[willnbirdie]

Hi

Have 3 cucumber plants in my greenhouse.

We have had a few cucumbers off them but my problem is both the leaves and the cucumbers are going yellow.  Not all of the female flowers set fruit properly.

I have watered with tomato feed and have added some magnesium sulphate as the leaves looked very much like my tomato plants when they were suffering from magnesium defficiency.

Can anyone enlighten me as to why the cucumbers are going yellow or is it as I am guessing that due to rubbish weather my greenhouse has not be hot and humid enough for them.  Have already decided that next year I will put the cucumbers in another corner of the g/h which gets more direct sun.

cheers

willnbirdie

[Trillium]

The yellowing of leaves can be due to a number of nutrient deficiencies so I'd suggest a good all purpose fertilizer rather than a specific which is too high in something else for another plant.
Also, if the cukes go yellow, it could be that they're already too old and going to seed, which means the whole plant has accomplished its purpose and is shutting down. Lack of adequate water will help this along. Cukes need a lot of water per day to maintain proper growth and also regular picking of the cukes so the plant is tricked into growing more.
Try adding more water per day and pick off those cukes, and see if you have any more luck this year, which could be doubtful considering how late in the season it is.