Adding Phosphorus and Potassium to potatoes in pots

[CoreyPortelli22]

Hi all I am growing potatoes in pots and have been adding a hand full of blood and bone to the soil in the bottom part of the pots, so the roots from the seed potatoes can directly feed from this.
The blood and bone has a low Phosphorus and Potassium level so I am thinking of adding phosphorus and Potassium fertiliser with the blood and blood to bring up the P K levels.
My Question is will adding Phosphorus and Potassium to the root zone of the potatoes burn the roots, Or am I better off adding the P&K on the top off the soil.

 

[Chuck]

I have never known that to be the case. In fact I often use rock phosphate directly on the roots of my tomatoes. But beware of too much phosphorus as this will stop the uptake of other nutrients. AFAIK only nitrogen will burn roots but too much P and K will show as poor growth and production. This is why I am reluctant to advise adding extra phosphorus or potassium as too much of it mimics what a lack of NPK fertilizer looks like.

 

[Meadowlark]

Have you tested the soil? Really only reliable way to know what you need.

Ph is important in growing potatoes...needs to be 5.4 to 5.9 for best growth.

 

[CoreyPortelli22]

Have you tested the soil? Really only reliable way to know what you need.

Ph is important in growing potatoes...needs to be 5.4 to 5.9 for best growth.

There growing in shop bought pine bark compost in pots.