By Sjw
gloucestershire,
United Kingdom 
I have forget me nots that have now gone over, do I pull them all up or just trim back if I want them to return next year.
30 May, 2018
Answers
They look lovely in that border, but yes, I pull them up and always have plenty the following year.
30 May, 2018
if you want to see if any have formed seeds for about a week then pull them up. you will then get self sown jobs for next year and beyond.
I grew these 8 yrs ago and still get plants coming up and I pull them just as they finish flowering.
30 May, 2018