Cucumber leaf yellowing

[Containergardener]

I was given two plants, this plant has a yellowing leaf and not sure why. Same conditions as other plant. Any thoughts?

Went to edit to add pic then delivery driver appeared (very very chatty one)

[WendyC]

Could be a number of things. If it is just the lower leaf, I wouldn't worry as they tend to lose them as they grow anyway. Could be scorch through a window, or wind burn. Doesn't look like a disease or pest. I think you'd have to be really unlucky to get red spider mite this early in the season.

[Potstubsdustbins]

If it has been to bright sunlight close to a window I would go with a touch of sun scold too.

[Containergardener]

Well they've been in living room away from window (no room on sill) , I will keep an eye on it, it will get lopped off otherwise .

[Marb67]

When would be a safe time to plant Marketmore outside please ?

[Martin H]

Check your frost risk. Down here I'm going to have to wait at least another week. Here's a good page: Metcheck.com - Hang On.. Let's find your location first...