Lawn care in summer

How to water your lawn when temperatures are high

If you want to keep a lush green lawn all year round, then watering your lawn is an essential maintenance measure, particularly in summer when there is often little natural rainfall. As a rule of thumb for lawn care, you need to supply enough water to penetrate at least 25mm into the ground approximately once a week – depending on sunlight, heat levels and wind.  

Do I need to water my lawn in summer?

In summer when there is little to no rainfall, your lawn may turn brown and appear lifeless.  Don't worry, for a well established lawn this does not mean that it is dead.  Grass is incredibly resilient and will go into a dormant state in times of drought.  Once rain returns, new leaves will grow and it will recover very quickly - only new lawns need to be watered regularly in order to survive a dry spell.  If water is in short supply prioritise the plants that really need it and use stored rainwater or 'grey water' to save the mains supply.

How much water does my lawn need?

If you’re new to gardening, you’ll need to use more than you probably expect.  The amount of water your lawn needs will depend on multiple factors such as the species of grass or type of soil.  However, it’s important to remember that overwatering your lawn can also be harmful, as it forces air out of the soil, which can cause root rot. Take a sample from your soil and have a sniff of it: if it smells bad or is grey-blue in colour, it’s highly likely to be waterlogged, suffocated and in need of care.  Also, do not be tempted to water your lawn more if it is brown - this means it has already entered into a dormant state and you will likely waste water and do more damage than good.

Checking the moisture of your lawn

In a dry summer, make it a part of your lawn care routine to check that the lawn is getting enough to drink. If you don’t have a moisture meter to hand, you can check by placing several jam jars in various locations around your garden. There should be around 2 cm of water in all the jars after rain or watering if the grass has received enough. From this, after some trial and error, you will be able to gauge water needs perfectly so your lawn need never be stressed by the summer heat.

Another method is to insert a strong blade or spade into the ground to extract a soil sample to a depth of around 10 cm in several places. In a well-watered lawn, the deeper soil should be damp (not wet), and the top 1 to 2 cm should feel dry – it should never be the other way around. If the sample is damp on top and dry underneath, the water is not getting to where it’s needed.

Common mistakes in summer lawn maintenance

When it comes to watering in summer, the most common mistake is doing it both too often and not deeply enough. Many people have a schedule for lawn care that involves giving their lawn a light watering every evening during the heat of summer, but this causes longer-term problems. That’s because it's mainly lawn thatch that gets dampened if you do this, along with just the top few millimetres of soil. Over time, the grass responds by concentrating its roots close to the surface of the soil, making it particularly vulnerable to summer stress. Another effect is that lawn thatch will quickly build up and start to dominate because it prevents moisture from reaching the soil underneath, so the lawn keeps drying out. The lawn is now unhealthily 'addicted' to moisture, and after just a few summer days of not watering, it will quickly turn yellow and need extensive care, as well as being much more susceptible to fungal diseases.

When to mow your lawn in summer

Your grass is at its peak in early summer as it emerges from spring bursting with strength and new growth. That means your lawn care schedule may need to include more frequent mowing, roughly every four to seven days. In fact, regular mowing encourages your lawn to grow more densely by stimulating the grass to develop new side shoots – though keeping the grass at the right height is actually more important than the frequency of mowing.

What lawn height is best in summer?

The higher the temperatures, the longer the grass should stay to protect the sensitive blades. Mow the lawn at 2.5 to 5 cm in sunny areas and 5 to 7 cm in the shade. If a heatwave is coming, you can leave lawn that is exposed to the sun at a longer length so that the blades shade each other. As a general rule, no more than a third of the length should be shortened each time you mow to avoid burns and blemishes in the lawn. Always use sharp mower blades and make sure the ground is dry.  In summer it is a good idea to let the grass clippings go back into the lawn rather than collecting them, as this allows the ground to retain moisture and returns vital nutrients to the soil.  This technique is known as mulching and if you don't already have a mulching mower, you can easily convert many of our standard mowers into one with a STIHL mulching kit.

How to feed your lawn in summer

By the start of summer, the nutrients from a spring fertiliser application have almost been used up. To best care for your lawn through energetic football matches and barbecues, we recommend you fertilise again at the start of summer. In fact, even lawns that don’t see this sort of traffic can benefit from a vitamin boost, as frequent early-season mowing means many of the nutrients in the grass will be lost in the cuttings, which puts a lot of strain on the soil in the long term. That’s why it's so important to return vital nutrients to the lawn in summer, and the best way to do it is by applying a mineral lawn fertiliser.  Alternatively, you could consider mulching - leaving your grass clippings in the lawn instead of collecting them - this acts as a natural fertiliser and helps the lawn to retain moisture.

The right summer lawn fertiliser

When choosing the right fertiliser for your summer lawn treatment, it needs to contain these essential ingredients for keeping your soil and lawn healthy:

It’s important for these minerals and nutrients to be present in the appropriate concentration. Alongside plenty of nitrogen for growth, magnesium and calcium are required at higher levels to make sure your lawn can withstand extreme heat and summer storms.

Lawn care tips for feeding your lawn in summer

• Get the feeding in early. You should ideally fertilise your lawn in June to prepare it for the hot summer ahead.
• Promote dense growth by using slow-release fertilisers; the grass grows slowly through the summer but becomes thicker and more resilient.
• Use a sprinkler system – this makes it easy to water the lawn generously but carefully after fertilising.

Summary: Lawn care in summer

• Water liberally once a week, enough to penetrate the soil at least 25mm..
• Flattened patches of lawn may indicate dehydration.
• Take care to regularly check your lawn’s moisture levels and adjust watering accordingly.
• If your lawn continues to grow throughout the summer, mow it once a week, reducing the length of the grass by no more than a third each time. Sunny lawns should be between 2.5 and 5 cm high. During strong heat waves, the lawn can also be slightly longer.
• Shady lawns should have a minimum height of 5 cm.
• Consider fertilising your lawn in June to prepare it for peak summer heat, or mulch instead.