[AndyRVTR]

I sowed my maincrop potatoes in one of the raised beds on 30th March, varieties were Mozart, Maris Piper and King Edward. All the seeds were chitted and planted using exactly the same method, however, the Maris Piper & Mozart have totally failed to grow, I mean not even broken the surface! The King Edward were my own saved seeds from last year and they are absolutely thriving, unfortunately, after digging a few of the others out, the chits are the same size as when they were planted. The MP & M were bought from the supermarket, but saying that, I bought MP from the same supermarket last year and they grew ok?

[Aidy]

So the question I was once asked by a farmer who is one of our patients.... why are you planting main's so early when you are going to store them?
I was like you sowing in March.
I now follow our local farmers. Mains go in first weekend of May, my earlys 2nd weekend of April.
Done this about 4 years now and always get very good crops, others on site are moaning coz they have lost a good few due to more than average raInfall. They will not learn!

[AndyRVTR]

That's a great point re storage Aidy, this year however, mrs R and myself arent storing any as we're not eating potatoes (keto lifestyle).
I'm just growing them for family to use as and when they're ready, I just don't understand why half grew and half didn't, could they have been treated with something to prevent them growing as normal?

[hasbeans]

A fair amount of fruit & veg gets growth suppressant but I didn't expect spuds did given the state a lot are when I get round to eating them.  Get to the supermarket and buy some organic ones.

[Yorkie]

Unless they are certified seed potatoes, you really shouldn't buy potatoes from the supermarket for planting. You have no way of knowing what viruses they may be carrying.

[AnneB]

So the question I was once asked by a farmer who is one of our patients.... why are you planting main's so early when you are going to store them?
I was like you sowing in March.
I now follow our local farmers. Mains go in first weekend of May, my earlys 2nd weekend of April.
Done this about 4 years now and always get very good crops, others on site are moaning coz they have lost a good few due to more than average raInfall. They will not learn!

That's interesting Aidy.  I have always followed the advice given by the late Joe Maiden, who used to have a radio show on Radio Leeds, and whose book Grow with Joe is an excellent one.   He recommended planting all types of potatoes at the same time, 1st earlies, 2nd earlies, early maincrop, maincrop and salad.  His rationale was that early potatoes take approximately 12 weeks, second earlies 16 weeks, early maincrop take until August and maincrop until September. 
I follow this method, usually planting mid April here in Yorkshire and it works well for me.

[AnneB]

That's a great point re storage Aidy, this year however, mrs R and myself arent storing any as we're not eating potatoes (keto lifestyle).
I'm just growing them for family to use as and when they're ready, I just don't understand why half grew and half didn't, could they have been treated with something to prevent them growing as normal?

I agree with hasbeans that your supermarket potatoes have probably been treated with a growth inhibitor. I also agree with Yorkie that it's best to get certified seed potatoes, especially if you are growing on an allotment where disease can spread to other plots.

[Aidy]

So the question I was once asked by a farmer who is one of our patients.... why are you planting main's so early when you are going to store them?
I was like you sowing in March.
I now follow our local farmers. Mains go in first weekend of May, my earlys 2nd weekend of April.
Done this about 4 years now and always get very good crops, others on site are moaning coz they have lost a good few due to more than average raInfall. They will not learn!

That's interesting Aidy.  I have always followed the advice given by the late Joe Maiden, who used to have a radio show on Radio Leeds, and whose book Grow with Joe is an excellent one.   He recommended planting all types of potatoes at the same time, 1st earlies, 2nd earlies, early maincrop, maincrop and salad.  His rationale was that early potatoes take approximately 12 weeks, second earlies 16 weeks, early maincrop take until August and maincrop until September. 
I follow this method, usually planting mid April here in Yorkshire and it works well for me.

We have a chap from Ireland on site, his way is...  "in with Paddy, out with Billy"
So 17th March he was on sowing them, not long after he was F ing and Jeffing coz they were sat in water for days, he has lost at least half his crop!
Our last frost date is around end of April now so this why I always hang on.
You find the best way that works for you in your area.
Good luck hope you get a good crop.