DIAGNOSIS This is normal for the standard White and Color Ambiance bulbs; they use a limited color gamut (mainly red, lime, blue) and cannot produce saturated deep greens or cyans.
FIX You cannot 'fix' this on the standard bulbs. To get richer greens and blues, you need the higher-end Hue White and Color Ambiance with richer colors model (product code starting with LCT0xx), which adds a dedicated green LED.
- Check your bulb model in the Hue app under Settings > Lights > [Bulb Name]. If it's LCT001/003/etc., you have the standard gamut.
IF THAT DIDN'T WORK Ensure you're not using a "Scene" that mixes white with color. Try the pure color swatches (like "Saturated" or "Color loop") for the most intensity.
HEADS UP The perceived color is also heavily influenced by your lamp shade. A white shade will dilute color saturation significantly.