[Lardman]

For years I've grown in pots outside and in the main I've only had one problem - blight.

This year with my nice new greenhouse I seem to have the kiss of death ! Im plagued by greenfly and white fly, not a predator in sight. I've got slow growing tomatoes, and cordon plants that think they're determinate. Peppers that despite being 5 months old are less than 3 inches high, all the courgette seedlings have keeled over and died, and to top it all my cape gooseberry is suffering so badly it looks more like a euonymus japonica. 

This greenhouse growing lark is well hard ! I need to go back and relearn the basics, any links worth a look ?

[mumofstig]

and cordon plants that think they're determinate

No consolation I know, but I share this problem, at least!
If we had had a'normal' spring I don't think you would have these problems, temperatures have been up and down like a yo yo and the plants haven't coped very well I'm afraid
I grow french marigolds in the greenhouse and don't seem to be troubled by green or whitefly
Don't let this years problems  put you off though, greenhouses are easy when the season plays ball

[sarah-king]

I've same probs with peppers!!! toms on a go slow (no flowers yet) I too have just got greenhouse I'm putting it down to the rubbish weather! I'm hoping all will catch up!!

[Paul Plots]

Some good advice from mumofstig…

The long cold start to the growing year has not helped – this then followed by the sudden “heat wave” and several cold nights also added to the stress new greenhouse plants under went. I think it was the big range of day to night time temperatures that caused the problem for tender establishing plants.

Try a soapy water spray to reduce green and blackfly numbers while you increase the ventilation to make conditions less homely for the bugs. You will also get tougher plants.

Those yellow plastic sticky-strips are useful suspended just above plants infected by aphids. The bugs are attracted to them and then stick so reducing the numbers.

Keep going… things will improve as the weather evens out more.