Parthenocarpy !

[marchogaeth]

I wouldn't discourage you from having a go (as if) but strongly suspect that many more factors will come in to play, like the weather (even for a greenhouse/tunnel) and the variety's natural days to ripeness. You'd be hard pushed to beat a Latah tomato for being ripe early, equally many vaieties will keep going well past when they can really ripen outside - just don't take the top out and grow them "down the other side or along". It will only be a fair trial if you try none P varieties alongside. I did grow Parthenocarpic courgettes in the tunnel for a couple of years but once the ones start in the garden you don't need something that size in the tunnel but the seeds make it too expensive to just pull up and chuck away!

[Thelma Sanders]

I didn't know that! A spray to make tomatoes set fruit parthenocarpicly (??) when the weather isn't good enough for them to self pollinate. From googling it seems they use it quite a lot in the States

Bonide 543 Tomato And Blossom Set Spray-8OZ TOMATO BLOSSOM SET: Amazon.co.uk: Garden & Outdoors


It would have to be a super Summer before we'd suffer temperatures too high for fruit set
I did have trouble this year with little setting on the first trusses because of the nights were still cold, though. The spray is expensive - but the write ups for the parthenocarpic toms aren't good

Partenon courgette does set fruit earlier than the others though, I usually start one early indoors then into greenhouse as soon as poss for the earliest fruit. It soon runs out of oomph without any extra feeding, but by then the outside ones have started fruiting, so I can bin it. Oh and strangely, you do get a few male flowers on P courgettes and P cucumbers, like La Diva - which I grow, as well.

Bear in mind that toms, cukes and 'gettes all still need warmish weather - so IMO you only gain a few weeks even using the greenhouse .

[veggiechicken]

Some P. Cucumbers that have been trialled outdoors. Just adding the link here to remind me.
http://www.seaspringseeds.co.uk/blog...oor-cucumbers/

[Thelma Sanders]

Yes, I've grown La Diva outside - when all those I sowed for the greenhouse managed to grow without committing suicide, so I ended up with too many

They do like a sheltered spot though - they don't like a windy place.