden conditions it isn't going to do well in a dry shady border. Not only will it get anything up to 2.5 metres in height it can also reach a metre in diameter so you need a lot of room for.

Oh dear, not a good buy then. I have a place in the garden where the soil doesn't usually dry out, so I'll try it there. Thank you for the advice MG.

Also needs staking as it does tend to flop all over the place. If you want an Aruncus which does grow to 2 feet maximum then go for Aruncus aesthusifolius, much better behaved.

Yup

I posted a photo of this in flower a few days ago.

Mine grows in a border which only receives the sun in the early morning. The soil is moisture retentive rather than wet, but the aruncus seems happy enough, having grown there for twelve years now. It has never been watered

YNow you've got the plant anyway ou could try sprinkling some gel crystals into the planting hole and remembering to water. This has worked for me but haven't tried it with aruncus.

Thank you all for your helpful suggestions. The place I have in mind for this plant is the same as where Andrewr has his aruncus so I'll plant it there (with some gel crystals as Steragram suggests), keep it watered until its settled in, and keep my fingers crossed.

Good luck!