IF you've been frantically raking, weeding and feeding your lawn this spring but it still has more lumps, bumps and bald patches in it than the velvet green carpet of grass you long for, it's time to give it a health check.

A healthy lawn helps encourage wildlife into the garden and grass is highly efficient at converting carbon dioxide to oxygen, something we're all becoming more aware of as CO2 emissions are the topics of the moment.

You may feel your lawn is beyond repair if it's weed and moss-ridden or full of bald patches. If two-thirds of the area is moss and weeds you may be better off starting again, turfing or seeding a new lawn.

But if you do decide that it's worth saving, first cut it keeping the blades set quite high. If your grass is already long, give it a few cuts over a number of weeks, lowering the blades a little at a time, so that you cut the grass length down gradually.

Feed the grass with lawn fertiliser available at most garden centres. This can be done by hand, applying approximately two grams per square metre, and water it in.

All lawns need good drainage and oxygenation, so scarify it with a springtine rake to remove thatch - dead grass that mats beneath growing grass - and moss. For larger lawns it's worth renting a petrol-driven lawn scarifier to do the same job.

If you have lots of moss it's worthwhile applying a moss killer before you scarify and wait a few days before raking it up.

Next, you need to improve badly draining soil by aerating the lawn, driving a garden fork into the ground all over the lawn when it is moist, making holes to a depth of 10-15cm (4-6in). I once bought a pair of lawn aerating shoes, but they kept falling off so I went back to the old faithful fork.

Others use hollow-tine lawn aerators which remove plugs of soil from the ground, but they are hard work and aren't very good on stony soils or heavy, dry soils.

The holes you make allow air and water to get into the grass roots and should then be filled with a mixture of sharp sand and organic soil conditioner to stop the holes from closing up.

Some lawn dressings incorporate a slow release fertiliser but if this isn't the case, add a little amount of general lawn fertiliser (not containing weed or moss killer) before applying it. Make sure you brush it evenly over the area or it will become patchy when the fertiliser kicks in.

A few weeks later, if your lawn is still patchy, oversow it lightly with a quality lawn seed.

By summer, you should be mowing weekly, stepping up to twice a week when necessary, but don't mow the grass shorter than 2.5cm (1in) high and keep on top of weeds in the lawn. Annual weeds which emerge in any bare patches will be removed by mowing.

If your lawn still looks sickly after a few months of TLC, a number of organisations provide free soil analysis, including GardenAdvice.co.uk, or a free 14-point lawn analysis with TruGreen on 0116 275 9000 or log onto www.trugreen.co.uk