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How much grass seed do I need for a new lawn from seed?

When it comes to establishing a new lawn from scratch, it’s essential to calculate the correct amount of grass seed needed to ensure a successful and healthy lawn. To determine the quantity of grass seed required, several factors need to be taken into consideration.

Firstly, measure the square metre area of the lawn where the grass will be seeded. This will provide the base value for calculating the amount of grass seed needed. Different types of grass have specific seeding rates, so it’s crucial to choose the most suitable grass for your lawn and follow the recommended seeding rate.

Factors to Consider When Calculating Seed Needs

When planning to seed a new lawn, there are several factors to consider in order to determine how much grass seed you will need. These factors include the size and shape of the lawn, the type of grass you wish to use, the existing soil conditions, and any special features or challenges in your garden. By taking these factors into account, you can ensure that you purchase the correct amount of grass seed and achieve the desired results for your lawn.

First, determine the square meter area of your lawn by measuring its length and width and multiplying these dimensions together. If you have a circular or irregularly shaped lawn, break it down into smaller sections (rectangular or triangular) and calculate the square footage for each section separately. This will help you accurately estimate the total amount of seed needed. To make this easier, try using our grass seed calculator which will work out how much seed you need for a square lawn, rectangular lawn,  triangular lawn or circular lawn.

Next, consider the type of grass you want to grow. Different grass types have varying sowing rates, with some requiring more seed per square meter than others. It is important to choose a grass variety that is suitable for your climate, soil type, and usage requirements. All of our grass seed mixes give details of the sowing rate in the product description, see below.

Existing Soil Conditions

The existing soil conditions also play a role in determining seed needs. If you have poor soil quality or excessive weed growth, you may need to overseed or use more seed to achieve a dense and healthy turf. Additionally, if you have a shady lawn or have special features such as slopes, these areas may require more seed for optimal coverage and growth. In such areas it is advisable to increase the sowing rate by up to 50% to allow of the fact that germination rates will be lower.

Consider the soil contact as well. Good seed-to-soil contact is essential for optimal germination and growth. Before seeding, prepare the soil properly by removing any debris, loosening it with a rake, and possibly applying a thin layer of topsoil or compost. Lawn seed needs to be loosley incorporated into the top 5-10mm of top soil, seed that is left on the soil surface will struggle to germinate and successfully establish.

By carefully considering the square metre area, type of grass, soil contact, ideal conditions, and lawn shape, you can accurately determine how much grass seed you need for a new green lawn. Following these calculations will assist in establishing a lush and beautiful lawn.

Grass Seed Sizes

How much grass seed you need depend on the type of grass species used. Different grass seed species have different seed sizes, small seed size requires less seed and conversely large seed size requires more seed. As a guide, in a single gram of seed you would typically find the following*;

Perennial Ryegrass (Lolium perenne) = 700

Red Fescue (Festuca rubra) = 1,000

Hard Fescue (Festucs trachyphylla) = 2,000

Browntop Bent (Agrostis capillaris) = 14,000

Smooth Stalk Meadow Grass (Poa pratensis) = 3,000

So with grass seed sizes in mid, it is important to adjust seed sowing rates accordingly to ensure the correct rate. With seed size for Browntop Bent being much smaller than Perennial Ryegrass, it makes sense that the the sowing rate for Browntop Bent is much less.

Can I sow grass seed to thick?

Sowing grass seed too thickly can lead to several potential issues for your lawn. While it might seem like more seed would result in a more dense turf, excessive seeding can have negative consequences.

When grass seeds are sown too closely together, they have to compete for resources such as sunlight, water, and nutrients. This competition can result in weak, thin grass as the plants struggle for survival. Overcrowded grass can lead to poor air circulation, creating a favorable environment for diseases like fungus.

Fungal infections are more likely to occur when the leaf blades are densely packed and air cannot circulate freely. A turfgrass disease that is likely to occur as a result of an exessive seed rate is Damping Off, which is caused by Pythium, Rhizoctonia, and Fusarium spp fungi. If this occurs there is little that can done, the best way to manage it is to avoid it in the first place.

How much grass seed to sow a lawn from scratch?

To get a healthy, strong lawn you need to get the correct sowing rate. As we have already mentioned, the sowing rate needs to take into account the different factors that will come into play. Things like soil temprature, air temperature and soil condition all come into play. But as a general rule for a  typical ryegrass and fescue seed mix a sowing rate of 25-35g/m2 is sufficient. At that rate a 20kg bag will cover anywhere from 570-800m2.

Something to take into account is seed quality. Often cheap lawn seed is cheap becuse it is old or has low germination. Grass Seed Onlineis part of a registered family seed business and we take pride in the quality of the seed we supply.

To accurately work out how much grass seed you will need, try out our grass seed calculator.

*Barenbrug Grass Variety Information