[tooo many seeds]

my cucumber is about a foot high with 8 flowers on it,its in a pot at the moment and i will move it to a grow bag soon in the greenhouse,how big do they get before the first cuc appears.

[Rangerkris]

If you have flowers, the cucumbers wont be long.

[prakash_mib]

If you have flowers, the cucumbers wont be long.

provided they have female flowers and beign pollinated 

[sarajane]

If your greenhouse is not heated cover them well if the temperature drops too low or you will loose them,

[compostqueen]

I think how big it grows depends on what variety it is. Some are taller and more sprawling than others