I have what I think must be a perennial Helianthus flowering atm in a
narrow border bounded by a lawn, but I have to keep digging out
spreading roots every spring or it would muscle everything else out. It
either just arrived or was there when we moved in as I don't recall ever
planting one and it's not really in the best place. The flowers are
cheery though and the stems stand up well and don't need staking, so
every year I forgive it until the following spring.

Are there any tallish (4- 5ft) Heliopsis or Helianthus varieties, or
something similar, with pale lemon flowers I could plant elsewhere that
wouldn't try and take over the entire bed? I want an idea for a mainly
sunny position at the back of another border.
--
Sue