Potassium as a foliar spray for tomatoes?

[imthedude]

Hi all.

A couple of my tomato plants have some very blotchy tomatoes on them, leading to think they might be looking for some more potassium. Have any of you tried a foliar application of some form of potassium, and if so, did it work?

TIA

[frankva]

I just whacked mine with Muriate of Potash. Heaping T in a 5 gallon bucket. Takes a bit to dissolve. 3 qts per plant. (Blue Maxwell House plastic jug.)

Have not tried foliar.

Seems to help them fight off the various poxes I get here due to humidity and fog.

Repeat. I have not tried foliar.

[Paquebot]

Tomato plants have no means of absorbing potassium through their leaves. (Potassium is not available to plants in a gaseous form so they never developed the ability to obtain it that way.) It only helps the plants when whatever is sprayed on them reaches the soil and eventually down to the roots. If plant is deficient in potassium, best use is applied directly to the soil.

Martin

[MichaelK!]

Originally Posted by Paquebot

Tomato plants have no means of absorbing potassium through their leaves. (Potassium is not available to plants in a gaseous form so they never developed the ability to obtain it that way.) It only helps the plants when whatever is sprayed on them reaches the soil and eventually down to the roots. If plant is deficient in potassium, best use is applied directly to the soil.

Martin

I'm not sure about that. I have prepared soluble iron spray and I've seen dramatic results in 3-4 days. Adding a bit of detergent to the spray helps the liquid penetrate inside.

I would think thought that potassium translocates quickly through the plant and just watering the soil with some soluble potassium fertilzer would work quickly.

[Paquebot]

Stop to think of something you may have learned in 6th grade science class. Trees are the most common form of vegetation which is able to regulate the directional flow of liquids within the plant. Most annual plants do not have that capability. When a tomato plant suffers from lack of water, it wilts from the top leaves downward as water is lost through them first. Spraying water on those leaves will not revive the plant since it has no provision to take in the liquid and reverse the flow. The water flow is only from the bottom upwards. That's also why spraying calcium on a plant to prevent blossom end rot is impossible.

Martin