When plants cannot get the nutrients they need, they do not function properly, adversely affecting growth and yield. This can occur in any growing medium, while using any planting mix or technique—coir, rockwool, soil, soilless, hydroponic or aeroponic. Plant disorders are characterized by their symptoms, which appear more quickly in hydroponic gardens than in planting mixes or soil.
An overabundance of nutrients can result in nutrient burn or toxicity and can also lock out other ingredients. Unless the damage is slight, individual leaves do not recover from nutrient deficiencies. Some nutrients are mobile and are translocated from older to new growth, so the damage is seen in older leaves, not in new growth. Other nutrients are not mobile. Their deficiencies are apparent in new growth.
All fertilizer packages list three numbers that identify the N-P-K ratio. They usually appear as three numbers with dashes between them such as 25-10-10. The first number represents nitrogen (N), which is responsible for foliage or leaf development. Fertilizers that promote heavy leaf growth have a higher first number (N) than the other two. The second number represents phosphorus (P), which is important for strong stems and flowering. The third number is potassium (K), which promotes healthy metabolic function. Sometimes micronutrients are listed after the macronutrients: These are calcium (Ca), copper (Cu), manganese (Mn) and zinc (Zn).
All nutrients are required to be present for proper metabolic function. Most growers use premixed nutrient systems and faithfully follow the manufacturer’s feed schedules, and they never see deficiencies before they flush their plants. Two deficiencies that may appear when using commercial fertilizers are calcium and magnesium. On the other hand, organic living soil and outdoor plants that do not receive supplemental nutrition are more often subject to deficiencies, but only because living soil systems have more variables involved in delivering nutrients compared with concentrated nutrient products.
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