Flopping over is a symptom. Staking it is treating the symptom, not the cause.

Many things could be wrong,

• Is it over watered or under watered? Both are bad. Many inexperienced gardeners think that more water cures all ills
• Insects! Look for big ones. Look for itty-bitty ones
• Diseases. Are the leaves yellow, or brown, or spotted?
• Weather. Is it too hot or too cold?
• Are other nearby plants wilting, or just this one?

My first guess would be lack of water. Most plants that wilt from lack of water respond quickly if watered in time.