Gherkins, care and harvesting

Just been given some gherkin plants, how do I care for them and what care do they need in a greenhouse or outside and when should I harvest them please?

 

In essence they are just small cucumbers. You'll probably get away with growing outside, but if you have a greenhouse they'd probably do better.
You don't need to support them like normal cucumbers - just let them trail along the ground. If you nip the tips above the 5th leaf they'll spread out.
Harvest when a couple of inches or so long. You can leave them to grow bigger if you like your gherkins big though. Feed them once the first fruit has formed.

 

How big will the plants grow? I have eight plants growing together in seperate pots. Should I space them around the green house?

 

Much depends on the size of your GH. In our 15 foot polytunnel I'm growing three on one side of the path between tomato plants. Last year mine ended up about 5 feet long with side shoots.
Eight plants seems a heck of a lot unless you plan to sell cucs or have plenty friends you can give them to.