Growing watermelons in the uk? Other ideas?

Hello All,
We have a wonderful large greenhouse on our very sunny allotment plot. I’d love to grow watermelons but read the seeds need 21C for at least 10-14 days to propagate and even in summer it’s not that hot in there in the evenings. Plus I can’t go there every day to water them for at least another month.
Please can anyone recommend any good seed varieties? Would like large ones if possible!!
Plus. Any ideas what else we could grow? I’ve only got a few tomato plants in there so far! Looking for interesting unusual edible things. Not pineapples as that seemed like it takes years to get even one more pineapple!! Thank you!

 

Also the lady we got the greenhouse from said her tomatoes failed last summer as it was too hot in there!! Where we’ve put it it literally gets full sun the full day. So likely hotter than where she had it between 2 buildings. It’s only been up a few weeks and not been able to go there much yet.
How about any cacti?!

 

Must admit, I've never tried water mellons. I did a quck internet search simply searched. Growing water melons in UK. Plenty of info plus some vidio clips.

 

Hi Mike
Thanks for reply, yes I searched too and posted just to see what people on here have experience with

 

Not fond of water melons myself. However your greenhouse looks to have got one louvre and two opening roof vents; not really enough for this size greenhouse. I would look to put in another two roof vents and another couple of louvre vents low down on opposite sides of the greenhouse. I would also strongly recommend fitting automatic openers to the roof vents.

 

Hi @LoveSunshine it's a bit late in the year to start things like melons now I would have thought. I would suggest that next year you start off the seed in your house on a window sill, and only move it to the greenhouse in May. But why not use it to grow things like mangetout early in the year, or tubs of new potatoes for Christmas dinner? Or grow fancy mixed leaves for salads. I also grow pots of different basils - cinnamon, thai and italian. They don't like being outside.
If you can't water every day, have you considered a big water butt and an automated system (would need batteries for pump and timer)? NigelJ is right about adding more vents - I have 3 sets of double roof vents and 4 low sets of louvres, I leave the door open all day and have lots of shading net, yet still have trouble keeping the temperature down.

 

Don't have experience with a greenhouse but I have the use of a polytunnel on my allotment site, 2 years ago I had some really good beginners luck. The seed was "sugar baby" from lidl. Also managed to germinate some from a honey dew melon from asda..ended up, one had mildew, the other 2 just died.

But from the sugar baby I had 2 quite healthy plants.
Lots of watering, chicken poo pellets mixed with mpc and a dash of bone meal and then regular feeding with tomato feed..









Probably could have done with a bit longer to ripen fully but I was too excited!

Last year was a poor show just 1 melon and it was very bland. No pics ..it was that bad lol

This year I have 3 plants (desperately need potting on), 1 is sugar baby (R) and think the other 2 are "alavaro" (L) . I did have 2 "outdoor wonders" growing but... I wonder why they died