Lawn aeration: when, how often and how to do it right
Water stands on the lawn for a long time after rain, the soil is as hard as a path, the grass stays thin and quickly turns brown in dry weather. These are typical signs of compacted soil. Aeration opens it up again so that air, water and nutrients reach the roots. Here you will learn how to tell that your lawn needs it, when the right time is and how to proceed step by step.
In short
- Aerating with hollow tines pulls cores out of the soil and makes room for air, water and roots.
- The best time is late summer to early autumn, in spring only once the soil reaches about 10 °C.
- In a home garden once a year is usually enough, heavy and heavily used soils benefit from two passes.
- Mow as short as possible beforehand, then collect the cores, top-dress with sand and overseed if needed.
- After top-dressing, mow with a rotary mower for a few weeks, not with the reel mower.
What happens during aeration
When you aerate, tines are pushed into the soil. Hollow tines pull out small cores, with the Lawnpecker from a depth of up to 9 cm. The soil gets room, air reaches the root zone and water can drain again. If the holes are then filled with sand, they stay open as drainage channels for a long time.
There are two other tools with their own jobs: solid tines push the soil aside instead of removing it and loosen it deep down. Spikes open the surface quickly and can be used at short intervals. We explain the difference to scarifying, which removes moss and thatch at the surface, in Aerating or scarifying.
How to tell that your lawn needs air
| Sign | What is behind it |
|---|---|
| Water stands on the lawn for a long time after rain | compacted soil, the water cannot get down |
| A screwdriver can hardly be pushed into moist soil | dense soil structure, few pores |
| Thin grass on paths, play areas and corners | compaction from foot traffic |
| Moss is spreading | often a result of wet soil and lack of air, but also of shade or acidic soil |
| Water beads up after a dry spell | the soil has become water-repellent |
The right time
Aerate when the lawn is growing and the holes can close again quickly. The soil should be moist but not soaked. As a rule of thumb, the soil temperature should be above about 10 °C.
| Period | Suitability |
|---|---|
| Late August to early October | the best window: the soil is still warm from summer, moisture returns and overseeding germinates with hardly any weed competition. Finish at least about six weeks before the first frost. |
| Late April to May | well suited once the soil has dried off, is warm enough and the lawn is growing strongly |
| Summer in heat and drought | only as an exception, the open soil loses a lot of water and the lawn is under stress |
| Wet or frozen soil | do not aerate, the tines smear the soil or cannot get in |
Why late summer usually beats spring is explained in detail in Why September is the best month for lawn renovation.
How often should you aerate?
For a normal home garden one thorough pass a year is enough, ideally in late summer. Two passes, in spring and in late summer, pay off in three cases:
- Loam or clay soil: these soils compact much faster.
- Heavily used lawn: play areas, dog runs or areas with a lot of foot traffic.
- First treatment: soil that has been neglected for a long time benefits from both windows in the first year, after that one is usually enough.
In between you can open the surface with spikes, and in late autumn and winter loosen the soil deep down with solid tines. Neither replaces the pass with hollow tines, but both complement it well.
Step by step
1. Mow as short as possible
Mow beforehand as short as your mower allows and remove clippings and thatch. The tines go in more easily, the sand later trickles down to the soil instead of getting caught in the blades, and any overseeding gets light and soil contact.
2. Check the soil moisture
The soil should feel like a lightly wrung-out sponge. If it is dry and hard, water thoroughly one to two days beforehand. If it is wet and greasy, it is better to wait a few days.
3. Aerate
Work across the area in even, parallel lanes so that no strips are missed. A collection tray under the tines catches the cores straight away, so they do not fall back into the holes.
4. Collect the cores
Collect whatever has not landed in the collection tray. On light soils you can also crumble the cores and work them in. On compacted loam, however, that puts back exactly the soil you have just taken out.
5. Top-dress with sand
Spread dry, washed quartz sand with a grain size of 0.5 to 2 mm and pull it into the holes with the levelling rake. This evens out small bumps at the same time. As a guide, 3 to 5 litres per square metre are enough in a home garden. More on types of sand and quantities in Top-dressing your lawn with sand.
6. Overseed if needed
Overseed bare or thin patches straight afterwards, the open surface gives the seed good soil contact. With the drag mat you work in sand and seed in one go, alternatively press the seed down with a roller. Then keep the germination zone evenly moist. Details in Sowing a lawn.
7. Aftercare
For the first one to two weeks water regularly but not too heavily and walk on the area as little as possible. Feed according to the season: balanced in spring, potassium-rich and low in nitrogen in late summer and autumn. More in Eco-friendly lawn feeding.
Good to know
After top-dressing, put the reel mower aside for a few weeks. Sand grains on the surface quickly blunt the reel and bedknife. Until the sand has been washed in, mow with a rotary mower.
Which tine for which soil?
The heavier and more compacted the soil, the larger the diameter of the hollow tines can be.
| Tool | Suited for |
|---|---|
| Hollow tines 16 mm | follow-up passes and lighter soils |
| Hollow tines 20 mm | the all-rounder, also for the first treatment and compacted soils |
| Hollow tines 24 mm | loamy, wet and very hard soils, a lot of soil exchange when top-dressing |
| Solid tines | deep loosening without removing soil, especially in late autumn and winter |
| Spikes | quickly opening the surface in between, better than nothing |
Hollow tines are available as a 2-tine and a 3-tine plate. All attachments and what they are for can be found in Lawnpecker attachments.
Cables or pipes in the ground?
If shallow cables, pipes or a mole net lie in the ground, the adapter kit reduces the working depth of the hollow tines from 9 to 6 cm.
Common mistakes
| Mistake | Better |
|---|---|
| Aerating in heat and drought | wait until late summer or water thoroughly beforehand |
| Working on long grass | mow as short as possible beforehand |
| Leaving cores on loam | collect them, fill the holes with sand |
| Leaving the holes open | top-dress straight away, otherwise they close with the next rain |
| Using the reel mower after top-dressing | use a rotary mower for a few weeks |
| Nitrogen-rich feeding in late autumn | use a potassium-rich fertiliser |
Frequently asked questions
Can I aerate a young lawn?
On a new sowing only once the turf has closed completely and can take load, depending on seed and conditions after about a year. Before that the tines tear out too much.
Do I have to scarify before aerating?
No. If the lawn has little thatch but water drains poorly, aeration is the more direct measure. Scarifying is only worthwhile with a firm thatch layer or a lot of moss.
When will I see a difference?
On warm soil usually after four to six weeks: the lawn becomes denser and water soaks in better. On heavy soils the structure changes over several passes.
Does aeration make sense after a dry spell?
Not during acute heat. As soon as temperatures drop, however, it is particularly important, because dried-out soils often become water-repellent and only take up rain again once the surface has been opened.
Tools
- Lawnpecker: aerating with hollow tines, loosening with solid tines, spiking with the spike set.
- Levelling rake: spreading sand and evening out bumps.
- Drag mat: working in sand and seed.
