When to overseed your lawn in fall – for lush grass every summer

Learn when to overseed your lawn in fall for lush greenery summer after summer

Real Garden Dulwich. Grass lawn. Flower beds.
(Image credit: Annaick Guitteny)

Learning when to overseed your lawn in fall is an essential part of your yearly lawn maintenance, often making the difference between lush summer grass and unsightly patchy growth. 

When it comes to how to make a lawn green and thick, overseeding is an easy and relatively quick method to treat your entire lawn in one go, and, when coupled with the best fast-growing lawn seed and pest control, it is a surefire way to rejuvenate your lawn and improve the look of your backyard landscaping ideas.

Here, we have spoken to experts to learn when to overseed your lawn in fall for the best grass year on year. 

When to overseed your lawn in fall  

‘The fall months are the best time to overseed your lawn to bolster your backyard ideas,’ explains Rachel Crow, garden editor for Homes & Gardens. ‘Between late August and early October, the grass is typically at its thinnest, meaning grass seed can more easily reach the soil and germinate before the harsher, colder winter months.’ 

It is a good idea to choose a day with mild weather, preferably after rainfall, so your lawn is moist but not muddy. Selecting a day with little wind will also reduce the chance of your grass seed being blown away. 

‘The still-warm earth and natural rainfall that tends to arrive in September will help to nourish and stimulate the newly sown seed, as well as reduce the time you’ll have to spend watering or trying to beat any hosepipe bans,’ says Guy Jenkins consumer manager for Johnson’s Lawn Seed. (opens in new tab) ‘By waiting until later in the year you will avoid the summer droughts which spell death for tender young seedlings that haven’t managed to reach deeper groundwater. 

‘Another benefit of September is that any weeds which find their way into your newly sown lawn will have a chance to germinate and can be easily removed before their own roots have a chance to develop. In the meantime, your grass can grow strong roots in later autumn and will be in the best possible shape to withstand early droughts come the following spring or more serious summer droughts that might be on the cards,’ Guy adds.

A lawn at the back of a house with dark trees on the left hand side

(Image credit: Unsplash)

How to overseed your lawn 

If you know how to plant grass seed, the process is very similar. When overseeding, however, you will want to mow any existing grass to around one inch in length, as well as rake any thatched areas of grass. You will likely notice clues that your lawn is in trouble and may need overseeding, such as yellowing or thatching.

It is important to aerate the soil before spreading your lawn seed evenly across the area. Overseeding can be done across a small patch of dying grass or your entire lawn if required. You should aim to keep this soil moist in order for germination, so water for the first 21 days after planting. 

Flower and plant beds. Lawn, table and benches.

(Image credit: Future)

Why should you overseed your lawn?  

‘Overseeding of an existing lawn is an important part of lawn maintenance,’ explains Jonathan Hill from Rolawn (opens in new tab). ‘The effort you put in during the autumn months will improve the quality and health of your lawn well into the following spring and beyond. It will naturally thicken your lawn and improve the lawn's overall appearance and resistance to pests.’

Overseeding a lawn is a great lawn repairing tip to fill in thin, bare patches, reduce weed and moss invasion, and bolster areas of high use such as where pets or children play, Jonathan continues.  

A cement pathway through a grass lawn, with large shrubbery on the left hand side

(Image credit: Unsplash)

Should I fertilize before or after overseeding?  

If your lawn has not been fertilized recently, it might be a good idea to lay a lawn starter fertilizer before overseeding. Adding fertilizer to your lawn will encourage germination by providing the right nutrients for initial growth. You will want to avoid standard fertilizer for established grass as this rarely has the nutrients needed for root development.  

Do I need topsoil when overseeding? 

When overseeding your lawn you do not need topsoil. Instead, consider laying compost or a lawn starter fertilizer to encourage growth and germination. You should also avoid laying topsoil over freshly laid seeds. Although this is through to protect the germinating seeds, it can smother them and make it difficult for young shoots to emerge. Preparing the soil with proper aeration is a better technique that allows for protection.  

Chiana Dickson
Junior Writer

Chiana is a junior writer for Homes & Gardens having joined Future plc as a new graduate in 2022 after achieving a 1st class degree in Literature at university. She first became interested in design as a child after spending her summers helping her parents redecorate her childhood home. As a long-time reader of Future’s homes titles, Chiana is constantly finding new inspiration at work as she focuses on emerging trends, how-to’s, and news pieces.