Fertilising the lawn: when is the right time?
When it comes to lawn fertilisation, the timing is crucial. This is our guide to when and how often the lawn should be fertilised.
Every year in spring or autumn, many lawn owners suddenly realise that their lawn probably needs to be fertilised. And they are correct: a lawn must be supported by fertilisation in order to retain its health, vibrancy and density. Most lawn owners are aware that their lawn probably needs to be fertilised to stay healthy, vividly green and dense. But the question is, when is the right time to fertilise the lawn?
When is the right time to fertilise the lawn?
Not only the choice of the right fertiliser, but also the timing is decisive in lawn care. Using nitrogen fertilisation at the wrong time can promote frost damage or fungal diseases. If the lawn is fertilised too late in autumn, the vital potassium is not absorbed correctly and the grasses are not strengthened against frost. Below we explain when and how often a lawn should be fertilised to keep it healthy.
When and how often per year should the lawn be fertilised?
This depends on the type of soil and fertiliser used. In general, a lawn should be fertilised two to three times a year. The first fertilisation in spring stimulates the shoots, the second fertilisation in early summer prepares the lawn for the strains of summer and the third fertilisation in autumn brings the lawn plants safely through the cold season. Organic fertilisation is always carried out one month earlier than mineral or organic-mineral fertilisation.
Note: The earliest fertilisation in spring is not necessary on heavy soils on which the grasses do not require any initial help to bud.
Fertilising the lawn in spring
On heavy, clay soils, the first fertilisation takes place in May or June and only two doses per year are applied. Organic fertilisers should be applied in April or May. On light, sandy soils, the first fertilisation is carried out in March or April, provided that the weather is favourable. Organic fertilisers are applied in February or March. At this time, it is also possible to fertilise more thoroughly and use a larger amount of organic fertiliser. In this way, you can fertilise only twice a year, as opposed to three times.
Medium-heavy, loamy-sandy or loess soils can be fertilised for the first time from May to June using an organic fertiliser. In this way, one can avoid damage to the lawn, soil or environment even if the fertilising is not perfect. By observing sprouting in spring and decline in growth in autumn, you can adjust the fertilisation the following year. It is best to fertilise one month before the lawn requires nutrients with an organic lawn fertiliser.
If you need more detailed information about the spring care of your lawn, we recommend this article for lawn fertilisation in spring or this article, which also deals with the first mowing, scarifying and fertilisation in spring.
Summary: fertilising the lawn in spring
- On light soils, fertilisation is carried out for the first time in March/April, on heavy soils in May/June. Organic fertilisation always takes place one month earlier.
- On medium-heavy soils we strongly recommend the use of organic fertilisers or very precise observation of sprouting and growth – otherwise, lawn damage or leaching might occur.
- It is important to fertilise organically early and in sufficient quantity to ensure supply throughout the summer.
Fertilising the lawn in autumn
The last lawn fertilisation of the year generally takes place between June and October. If you want to use a mineral or organic mineral slow-release fertiliser for autumn lawn fertilisation, make sure that the fertilisation process ends before October at the latest to prevent leaching into the groundwater and frost damage to the lawn.
Fertilising lawn in autumn is best done with an organic fertiliser. If the rest of this product remains in the soil over the winter, it stops releasing any further due to the cold temperatures and can only be used again when it is warmed up in spring. However, do not apply an organic fertiliser too late in the season so that the lawn has enough time to absorb the important potassium. This increases cell walls’ stability and frost resistance.
Summary: fertilising the lawn in autumn
- The last lawn fertilisation takes place between June and October.
- Organic slow-release fertilisers are the only ones you can actually apply until October. Mineral fertilisers can cause lawn damage if applied too late.