Off-the-shelf feed and weed grass care is okay, but air is best answer

DO you ever find yourself stealing glances over the fence and wondering just how your neighbour manages to get their grass so green? Well, the answer could quite simply be right under your nose: air.

It is easy to spend a considerable amount of money on off-the-shelf weed and feed lawn care products and moss killers, when an injection of air may be all your grass is craving.

Aeration is the process of letting air into the soil and at RHS?Garden Harlow Carr, it is an important part of our annual turf maintenance programme. It is also something that can be undertaken on your lawn at home and will have immediate benefits.

Over time lawns build up a layer of thatch as dead leaves and organic matter build up between the soil and the grass plant. This starts to form an impermeable layer, preventing water and any nutrients reaching the soil underneath.

The soil can also become compacted due to usage, particularly after the amount of rain that we have had recently. The air spaces between the soil particles disappear, meaning that essential nutrients that are stored in the soil can’t then reach the grass roots; carbon dioxide gets trapped in the soil and the roots have nowhere to grow.

To counteract all this we need to force air back into the soil and the best way to do this is hollow coring, where 4in vertical plugs of soil are taken out of the turf at regular intervals. The holes are then filled with a top-dressing of loam, sand and well-rotted organic matter in order to correct surface irregularities and improve the texture of difficult soils. Another effective method is tining (spiking), where solid tines are forced into the ground to make holes.

Both methods penetrate the thatch layer allowing air and water to flow into the soil. The microbes already present in the soil are stimulated into breaking down the thatch. The grass plants will become healthier as their roots have space to grow and establish; water and nutrient flow is improved, meaning plant uptake of both is better; the trapped carbon dioxide can flow out of the soil to be replaced with oxygen, increasing air spaces between soil particles; the soil becomes less compacted and drainage will improve. Basically, it lets your lawn breathe.

One of the simplest ways to do this at home is to use your garden fork to go over your lawn, spacing holes 10-15cm (4-6in) apart and deep. For larger lawns or on clay or waterlogged soil you can hire hollow corers or tining machines. Aeration every two to three years for an average lawn should be adequate, but areas that receive the most wear and those that are compacted will need more frequent attention; you cannot over-aerate.

Early May is a great time of year for aeration as the soil is still moist, grass is actively growing and it should encourage a healthier growing season over summer. If we are lucky enough to enjoy a hot summer this year you may need to water your lawn slightly more often: as the drainage will be improved, it will also dry out quicker.

The other optimum time is September whilst the grass is still growing. Your soil may be slightly harder then but it will allow time for the grass to respond before the dormancy over winter. Whenever you decide to aerate, your grass will be breathing a sigh of relief!

Jobs to do this week

Watch out for late frosts. Protect tender plants

Earth up potatoes, and promptly plant any still remaining

Plant out summer bedding at the end of the month (except in cold areas)

Collect rainwater and investigate ways to recycle water for irrigation

Regularly hoe off weeds.

DIARY DATES

Until May 29: Bath House Gallery – Art & Photography Showcase

Whether you like traditional oils and watercolours or modern photography, there will be a wide choice of styles to choose from including work by regulars such as Teresa Boast and Nikky Corker alongside artists exhibiting for the first time. Normal garden admission.

May 14 to 15: Rhododendron Show

Competitors from across the north of England will showcase the very best camellias, magnolias and rhododendrons the region has to offer at this popular two-day annual show. The Harlow Carr Rhododendron, Camellia and Magnolia group will be on hand to offer advice and expertise and will celebrate the garden’s beautiful collections of rhododendrons during special woodland walks. Normal garden admission.

Events at RHS Garden Harlow Carr are free with the normal garden entrance fee, except where stated.