Lawn care in summer

Whether the summer brings a heatwave or a downpour, your lawn has a lot to contend with. We show you the most effective ways to protect it.

A man is halfway through mowing untidy and overgrown grass using a STIHL RMA 448 P-C cordless lawn mower, in a garden surrounded by tall shrubs and plants

How to water your lawn when temperatures are high

Watering your lawn is one of the most important maintenance measures to consider all year round, and particularly in summer when there is often little natural rainfall. As a rule of thumb for lawn care, you need to supply approximately 20 to 25 l of water per square metre per week – depending on sunlight, heat levels and wind.

How much water does my lawn need?

If you’re an amateur gardener, you’ll need to use more than you probably expect. In general, lawn maintenance in summer means supplying each square metre of your lawn with 20 to 25 l. However, it’s important to remember that overwatering your lawn can also be harmful, as it displaces air from the pores in 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.

Close-up of a well-cared-for green lawn in sunshine

Tips for watering your lawn in summer

  • Once a week is enough for watering in your summer lawn care schedule, using approximately 20 l of water per square metre each time. This amount should be varied to account for the specific site and weather conditions.
  • Clay soil: clay-rich soils are prone to baking hard in summer, so may need a little additional care. If your soil cannot absorb the full volume given in one go, water more lightly but twice in quick succession (or on the next day), and then don’t do it again for a week.
  • Make sure you are watering evenly. When taking care of your lawn, the last thing you want is for summer heat to cause dry patches – you can use a soil moisture meter to check that the lawn is sufficiently hydrated all over.
  • Do your watering in the early morning or late evening, as strong, direct summer sun can scorch a damp lawn.
  • If you have trees, shrubs or hedges growing around your lawn, increase the amount of water you give it.
  • In the extreme heat that can occur at midsummer, your lawn needs extra care: increase your watering frequency to two to three times a week, in the early morning or in the evening.

Checking the moisture of your lawn

In a dry summer it becomes an even more important part of your lawn care routine to know that the lawn is getting enough to drink. If you don’t have a moisture meter to hand, you can check by placing a number of jam jars in various locations in 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, and you can give it the right care just when it needs it.

Another method is to insert a strong blade or spade into the ground to extract a sample of soil to a depth of around 10 cm, in several places; in a well-watered lawn, in summer 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 frequently and insufficiently deeply each time. 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 is mainly lawn thatch that gets dampened if you do this, along with just the top few millimetres of soil in the best-case scenario; 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 any 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.

A woman using a STIHL RMA 339 C cordless lawn mower to cut grass with wooden fence and log store in the background

When to mow your lawn in summer

Your grass is at the top of its game in early summer as it comes out of spring, and so it will be bursting with strength and growth. That means your lawn care schedule can certainly include mowing every four to seven days when summer begins. In fact, such 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 4 to 5 centimeters in sunny areas, 5 to 7 centimeters in shady areas. If a heat wave is foreseeable, the lawn can also be left in the sun a little longer so that the blades shade each other. As a general rule, no more than a third of the length should be shortened per mowing operation to avoid unsightly burns and blemishes in the lawn. Always use sharp mower blades and ensure that the ground is dry.

Grundstück mit Baumhaus, Gartentisch und Stühlen und grünem Rasen

What can I do about indentations on the lawn?

Particularly in summer, if blades of grass do not automatically stand up again after being walked on this can indicate dehydration. Take a look at your watering routine, and consider a weekly schedule using 20 to 25 l for each square metre.

How to feed your lawn in summer

By the start of summer, the nutrients from the spring fertiliser application have almost been used up. To best care for your lawn through the season of boisterous 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 right now, 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 is 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.

The right summer 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:

Active ingredient Description
Potassium (K) Increases pest resistance, regulates plants’ metabolism
Phosphorus (P) Strengthens root growth and helps to protect against frost
Magnesium (Mg) Supports chlorophyll formation during photosynthesis and ensures that the lawn is a vibrant green colour
Calcium (Ca) Stabilises the cell walls of the grass and helps the plants to absorb nutrients from the soil
Nitrogen (N) Encourages cell division and therefore the regeneration of all parts of the plant. Stimulates lawn growth

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 ensure that your lawn can withstand both 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; with these, 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, at a rate of at least 20 l per square metre
  • Flattened patches of lawn may indicate insufficient hydration
  • Take care to regularly check your lawn’s moisture levels and adjust watering requirements accordingly
  • Mow your lawn at least once a week in summer, reducing the length of the grass by a third each time. Sunny lawns should be between 4 and 5 centimetres high. During strong heat waves, the lawn can also be slightly longer.
  • Shady lawns should have a minimum height of 5 cm.
  • Fertilise your lawn in November to prepare it for peak summer heat