phosphorous deficiency and cold temperatures??

RomanX · May 7, 2017

several questions:

how should I (or if) to combat / treat purple-ish stems and leaf undersides of cold treatment seedlings? I know this purpling is a characteristic sign of phosphorous deficiency and that P uptake is impaired by cold temperatures: so what can I do to remedy this? (PS more fertilizer only corrected this for 1-2 days. . . . )

When these seedlings were transplanted outside last week, they recovered almost immediately (for 2-3 days, the weather was unseasonally very warm - in the low 80's) but then came the usual chilly weather (69-70) with daily showers and thunderstorms. The tomato starts are exhibiting P deficiency again: purplish stems, droopy leaves with tips curving down. What should I do?

**carolyn137** · May 7, 2017

Quote:

Originally Posted by RomanX

several questions:

how should I (or if) to combat / treat purple-ish stems and leaf undersides of cold treatment seedlings? I know this purpling is a characteristic sign of phosphorous deficiency and that P uptake is impaired by cold temperatures: so what can I do to remedy this? (PS more fertilizer only corrected this for 1-2 days. . . . )

When these seedlings were transplanted outside last week, they recovered almost immediately (for 2-3 days, the weather was unseasonally very warm - in the low 80's) but then came the usual chilly weather (69-70) with daily showers and thunderstorms. The tomato starts are exhibiting P deficiency again: purplish stems, droopy leaves with tips curving down. What should I do?

If it were me I'd do nothing at all.

They'll snap out of it when they want to or feel like doing so when the weather warms up. Seriously.

Carolyn

brownrexx · May 8, 2017

The plants are not able to use the phosphorus that is already present in the soil when the temperature is too cool. If you keep adding extra phosphorus and then the weather warms up, you will end up having too much phosphorus in the soil.

Too much of any fertilizer can become detrimental to the plant, even toxic.

Wait until it warms up. Your plants will be fine. They are not doing much growing in cool weather anyway.

Cole_Robbie · May 8, 2017

Yep. You are much more likely to harm them by increasing the fertilizer.

May 7, 2017	#1
RomanX Tomatovillian™ Join Date: Jan 2015 Location: North Carolina Posts: 119	phosphorous deficiency and cold temperatures?? several questions: how should I (or if) to combat / treat purple-ish stems and leaf undersides of cold treatment seedlings? I know this purpling is a characteristic sign of phosphorous deficiency and that P uptake is impaired by cold temperatures: so what can I do to remedy this? (PS more fertilizer only corrected this for 1-2 days. . . . ) When these seedlings were transplanted outside last week, they recovered almost immediately (for 2-3 days, the weather was unseasonally very warm - in the low 80's) but then came the usual chilly weather (69-70) with daily showers and thunderstorms. The tomato starts are exhibiting P deficiency again: purplish stems, droopy leaves with tips curving down. What should I do?

May 8, 2017	#3
brownrexx Tomatovillian™ Join Date: Feb 2016 Location: Southeastern PA Posts: 1,420	The plants are not able to use the phosphorus that is already present in the soil when the temperature is too cool. If you keep adding extra phosphorus and then the weather warms up, you will end up having too much phosphorus in the soil. Too much of any fertilizer can become detrimental to the plant, even toxic. Wait until it warms up. Your plants will be fine. They are not doing much growing in cool weather anyway. Last edited by brownrexx; May 8, 2017 at 09:48 AM.

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May 8, 2017	#4
Cole_Robbie Tomatovillian™ Join Date: Jun 2012 Location: Illinois, zone 6 Posts: 8,407	Yep. You are much more likely to harm them by increasing the fertilizer.