The four ingredients needed by a plant to perform photosynthesis are:

1. Carbon Dioxide (CO2): This is absorbed from the air through the plant's leaves.

2. Water (H2O): This is absorbed from the soil through the plant's roots.

3. Sunlight: This provides the energy needed to power the chemical reactions of photosynthesis.

4. Chlorophyll: This is a green pigment found in plant cells that absorbs sunlight.