Why do weeds grow at the bottom of the garden fence?

I am currently digging up a border around the edges of my garden, our lawn is alright, but the edges are a total mess. All the way around, at the bottom of the fences, ginormous weeds and extra long grass grows. There are nettles and huge dandelions mainly.

I'm curious, is there a reason they grow at the bottom of the fence? Is it coming through from the neighbouring gardens? The lawn currently goes all the way to the fence, the weeds aren't growing through open soil.

In digging up the border round the garden (I've currently dug up one side), I've taken up as many of those nasty weeds as I can, but is there a way I can keep them down, I will keep the border empty for a couple months before planting anything in it, so I'll be able to see if any weeds come back up, but there must be a reason they have been growing consistently at the edges of the lawn?


(The lawn actually ends just at the left of the picture, hence why there's some weeds at the side, it was a patch of soil from under a patio we took up, and weeds took over. The weeds growing up the fence looked like that round both sides of the garden! They were dreadful!)
Thanks!

 

I suspect its the birds sitting on the fence then having a poo with seeds in

Looks like you have had a mini border and the weeds find that soil next to the fence easier to grow in plus cutting the lawn you have not gone close enough to the edge to cut them down

looks like nettles to me so make sure you put gloves on

 

You might be better off spraying them with glyphosate, they'll come back from the roots if they're coming from next door.

 

They grow there because the mower cant cut then right up against the fence.
You need to get a strimmer and cut against the fence before doing the mowing.

Not many weeds can take continual mowing.

 

I agree with Pete. If you let the lawn grow you'd notice the weeds coming up other places in the garden too. You need to strim/cut back right up to the fence line.

To the left of the picture looks like bindweed, which is a pain to get rid of. Have a look here for some advice.

 

I have quite a thickly grown "bottom fence" area, loads of plants and about twice a year I go down and forage for all the weeds, the nettles are definitely sending runners from the other side of the fence, I periodically go round , it is a large field behind me and the access road to the railway tracks is directly behind the fence, tall weeds , so I try to pull the weeds away from my fence, it is the prevailing summer wind direction, so as already said it is wind borne seeds plus the birds fertilising.

 

I sprayed the nettles off in the field last year, as they only grow just either side of the fence, only one clump came back