Overseeding the lawn

Overseeding of an established lawn is an essential task in a lawn care program, it is carried out annually. The optimum time of the year for overseeding is late summer early autumn.

However overseeding is often undertaken in spring particularly if the lawn has been left thin and weak following moss killing treatment and removal.

What type of seed you choose for overseeding will be dictated by your lawn requirements and the environmental & climatic conditions that apply to your site.

As a result by understanding these factors will enable you to choose the correct seed for you lawn ultimately leading to a healthier sward.

Why overseed a lawn

There are numerous reasons why you might want to overseed your lawn.

• Improve the lawn characteristics such as shade tolerance, drought tolerance, disease resistance by selecting the correct mixtures for your requirements.
  
• Repair the lawn and increase the sward density after renovation has left the lawn looking thin and weak.
  
• Encourage finer grasses such as bents and fescues if your goal is to have a fine luxury lawn.
  

What is the ideal time for overseeding a lawn

The best overseed a lawn is during the late summer/early autumn period as part of the autumn renovation program, after scarification and aeration have been carried out.

However it is important to do these tasks when there is plenty of growth left, this gives the seed time to establish.

It can also be undertaken in the spring time after moss removal, again after scarification has been carried out. However the autumn period is proffered because:

• The soil is warmer in the autumn which encourages better grass seed germination. In the spring the soil temperature can still be quite cold. This is not ideal for grass seed to germinate and can lead to very poor results. The last couple of springs are examples of this, where it has been slow to warm up with very mixed results regarding grass seed germination.
  
• Generally speaking there is more chance of rainfall and less chance of a drought later in the autumn.
  
• After the autumn program has been completed the lawn receives little or no maintenance or disruption (such as chemical weed killer applications) which can hinder grass seed establishment.
  

How to overseed the lawn

Overseeding is best carried out after aeration and or scarification as both of these operation encourage the seed to come into contact with the root zone which helps with germination and establishment.

Prior to overseeding mow the lawn a little shorter than normal, this helps the seed make contact with the soil and will also make the following task of top dressing a little easier.

Spread the seed to the lawn, ideally using a spreader. Apply the seed at the manufactures recommended rates for overseeding this is usually between 10-25g/m2 depending on the grass seed mixture.

The next task is to top dress the lawn, working it in to the sward with a brush or lute. This will help protect the seed and may also help retain some moisture for the seed.

Overseeding aftercare

After the program is complete it is important to keep the soil moist to encourage germination.
keep off the area as much as possible.

If the lawn has not been fed recently it would be beneficial to the new seedling to apply a suitable feed. Feeding after germination is more beneficial than it is prior to overseeding.

Feeding after germination helps reduce competition from the existing grasses. N. b. When applying fertiliser to new seed it is important that it is applied correctly and at the correct application rate.

Mow the lawn as normal raising the height of cut a little, just make sure that the blades are sharp so that they cut the grass cleanly (blunt blades tear and pull at the grass causing damage). Allowing the new seedling to grow too long before mowing them puts them under unnecessary stress.

Tips for successful overseeding

Overseeding into an already established lawn can prove quite difficult. there are several factors that can have a bearing on how successful you program will be. These are:

• Soil compaction: New seedlings will find it difficult to establish on a soil suffering from compaction as root development will be impeded, the soil will oxygen, drainage will be poor, all to the detriment of seed establishment. This can be remedied by suitable aeration prior to overseeding.
  
• Excessive Thatch Accumulation: Sowing seed into a layer of thatch is most likely going to yield poor results. Although the grass may well germinate it will find it difficult to establish and results will be poor. ideally seed needs to be in contact with the root zone for optimum results, this is difficult to do with excessive thatch. If thatch is a problem, a removal program prior to overseeding by scarification would be beneficial. Scarification also leaves a nice seed bed to aid germination.
  
• Soil temperature: Grass seed needs a warm soil for successful germination, overseeding when the soil temperatures are too low will most likely yield poor results. This is the main reason why overseeding later in the season is preferred to spring time.
  
• Soil moisture content: Grass seed needs moisture to germinate and establish. Aim to keep the soil moist, not too wet or too dry.
  
• Using the correct mechanical operations prior to overseeding: As previously mentioned scarification and to a lesser degree aeration help to create a seed bed which will help with seed germination.
  

Read More

Lawn Fertilizer

Both new and established lawns require a balanced fertiliser program to maintain good health. A lawn fertiliser contains nutrients, each nutrient plays an important role in the health of the grass plant. On almost all lawns the nutrient levels will be less than ideal.

Nutrients can be also washed through the soil (leaching) as well as being removed through grass clippings each time we mow the lawn. Therefore a lawn will require additional nutrition to be added periodically throughout the year.

A balanced lawn fertiliser program will ensure that your lawn remains in tip top condition. A healthy lawn will suppress lawn weeds and disease and will also be better able to withstand adverse conditions such as drought, wet and frosty conditions.

A balanced lawn fertiliser will include 3 key nutrients, these are nitrogen, phosphorous and potassium. Each of the nutrients plays a key role in a healthy grass plant, if any are deficient the health of the lawn will suffer.

