What is the target media pH range for tomatoes in greenhouse production?

• A. 4.5-5.5
• B. 6.8-7.2
• C. 5.5-6.5
• D. 7.0-7.5

Answer: (C)

The nutrient availability in the root zone is what this question is testing. Tomato plants in greenhouse systems rely on a slightly acidic environment so nutrients stay soluble and can be taken up efficiently. The optimal media pH for tomatoes is about 5.5 to 6.5. Within this range, essential nutrients remain available in the right amounts: micronutrients like iron, manganese, and zinc are accessible when needed, while the major nutrients can still be absorbed effectively. If the pH drops too low (below 5.5), some nutrients become overly available and others can be less balanced, and there’s a higher risk of toxicity from elements like aluminum and manganese. If the pH rises too high (above 6.5), iron and other micronutrients become less soluble, leading to deficiencies and symptoms like chlorosis. So the 5.5 to 6.5 window keeps nutrient availability balanced for healthy tomato growth.