This is very much a personal choice as to manage a lawn in a shady area takes a bit of work and persistence above and beyond seasonal treatments. The alternative may be to re finish the area with a different surface, patio, shingles or flower bed but if its a lawn that you want...
- Shade and food shortage make it difficult for grass and easy for moss
- Keep the area regularly spiked to aid drainage and improve aeration so nutrients can reach the roots
- Regular overseeding the area using a specific seed ideal for shady areas will help thicken the grass in spring and autumn, but don't apply too much as this will have the opposite effect and hold too much moisture again allowing moss to thrive
- Remove low hanging branches from trees to help get more light into the area
- Algae – a green or black slime may appear where water drips from branches, good spiking and top dressing will help improve the situation