We will take a closer look at the role of each of these nutrients has on the lawn.

• Nitrogen - This is the most important nutrient used on lawns and turf. The main role of nitrogen is to create plant growth and it gives the turf it's rich green colour. Nitrogen is applied to the lawn during the growing season as part of a spring / summer fertiliser (April - August). It is not used in large quantities during the autumn and winter as it can cause problems with lawn & turf diseases such as fusarium.
  
  
• Phosphorous - Phosphorous is important for a healthy root system on the lawn. It can be applied any time of the year but is predominantly used late in the growing season in an autumn / winter fertilizer.
  
  
• Potassium - Potassium is responsible for hardening up the grass plant and will help discourage disease and withstand drought conditions better. Again it can be applied any time of the year, with the spring and autumn being preferable times for application. AS we previously touched upon there are two different types of fertilizer formulations used on lawns, these are spring / summer and autumn / winter fertilizers.
  

When to apply lawn fertiliser

Spring & summer fertiliser. This lawn fertiliser is used at the beginning and during the growing season to encourage and maintain good, consistent growth when it is most needed. This helps maintain a good, thick, healthy lawn which will help suppress weeds and help the lawn withstand drought.

A spring/summer feed will contain a high percentage of nitrogen with smaller amounts of phosphorous and potassium. It may also contain some iron sulphate for moss control and a selective weed killer for weed control.

Autumn & winter fertiliser. This fertiliser is applied late in the growing season during the autumn. An autumn/winter feed contains a high percentage of phosphorous and potassium with very little nitrogen. The purpose of this lawn fertiliser is to keep the lawn healthy during the winter and into the following spring.

Slow release lawn fertiliser
Lawn fertilisers are available in both conventional form or slow release form. There are advantages with slow release fertilisers and lawn feeds.

• Longevity - Slow release fertilisers last longer, therefore fewer applications are necessary over the course of the year.

• Consistent growth - Grass growth is more consistent with a slow release fertiliser, there is no sudden flush in growth. A conventional lawn fertiliser tends to encourage a quick growth spurt then tails off before another feed is needed.

• Lower scorch risk - When a slow release is applied the risk of scorching the grass is reduced.

The main disadvantage with a slow release fertilizer is they are more expensive than conventional lawn fertilisers.

Granular or liquid lawn fertiliser

Lawn fertiliser is available in both granular or liquid formulations. With each type of fertiliser comes advantages and disadvantages.

• Granular fertilisers - Granular fertilisers can be applied by hand or by spreader. Although initial response after application maybe slower than a liquid, it will last longer requiring fewer applications.
  Granular fertilisers also require watering in thoroughly after application to eliminate any scorch damage to the turf or lawn.
  
  
• Liquid fertilisers - Liquid feeds can be applied by a watering can or a suitable sprayer such as a knapsack. Liquid feeds work quicker than granulars but they do not last as long.
  
  Liquids are generally safer to apply as there is less risk of scorch than with a granular feed.
  

However it is important to follow the manufacturers instructions when applying any type of fertiliser. If they are not applied correctly they can cause damage to the lawn or turf.

Read More

Top dressing the lawn

What is top dressing and why top dress the lawn

Another important task in any lawn care program is that of top dressing your lawn, especially if you desire or already have a luxury lawn.

Top dressing is the process of applying a layer of suitable material such as sand, soil and peat to the surface of the lawn. Top dressing the lawn on a regular basis has many benefits which include:

• Smoothing out any minor undulations or hollows on the surface of the lawn.

• Encouraging finer, more desirable grasses such as bents and fescues. Bents and fescues being the preferred grasses for fine turf luxury lawns.

• Top dressing the lawn encourages the grass to produce side shoots, resulting in improved sward density and a healthier lawn.

• Helps to control and dilute the thatch layer in the lawn.

• Improves the drought resistance of the lawn.

• Reduces water logging and helps with the drainage of the lawn.
  

Materials used for lawn top dressing

There are 3 main materials primarily used for lawn top dressing, these being sand, loam and peat. Each of these materials have there own benefits to the lawn.

We will have a look at these top dressing materials in more detail:

• Sand - Choose a lime free sand of medium particle size, avoiding course and particularly very fine particles. It is important that the sand is lime free (a sand that contains a high lime content can cause problems with worms, disease and weeds). Sand helps with the drainage on a lawn.

• Loam - Use a quality loam that is friable and does not contain a high percentage of clay. This can be purchased from most good garden centers. Loam contains an equal amount of sand, silt and clay, a sandy loam is arguably the ideal growing medium for a luxury lawn.

• Peat - a good quality sphagnum or sedge peat would be ideal for the top dressing mixture. Peat will help with moisture retention on lighter, sandy free draining soils.
  

How much of each material you apply to your lawn will depend on the root zone or soil that your lawn is constructed upon. E.G. A lawn on a light sandy soil will probably suffer from drought problems during a dry summer.

