What causes lots of small poatoes?

[kyj]

Can anyone give me any ideas as to why some of my potato plants have produced lots of small potatoes and no larger ones? Variety? Weather? Soil? Any thoughts? Thanks in advance!

[The Riff-Raff Element]

Insufficient water perhaps? Was it dry?

[bill1953]

Did you earth them up as they grew taller all the time?

[seasidegirl]

I think lack of water is most likely but also maybe planting them too close?

[bill1953]

Most likely cause can also be lack of nutrients.

[demi]

yes lack of water is the most common cause of wee spuds.

[The Riff-Raff Element]

Most likely cause can also be lack of nutrients.

You know, it occurred to me, while I was examining the spud bed for signs of life this evening, that what could also be causing problems is an imbalance of nutrients.

Potatoes (actually roots in general, but particularly spuds) need relatively little nitrogen compared to their requirements for potassium and phosphorus. The logic is the nitrogen tends to promote stem growth and root growth and the roots produce a profusion of spudlets rather than decent sized bakers due to a relative lack of the other minerals.

You might try supplementing your potato patch with phosphate rock or bone meal for the phosphorus (bone meal is a good bet if your soil is not rich in lime as it also provides the calcium potatoes need too) and mined potash, wood ash (watch the pH of your soil) or potassium sulphate for the potassium.

[kyj]

Thanks everyone. We are always dry in the summer, but having dug a new spring just for the garden this year it's not so bad as it has been so I'm leaning away from that one. Lack of nutrients is also a perenniel problem (peaty soil), we heaped on the manure last winter which I would have hoped would help - cerainly the soil texure was much improved but perhaps the balance of nutrients is not right (?).

One of the other potato patches had better results - but then I planted a different variety (desiree), also the soil is deeper there.

We don't have access to posphate rock, potash or bone meal (unless we can make it ourselves?), but could certainly generate wood ash. We do have ready supplies of seaweed and horse, chicken and sheep manure.

[The Riff-Raff Element]

Of the three manures, chicken has the lowest relative nitrogen content compared to its phosphorus & potassium levels, so I'd suggest favouring your potatoes with a compost made with this and some wood ash. Seaweed is, of course, brilliant as a source of micro nutrients, but barely registers on the NPK scale, so you can use that everywhere.

[oldjerry]

Sorry to state the bleedin'obvious,but have we sorted out which variety you're having probs with? If you've planted a salad variety,you can expect lots of small spuds!

[kyj]

Well it's a good thought. But these were King Edwards. At least they were supposed to be.

On the other hand we had reserved seed potato from the previous year's crop, so there's always room for error (but we''ve not grown and salad varieties yet).

Thanks for all the thoughts & advice.