MY back garden doesn't get as much sun as I'd like, and in spite of careful maintenance the lawn grass grows poorly some years and becomes thin. It's typical of many small plots surrounded by high fences or hedges which cast shade. If you have this problem you can rectify it by spreading fresh grass seed over the lawn area to thicken up the sward' in the spring - that's now!
Buy good quality, new grass seed suitable for tough lawn use (it should say this on the box). Fine grass seed for fine lawns doesn't grow as vigorously. You'll also need soil based compost -1 use John Innes No3 - to cover them after spreading the seeds. If you don't do this the birds will eat the seeds!
To start, on a warming, dry day mow the lawn on a medium height setting and clear any debris from the surface. The lawn surface then needs raking out to remove moss and rubbish, and fluff up the soil a bit to accept the seed. I started with a spring tined rake, which works fine but is hard work. My electric scarifier made the job a lot easier. Clear off and compost all of the raked out material. If the soil is dry on the surface, water it thoroughly with a hose before seeding.
Here's how I went about it:
Fix bare patches
YOU don't have to do the whole lawn. If you just have a bare patch where grass has died off, clear off debris then rake the surface to loosen the soil.
Water it if dry. Spread fresh grass seeds evenly and thinly over the bare area, overlapping the grass around the edges. Top dress lightly with sieved compost, water with a fine rose to settle. Cover with netting until seeds germinate.
How to overseed a lawn
Mow the lawn on medium height setting. Rake out moss using a spring tined rake. An electric scarifier (inset) makes the job easier.
Lightly overseed the whole lawn area with fresh, hard wearing grass seed mix, spreading the seeds evenly across the whole area.
Cover the seeds with a fine layer of compost such as John Innes No3. Spread it through a medium sieve to remove lumps and distribute it evenly.