[Twood]

HI
I'm thinking this subject could be quite divisive but hopefully useful
I dont have enough room to plant spuds in the ground so am opting for bags this year to see how I get along Its my first year growing veg in this new garden.
So I ordered from Marshalls and have received 3 good quality but small 40L bags and 3 varieties of seed potatoes ( x5)  Swift, Charlotte and Wilja which all seem to be decent varieties.
However having done a bit of research my issue is the diverse information regarding the number of seed potatoes per bag.
Marshalls suggest all 5 seed potatoes per bag.
John suggests 3 and I have read other information suggesting 2.
So I'm sure there are lots of you out there who have both good and bad experiences with this method
All comments gratefully received 
Anyone tried main crop in bags??

Twood

[DHM]

When all we had was a patio, we grew potatoes in bags for 5 years, some years, loads of 'em, some years nowt. I did 3 mains or 4 salads to a bag and most of the time had decent crops. The method of topping up is very easy in bags and is a simple low-labour way to grow them.

The only problem I had was disposing of all the soil afterwards as you can't reuse it for potatoes or tomatoes the following year due to the nutritional take and disease build up. Luckily a local charity took it off my hands to fill their herb planters!

[Plot94]

My best results have come from 1 potato per 30 litre pot grown in a mixture of MPC & horse manure. Whenever I have tried more than 1 in a bag or pot the yeild has been very disappointing, this could be down to not enough food per plant or not enough water but 1 works best for me. Might be a bit of trial and error to see what works for you.

[mumofstig]

As none of your potatoes are maincrop varieties I'd go for 3 per bag,  but don't forget to add a good handful of Fish, Blood & Bone, or other fertiliser to the compost - it makes a huge difference to final yield
JBA potato growing in bags advice here
https://www.youtube.com/watch?v=PoIlfe6bGwk&feature=channel_page

[Yorkie]

I agree that 5 might be a bit too many.

In addition to feeding them as MoS suggests, watering a lot is key once the tubers start to swell as Plot94 mentions.  If you don't water properly then the yield will always be small.

[Tenhens]

We did about 30 bags last year with 2 seed pots per bag , with a mix of soil and home made compost and some potato fertilizer from our plot shop . The challenge is getting the watering right , we thought we were doing ok until we harvested ,the yield was low and the compost was rather dry .  Last summer was dry to the extent that we emptied our IBC cube - 250 gallons - the first time in several years.
We hope for a better 2019!!

[sunshineband]

In order to et the water down further than the top couple of inches, I insert a large plastic pop bottle, mouth down with the bottom cut off, and holes poked in the sides, when there is about another 30 cm or so of earthing up to do. It does seem to help and allows water to get into the soil more evenly

I know this is not the answer to the original question, but it seemed worth mentioning.

[Mac Campbell]

Hi -
I carried out some experimentation last year with potatoes in bags. After chitting I reduced down to two shoots and in one bag I used one potato, and in the other I used two potatoes.
The two potato bag I earthed up as normal and watered accordingly.
The one potato bag I earthed till approx half way up the bag and then instead of earthing up I used straw. This kept the soil/compost much damper and led to less watering.
Final result was not really much different though the produce from the single potato were more uniform and larger but some potatoes had green on them.
The produce from the two potato bag were noticeably smaller but no green at all.
On hind sight I think I could have harvested the single bag earlier. But hey ho they all got eaten.

[mrs bouquet]

I have only ever grown spuds in bags and have always been pleased with the results.   Like Sunshine, I put some plastic rigid tubing down the bag sides to distribute the water to the roots, and earthing them up is easy as well.  Good luck,  Mrs Bouquet

[Twood]

Well lots of useful information
thanks everyone who responded. I will be using some of these tips and I'll see how I get on. Lots of watering seems to be the essential tip here.
I like the bottle idea. I read about that somewhere else... could have been on here but putting the bottles down between tomato plants so that they are watered at the root.
Good luck everyone

[Tenhens]

In order to et the water down further than the top couple of inches, I insert a large plastic pop bottle, mouth down with the bottom cut off, and holes poked in the sides, when there is about another 30 cm or so of earthing up to do. It does seem to help and allows water to get into the soil more evenly

I know this is not the answer to the original question, but it seemed worth mentioning.

What size bottle did you use? 
Have thought about using milk bottles but they don't seem that robust. The 1 litre squash ( Vimto ) seem better suited.  I'm guessing that by getting the water further down there is the potential of less evaporation.
Interesting comment from Mac Campbell about using straw.

[DHM]

What does everyone do with the compost once the spuds have been harvested?

[mumofstig]

Either add some fertiliser and use it to grow something (from a different veg family) next year - or just tip it onto soil to improve it, or flower beds as a mulch.

[Grubbypaws]

Feed the compost and plant out your purple sprouting broccoli which have been growing in pots or fill smaller containers with the compost and grow courgettes. If you have done the former you can use the compost to grow courgettes the following year. After the courgettes are done use it as a garden mulch 

[rowlandwells]

 my wife plants our early crop  potatoes in potato tubs  year on year the  potatoes in tubs  last year where charlotte swift and red Duke of York and because they where near the house we where able to keep them watered as we have no water down the allotments we also added a bit of potato fert and they turned out ok


the one thing I hate with new potatoes is if they get to large just under the size of a golf ball is fine for me but as said no problem growing in tubs but I assume the same result would be if your growing in potato bags


the only downside as i see it is the cost factor of using good compost in the tubs we used grow bag compost slightly cheeper and we used the spent compost down the allotments on our raised beds so really ther was no waste