[Geordie]

Following yesterdays torrential rain and floods up here in the north east I have I noticed that the flood water has washed soil into the planting hole on every single leek I have planted.

The leeks are fine; it's just that every hole is completely filled in!

Will this reduce the eventual size of my leeks?

[Yorkie]

Shouldn't think it will make too much difference unless you were trying to grow show leeks.

[Plot74]

The reason to plant them in holes is to blanch them, so no it will not affect the growth. In normal weather conditions the holes would get filled in when you water them . With all the rain we have had just means the holes have got filled in sooner.
Like you I am in the north east mine have had the same but are doing well above ground level.
John

[JayG]

Another advantage of dibbed hole planting is that in theory the leek will have grown too tall by the time the hole fills in to trap soil between the leaf joints, thereby avoiding "gritty" leeks.

As long as your leeks weren't so small that the soil almost buried them you should still be OK though.