To determine how much of the garden still needs to be watered, we need additional information. Specifically, we would need to know:
- The size of the garden area that has already been watered.
- Any specific areas within the 24 m² that require watering (if applicable).
Once we have that information, we can subtract the area that has already been watered from the total area of the garden (24 m²) to find out how much still needs watering. Please provide the necessary details for accurate calculation.