Not all plant problems are caused by insects or diseases. Sometimes, an unhealthy plant is suffering from a nutrient deficiency or overload, meaning too much of any one nutrient. Plant nutrient deficiencies often manifest as discoloration or distortion of the leaves and stems.1 Unfortunately, many problems have similar symptoms and sometimes it is a combination of problems, so managing the problem can be a bit of trial and error.
Before you try to fix your plant with too many supplements and kill it with kindness, be sure you eliminate other obvious causes for sickly plants:
Check first for signs of insects or disease.
Foliage discoloration and stunted plants can easily be caused by soil that is too wet and drains poorly or soil that is too compacted for good root growth.
Extreme cold or heat will slow plant growth and affect flowering and fruit set.
Too much fertilizer can result in salt injury. Your plants may look scorched or they may wilt, even when the soil is wet.
If you can't seem to remedy the situation, bring a sample of the ailing plant into your local cooperative extension service for a definitive diagnosis.
What Nutrients Do Plants Need?
Plants require a mix of nutrients to remain healthy. Nutrients that are needed in relatively large amounts are called the macronutrients. Plant macronutrients include nitrogen, potassium, phosphorus, calcium, sulfur, and magnesium.
There are a handful of additional nutrients that are required for plant growth, but in much smaller quantities. These micronutrients include boron, copper, iron, manganese, molybdenum, and zinc.
How Do Plants Receive Nutrients?
All of these nutrients are taken in through the roots. Water transfers the nutrients from the soil to the plant roots, so water is one key requirement of sufficient plant nutrition.
A second requirement is the appropriate soil pH for the plant being grown. Each plant prefers a specific pH range to be able to access the nutrients in the soil. Some plants are fussier than others, but if the soil pH is too acidic or alkaline, the plant will not be able to take in nutrients no matter how rich your soil may be.
check plant symptom guide for more information