If a cannabis plant is Potassium Deficient, it can show signs on the old and new growth right from the start. People often mistake Potassium Deficiency for several other issues because of how similar the results appear. However, it is unique in that the fan leaves will burn at the tips and around the edges, and then turn a light yellow in the middle of each finger of the leaf. These signs are often confused with nutrient burn, but the difference is nutrient burn only happens at the tips of the leaf, while Potassium Deficiency happens around the edges as well. Also, sometimes the leaves will turn white where they are burnt with Potassium Deficiency. Sometimes this looks very similar to Light Burn, but the difference is Light Burn will start to show on the top growth first, where Potassium Deficiency will start everywhere.
How to Cure:
While most cases of Potassium Deficiency are caused by an improper pH level, it is still possible to be due to a lack of nutrients in the growing medium. Especially for those growing in inert mediums, such as coco coir or even hydro. If your pH levels are correct, you will want to look for a supplement high in Potassium so that you can add it to the mix. Remember that the K in N-P-K stands for Potassium, so look on the nutrient labels for a higher ratio. If you are using a nutrient pack or starter kit like the Fox Farms Trio, then you will be covered on the Potassium front! Just be sure to pH properly, and you'll be all set.
Fox Farms Nutrient Trio
GO Flora Trio Series