You forgot to say which plant you're asking about, Guest!

Well I was also wondering that- from a Buddleia black knight? I tried removing some brances, dipping in rooting hormone and putting straight into the garden but none of them took!

When did you try this, Novice? Early spring is good, but probably not 'til near the end of the frosty part. 'Zonies like me do it in December, but we hardly get any frost here in Phoenix. Summertime is a definite non-starter, and they might get heaved out if started in the fall in Surrey, though pots buried in a cold frame might work.

Ah! That could have been the problem Tugbrethil! I quickly grabbed some on moving day- so beginning Aug! Maybe I'll just get some seeds and start from scratch!

They won't come true from seed, Novice. To thoroughly hybridized. On the other hand, you could have your own personal variety!