Confused as to when Tomato plants can go out...

Hello

I'm in London and pretty good chance we won't have a frost again now - the last frost date according to one site was mid-april, but many people seem to say May 15th or around, but that seems to be bandied around for various regions.

Either way, when can you plant tomatoes out? I've read the pollen won't form properly if the temp is below 10 (or maybe 13C) overnight, but if plants are still growing without flowers can they go in the ground now \ early May if the night time temps will be 6-9 C?

My garden gets shaded at this time of year as I have some large decidous trees that are now getting lots fo leaves and blocking light, so the pop up greenhouse is shaded from around 11am to 3pm and won't get any sun before 8.30am or after 6pm.

I have a greenhouse at the allotment I could move some plants to but assuming I should only go once, will have to leave the door open as that gets full sun pretty much all day and gets very hot - which would mean colder at night but less wind I guess.

Sorry this is longwinded, but should I keep my tomato plants (some large ones 50 or so cm tall, and some just a few cm potted on to 7cm pots) at home in the shade, move them and risk some planted outside, or some in the greenhouse?

Thanks

right best get out and start clapping!

Al

Edit - I should add at present I take them outside each day and bring them back in each evening which I can keep doing for a while so they are day hardened off as such but none have stayed out at night.

I see - I suspect it might be June until that happens to I may just experiment then \ risk some as I definitely can't keep them all in the house til June with the size they will get to. will pop soe of the varieties I have a few off \ backups growing in the greenhouse and see how they go - the allotment one might be warmer than mine as it will get sun much later and earlier.

These were early but I guess this means without a heated greenhouse getting started even in March is ambitious if they are destined mostly for outside, or even an unheated greenhouse.

Mine go out onto the allotment May 18th. I 'gamble' by putting a couple out a week earlier, but there isn't much point in this really..

I am also slightly confused, sorry to add. Is my polytunnel equivilant to a normal green house eg I can plant out early may, if I cover with fleece on cold night?

I am also slightly confused, sorry to add. Is my polytunnel equivilant to a normal green house eg I can plant out early may, if I cover with fleece on cold night?

What I have gathered from the posts above and some further research is that basically outdoor, polytunnel or greenhouse, the minimum nighttime temperature should not be below 10C. if it is it can stunt growth completely or slow it down, and when in flower can affect the pollen (I have 2 plants in flower now!). I have read that it can cause 'unexpected tomatoes' ie too small, more prone to splitting etc though I'm unclear if this just affects the trusses that have developed when it is cold, or all (I assume the former).

I believe one advantage of the greenhouse or polytunnel is that plants are less affected by the wind which I believe can also be a large factor \ benefit compared to plants in the ground outside.

With all that said, I've no idea how you plant without a heated greenhouse assuming earliest nighttime temps consistently 10C will be sometime in June.

I'm going to have to try a few sacrifical ones and see what happens - next year I think actually I'll hold back
 - mine were planted late Feb and then again early April but both seem early based on the above - the feb ones I knew were in fairness and I was warned!

My major issue now is that I have to trade off more sun + cold nights vs less sun and warmer nights - I'm not sure what is best out of those, though I guess it seems fairly conclusive that cold nights are not good.

Good luck and I hope that helps!!

Al

It's also down to shelter from the wind, shade, position of GH, and other conditions like proximity to warming brick walls etc.

This year, I planted out nineteen pots of soil/compost in the GH on 15th April, which is the norm here.

The other forty-five are raring to go while being hardened off as seedlings about four inches high, and shut up at night...

We have an enormous yew tree behind 'The Turrets', which puts everything in shade from lunchtime onwards, but at this time of year, all the other factors as above kick in, and everything gets about seven hours morning sunlight which is what toms seem to like more than heat!