[Mazzie]

After finding a family of baby wrens living in the buddleia in my garden ive been thinking about putting a large shrub or two in the nature area on the lottie to bring more birds and butterflys in.

I was originally thinking something with a little less triffid capability as mine are over 9 foot after two years neglect, but ive found a self seeded buddleia growing happily next to my squash patch today. 

Would it be a silly idea to keep such a could be crazy plant on the lottie?  I really cant decide.

[Trillium]

If it's not in your way you enjoy it, why not? Never hurts to attract pollinating insects with flowers. I have borage all over the place for them.

[mumofstig]

Others may complain because as you've found..........they seed themselves readily.
Depends which kind of plot you have. I don't suppose the so-called 'garden plot' sites would object but on an open-style allotment site they may not be welcomed

[Aunt Sally]

Would it be a silly idea to keep such a could be crazy plant on the lottie?  I really cant decide.

In my opinion it would be a bad idea on an allotment. 

YOU would have to be totally responsible for keeping it pruned each year (for it's entire lifetime) and for removing any of its progeny.  Could you promise that ?

[arugula]

I would agree it isn't a good idea, in that Buddleia is a very vigorous growing shrub.

[TerryB]

Given all the weeds you get on an allotment, a few more from a plant that looks great and attracts butterflies, wouldn't both me. If fact I'd welcome it.
Ask the other plot holders but do keep it under control.