Lavender

@Gardenergrower Hmmmmm its hard to say but one thing is for sure your plant is finding it very hard to assimilate the nutrients from within your medium. How is the ph?? Thats where you should look first it should be around the 6.2-6.6 range in soil with 6.4 being a "sweet spot" then if that seems ok you need to ask yourself have I been providing adequate amounts of NPK plus cal and mag? if the answer is yes then move to the roots . Gently dig down and inspect any visible roots they should look fairly white in colour anything brownish and soft will confirm root rot. I personally always use some form of Mycorrhizae in all of my grows be it soil , soiless and Hydro the beneficial bacteria will attack and consume the bad pathogens that cause the rot in the first place. Also remember to let your soil dry a little between waterings as Oxygen is essential to root health. Hope I was able to help mate