Lawn Renovation Time

Wednesday, 16 August 2017 | Gardener Expert
Posted in Garden Trader Blog, Gardening Advice

Lawn Renovation Time

Ideally you should have been mowing your lawn on a regular basis, weekly would suffice or better still twice weekly.

A couple of weed and feed applications throughout the growing period would have helped keep unwanted weeds at bay and stimulated some healthy growth.

Most lawns however, after a long summer of growth and use, will be prone to some physical damage, loss of grass cover, pest damage, compaction and die back. The biggest contribution to achieving a decent lawn the following season is by carrying out an end of season renovation of your lawn in late August early September.

A visual examination of the surface is simply not good enough, taking a number of core samples allows you to see the amount of thatch, root density and integrity of the soil, in terms of having any root breaks or changes of soil physical properties. Ideally you should be taking core samples to a depth between 100 mm – 150 mm.

These soil samples will help determine what work needs to be done, get them analysed for soil nutrient status, soil pH and if you really want to understand what soils you have get a particle size analysis done.

The aim of our renovations is to remove any underlying thatch material (dead grass/organic matter content), de-compact the soil, top dress to restore levels and re populate with new grass seed.

The first job is to clean off as much vegetation as possible and remove any unwanted organic matter/thatch by the process of mowing, scratching, scarifying and sweeping the surface prior to topdressing.

Thatch is a tightly intermingled layer of living and dead stems, leaves and roots which accumulates between the layer of actively growing grass and the soil underneath. Thatch accumulates when the production of dead organic matter exceeds the rate at which it decomposes.
Scarifying is a process perhaps best described as a mechanical raking. Although its primary purpose is to remove thatch, it has associated benefits as well (linear aeration).

Scarification is important to remove unwanted vegetation, but also to produce a key for the new top dressing material and seed to sit in. The level of scarification required will be dependent on how much of a thatch layer you have generated throughout the growing season, scarifying in at least three directions.

Once you have scarified your lawn and removed the unwanted debris, you are then ready to de-compact the lawn by carrying out some aeration work, either by hand using a fork or by hiring a decent punch type solid tine spiker, aerating to a depth between 50 – 100 mm.
If you have drainage problems and have standing water, you may want to consider some deeper aeration by hiring in a deeper solid tine spiker that can penetrate to a depth of 150 – 200 mm.

It will then be a case of top dressing the lawn with a screened sand/soil rootzone to restore levels and oversowing with suitable grass seed mixture; do not be frightened to try out new cultivars.

Sowing rates now range between 35 – 50 g/m2. In essence, you are aiming to establish new grasses into your lawn.
Aim to complete all renovations by the end of October at the absolute latest, and preferably sooner, ryegrass needs a soil temperature of above 5.5OC in order to germinate. With favourable temperatures, the seed should germinate between 7 and 14 days. Water the seed if necessary and keep moist until the grass plants have established.

A pre-seeding NPK fertiliser can be used to help promote some growth, something like an 8:12:8 or even a 7:7:7 at 35 g/m2 will be ideal, though you should be careful not to use anything with iron in at this stage as it can acidify the surface and damage the new grassplants. It will then be a case of allowing it to grow to a height of around 40 mm before giving its first cut using a rotary mower.

Regular mowing when the grass is growing will maintain the sward health. Certainly, do not allow the sward to grow above 50 mm when established or else there will be a loss in density.

Feed through the winter months too! Grass needs much less nitrogen through the winter months, but that does not mean that it needs none. Applying a low nitrogen feed, which is high in potassium, will help the grass plant recover from damage and stress and keep red thread at bay.