[Kagganz]

.... in the same soil?

Owt or Nowt   :blink:

Just plotting and a plannin' ya see      xxx

Ooops  should have mentioned they will be early potatoes !

[RichardA]

usual to get some plants ready elsewhere in seed rows or in greenhouse or cold frame and then with any due adjustment to ph or needed fertilizer can follow with leeks, cabbbages, salad stuff, or if early enough with beans or peas or sweet corn plants, courgettes, marrows, etc. Once potatoes are up can put in whatever the season is right for at that time.
No need for land to stand idle.
R

[skewball]

I tried Sweetcorn following first earlies last year having got them going in paper pots. Never quite made it. Season ended before they fully ripened.
Also tried leeks that had been grown in the Cat Littler tray but again, were not that great. Both just seemed to lose too much time getting ‘settled’ after being transplanted. To work I think you have to get the earlies up straight away and store and get Leeks/Sweetcorn in literally the same day.

Might try courgette this year and then some things like Pak Choi, spinach etc.

[mumofstig]

In order for summer crops to work after potatoes, the earlies do need to go in (and got out) as early as possible in the season.

Leeks are a pretty traditional follow-on crop for earlies, but all the things on Richards list would work.
Speedy green beans I can recommend as they really do crop in about 8 weeks , so I pop some in anywhere there is a gap

[Kleftiwallah]

Look up "Crop rotation"  or the three/four crop rotation.   It's all there!    Cheers,   Tony.

[DD.]

I think the OP means as a follow on crop, same year, not next time around.

[solway cropper]

I'll be putting maincrop leeks in after my early spuds. If you get the leeks sown early you can get them to a good size by the time they're ready to go in the ground.

I grow quite a few first earlies in large containers and these are normally followed by french beans or salad crops.

[Swing Swang]

I do exactly as solwaycropper too.
Could also sow squash.
Other option would be a green manure - consider field beans if they fit in with your rotation - they are edible and even if the beans don't reach maturity there's always the tops or the pods.

[Kagganz]

   Thank you everyone

xxx

[JaK]

Last year I followed them with dwarf beans and they did really well. Doing that again this year and also trying pattypan squash  as a follow on crop too.

[prakash_mib]

same result
dwarf french after earlies (sowed around mid may in paper pots) and planted them.
had a very good produce. 

[Yorkie]

Just to point out that spuds are quite a hungry crop, so make sure if planting things like squash or beans, that you add extra fertiliser to the soil too.