My citrus collection [EU - Antwerp]

[Zitrusgaertner]

It may be a phosphorus deficiency.  Tomatoes look like that when there is insufficient phosphorus.  In any case use a water soluble fertilizer and spray with trace minerals for citrus.

  NO! Healthy lemons, ichang papeda and their hybrids show this phenomenon. Nothing to do with phosphorus defeciency which can rarely be seen with citrus. Citrus do not like phosphorus so there nearly always is more than citrus plants need.

[hardyvermont]

Does someone know what causes the leaf stem/veins to turn red like this?

It happens on some of my rooted poncirus cuttings:

What is the current situation?  Were you growing these plants under lights set for a long day and then changed to fewer hours/natural light?  This occurred on some of my 3/4 poncirus hybrids. Change in day length appeared to turn plants dormant.  Poncirus leaves frequently turn color before they fall.

[Peep]

What is the current situation?  Were you growing these plants under lights set for a long day and then changed to fewer hours/natural light?  This occurred on some of my 3/4 poncirus hybrids. Change in day length appeared to turn plants dormant.  Poncirus leaves frequently turn color before they fall.

Yeah the coloring is an autumn sign, it could have been from the light schedule, but at this stage with the leaves grown (during/after rooting) they would have been outside I think. But likely I kept them shaded more than usual because they were young cuttings.