[Yabba]

That's a new one on me, might have to google it just for the entertainment value

¥

[Mark-S]

may i suggest you think about the natural life cycle of plants........they grow, they pollinate, they fertilise, they produce seed, the seed FALLS to the ground is is worked into the soil by whatever means possible.....they do not decide which way to be sown.

Similarly there is geo-tropism to consider.

I could get all technical, however the simple answer is - IT DOESNT MATTER

[Yabba]

may i suggest you think about the natural life cycle of plants........they grow, they pollinate, they fertilise, they produce seed, the seed FALLS to the ground is is worked into the soil by whatever means possible.....they do not decide which way to be sown.

Don't be daft, they'll fall sharp side down

¥

[sunshineband]

Geotropism -- yes that's what i was talking about 

[Ivah]

Naturally Broad Beans would end up on their sides most of the time and many would rot but the plant isn't "expecting" 100% success or it wouldn't produce so much seed, but we are. Gardeners' experience over the years has proved that on edge is more successful. With the scar vertical you would have to be able to recognise which end of the scar was root to make it as easy as possible for the plant to get started or shoot and root would be crossing or trying to spin the seed, as most of us start them in rootrainers movement is somewhat constricted so this is tricky. Similarly scar up gives the root a fairly awkward route down and as this emerges first it is more important. So on edge scar down makes logical sense. On another forum someone has done the science and measured speed and evenness of germination and confirmed this. I doubt it makes as much difference in open ground. 

[wyandotty]

Thank you everyone for your replies, when I come to sow my runners I am going to start some with scar up and some with it down and see what happens

[GrannieAnnie]

Even runners that I've planted upside down will grow downwards for a bit, then realise they are going the wrong way and turn around, they just come up a bit after the others!   

[Christine]

Yep GrannieAnnie, that sounds about like my experience. Like but I never thought there was a right way and a wrong way to plant bean seeds. Good thing it doesn't apply to peas!