Therefore in this case you would require a top dressing containing a high proration of loam and peat and very little sand to help with moisture retention. A lawn that has a high clay content would require a higher percentage sand to help with the drainage.

For a quick guide on what mixture to use on your lawn the table below can be used as a reference. Note This is only a guide and the mixtures are not set in stone.

• Sandy soil - 2 parts peat, 4 parts loam, 1 part sand

• Heavy soil - 1 part peat, 2 parts loam, 4 parts sand

• Loamy soil - 1 part peat, 4 parts loam, 2 parts sand
  

When to top dress a lawn

The most common time of the year to top dress a lawn is late summer / early autumn. However it should be noted lawns can in fact be top dressed anytime during the growing season from April to October.

Lawn top dressing should be included in the autumn renovation program and is sometimes incorporated in the spring renovation program too. Top dressing is often applied after scarification, aeration and overseeding operations have been undertaken.

How much top dressing too apply to a lawn

When applying a top dressing to a lawn there is no set application rate. Top dressing rates can vary anywhere between 1.5kg to 4kg per square meter. The heavier rates would be used during the spring and autumn programs after scarification and or aeration has been completed.

Lighter rates would be used during the growing season when there has been less disturbance to the lawn and recovery is not as critical.

How to top dress the lawn

If part of the autumn of spring programs the top dressing will be applied after the lawn has been scarified and or aeration and or overseeding has been completed.

Choose and dry day and ensure both the top dressing and surface of the lawn are dry. Mowing the lawn prior to application will help make the top dressing operation easier, especially when brushing in the material.

Tip equal size heaps of top dressing on the lawn ready for spreading. The top dressing can now be spread as evenly as possible over the lawn, using a shovel. If your lawn covers a large area, powered spreaders are available for hire for this task.

The top dressing should be left to dry out completely, before rubbing it into the sward. You can use a purpose built tool like a true lute, brush or drag mat for this task, or alternatively the back of a rake or flat board on a wooden shaft will suffice.

Ideally leave the lawn a few days before mowing and if possible raise the height of cut on the mower to avoid picking up any of the top dressing material.

Read More

Scarifying the Lawn

Lawn scarification or dethatching as it is also known, is the process of removing thatch or organic matter by mechanical means using a powered machine called a lawn scarifier or lawn de-thatcher.

Over a period of time, lawn thatch or organic matter will slowly accumulate in the base of lawn, this is especially true on neglected lawns that receive little or no maintenance. When this accumulation of organic matter becomes excessive it needs removing, or the health of the lawn will suffer and start to deteriorate.

A lawn scarifier or dethatcher is a powered machine that consists of vertically mounted knife like tines or wire rake type tines. These tines spin and penetrate into the grass sward and remove unwanted debris or thatch.

Alternatively a hand held spring tine rake can be used but will not remove the amount of debris as a powered scarifier. Hand scarification is also very hard work and only really suitable for small lawns unless you want a good workout.

Deep scarification can leave a lawn looking thin, therefore it is important that it is undertaken during periods of good consistent growth. Avoid this operation during periods of drought or cold weather where recovery will be slow.

Why scarify a lawn

There are numerous reasons why a lawn might be scarified

• As we have previously touched upon lawns are primarily scarified to prevent or remove the build up of thatch. The disadvantages of thatch can be found in more detail on the lawn thatch page.
• Scarifying is also carried out in the spring time (as part of the spring lawn care program) to remove moss from the lawn after treatment. Moss is most prevalent during the springtime and may people apply a moss killer to kill it off. After the moss has died it should be removed in the form of raking or scarification before moving on to the next task.
  
  
• The most intense scarifying operation is carried out during the late summer as part of the autumn renovation program. This scarifying operation creates a nice seed bed prior to overseeding and is very important in the successful establishment of the seed. This is because intense scarifying helps bring the seed into contact with the root zone or soil beneath the surface of the lawn.
  
  
• Light regular scarifying operations during periods of strong growth in the summer can prevent thatch build up and remove any unwanted lateral growth. This gives the lawn a very tidy, cared for look just when you want the lawn to look it's best during the summer months.
  

Scarifying helps keep the lawn in a healthy condition by keeping the thatch layer in check. A lawn that has excess thatch will have poor drought tolerance, poor drainage and weak grasses that suffer from wear.

When to scarify a lawn

Lawns can in fact be scarified any time during the growing season providing suitable conditions apply. However the most common times are spring and late summer or early autumn.

Scarifying in the spring time is often carried out after any moss control or treatment. Scarifying removes the moss from the lawn once it has been killed. It is important not to scarify to early in the spring when there is little growth, wait until there is sufficient growth to aid a speedy recovery.

The ideal time and most intense lawn scarification is undertaken late in the growing season (late August - early September) as part of the autumn lawn care program. Again it is important to complete the program whilst there is still sufficient growth for the lawn to make a full recovery.

Light scarifying (often called verti-cutting or grooming) can be undertaken during periods of strong growth during the summer. This helps to prevent any thatch build up and prevents any lateral growth and keeps the lawn looking tidy and cared for.

Read More