1. Sunlight: Plants use sunlight to perform photosynthesis, the process of converting light energy into chemical energy (sugars) for growth.

2. Water: Water is essential for transporting nutrients throughout the plant, maintaining turgor pressure (rigidity), and for various metabolic processes.

3. Carbon Dioxide: Plants absorb carbon dioxide from the air to use in photosynthesis, building sugars for growth.

4. Nutrients: Plants need various nutrients like nitrogen, phosphorus, potassium, and others, which they absorb from the soil through their roots.

5. Oxygen: While plants produce oxygen during photosynthesis, they also need oxygen for respiration, which releases energy from sugars.

6. Space: Plants need adequate space to grow their roots, stems, and leaves. Overcrowding can lead to competition for resources and stunted growth.