Posted on by Jason G

My stems are purple!

This is a quick tutorial on what to do (or not to do) if you experience purpling of the stems when transitioning from growth to flower.

A lot of new and experienced growers alike have made a shift to full spectrum LED because of the amazing growth, quality and now finally, amazing yields.

The trade from HPS > LED is most certainly a more cost effective way of producing similar or more in flower weight, for some though an unexpected nutritional response has changed a few things in relation to feeding.

For those with LED lighting systems containing UV light, the purpling of the stems and petioles is completely normal, and is solely an expression of pigmentation, usually displayed by plants that will express purples and reds in late flower during maturity.

If you are using an LED that does not contain any UV LEDs in, then you more than likely have a deficiency.

The deficiencies displayed:

  • Petioles completely change from green to purple > Insufficient amounts of Magnesium (Mg)
  • Main stem has slight pink/purple striping > Insufficient amounts of Potassium (K)

In a majority of cases these deficiencies can be simply corrected by slightly raising the dose of main food/nutrition, particularly increasing your overall A/B base nutrient feed will usually solve this issue. Remember to gradually increase the nutrient strength to avoid and 'burning'.

However in some cases, you may need to amend an additional element in line with the plants needs, one thing to remember though is the synergism and antagonism of nutrients, by adding elements in greater amounts contained in the base food, the concentration can shift making other elements unavailable to the plant.

Never just add something because the bottle says it will fix, ask you local representative as to the potential problems you need to look out for.