Young shoots become stunted, stalks are weak, stems are shorter, and blooms become distorted. It is claimed that a deficiency of potassium will increase a plant's susceptibility to diseases, and produce blind shoots. In our area, it is unlikely that you would see a deficiency of potassium. Heavy clay particles can also interfere with the uptake of potassium since they can displace other mineral ions such as calcium. When potassium is attached to the clay micelle, it becomes unavailable to the plant.
Excessive potassium causes chlorosis, poor root growth, and wilted new shoots.
Since potassium leaches quickly like nitrogen, excesses are rarely seen. Some mushroom composts and manures are very high in potassium and may cause a problem. I would not consider buying large amounts of potassium nitrate since it is one of the main ingredients for the production of gunpowder and bombs. Teamed with phosphorous, potassium is necessary to promote large blooms with good color. This article is an ARS Award of Merit winner.