[stephent]

My sweetcorn are really motoring.  They are around 4ft tall and very sturdy and thick. I have only spotted a few cobs though

My neighbours plants are much smaller than mine and she has cobs. Its as though the plant is using all its energy to grow and not form cobs?

[Auntiemogs]

I don't have the answer (sorry) but it may be useful if you tell us if/what you have been feeding them. 

[stephent]

only fed them twice with some B&Q cheapo liquid feed

[mumofstig]

There is a lot of height variation between the different varieties
Have you got tassels at the top, the cobs don't usually start to show until the tassels start to open.

ASk your neighbour which variety she is growing if you would prefer a shorter variety next year 

[stephent]

I am growing F1's

Went down the lotty tonight and noticed a few more silks.

Maybe i am just being to impatient. lol.

[Yorkie]

F1 isn't a variety; it means that the seeds came from the breeding of specifically selected parent plants, and that the seeds for subsequent years won't come true.

Do you know what the actual name of the sweetcorn variety is?

[wil4025]

Ive found a trick by brushing your hand at the top of each plant.