Posted: 16/03/2017 at 09:13
If you can, buy a scarifier. They're not that expensive and don't take up much space but they certainly earn their keep.
As for products, read the instructions on the pack for when and how densely to apply it. You need to let the grass heal a couple of days after cutting before applying chemicals whether organic or not. Don't be alarmed when things turn black. It's a natural process of the treatment but don't overdo the dosage thinkin it'll be faster. Yo'll just burn the grass too.
If there are large bare patches after you've scarified, rake the soil loose as it will be compacted and then, in April, sow a suitable seed - for shade, sun, hard wear etc. It will take a few weeks and you'll need to water the seed if it doesn't rain. Lave it to grow a few inches before giving it its first cut on the highest setting. This will encourage it to strengthen and thicken.
Never cut the rest of the lawn shorter than one inch high as this weakens the roots and allows weeds and moss to compete and grow.