It’s important to use the right kind of fertiliser when dealing with new lawns. Setting seedlings/turf up with the right amount of nutrients will help the new lawn establish well leading to fewer weeds and a greener, healthier lawn in the long run.
Use a fertiliser designed for the job
Most fertilisers are not suitable for use with newly seeded lawns, high nitrogen (N) fertilisers are included in this group. Nitrogen forces leaf growth, this sounds ideal when you are trying to establish a new lawn but if the seedlings have not had time to produce a sufficient root system the end result is a grass plant that can’t support itself and is far more likely to struggle in times of stress (e.g. drought, frost).
Fertilisers that are very high in potassium (K) are popular in the autumn as K helps to prepare lawns for the winter ahead. Some potassium is required for new lawns but levels as high as 20% may have a salt level that does more harm than good. High salt fertilisers will draw moisture out of the delicate seedlings and could scorch the roots of newly laid turf.
Seeding fertilisers are usually described as such, this is certainly the case with SmartLawn Seed Starter. They tend to have low nitrogen and potassium levels (often with some slow release) and a relatively high phosphorus (P) level. The phosphorus is important for the development of new plant tissue and helps with the development of strong roots and leaves.
If seeding a new lawn from scratch the ideal method is to apply a seeding fertiliser prior to seeding. Spread the product at the recommended application rate and work it into the top 2 inches of soil with a rake. Compress the soil a little using a roller or the ‘shuffle’ method. Then seed over the top as recommended by your seed supplier. Water regularly in the spring until fully established, do not allow the soil to dry out completely.
If overseeding a lawn, apply the fertiliser and rake it to break the soil surface a little. Apply your seed over the top and water as needed. A regular fertiliser for growth can be applied to the lawn 4-6 weeks later when the new seedlings are well established.
If turfing a new lawn you can simply prepare the soil as recommended by the turf suppliers, apply a seeding fertiliser as per recommended rate and then lay the turf straight on top. Watering the turf regularly until new growth can be seen is very important to get the roots to establish down into the new soil.
The fertiliser can also be applied over the turf and watered in though this may not encourage rooting downwards as effectively. The deeper the roots the better in the long term!
A note about mycorrhizal relationships
Mycorrhizal relationships between the roots of grass plants and beneficial soil fungi are important for lawn health and help you get the most out of your applied treatments. In order to avoid inhibiting the formation of this special relationship, it is important that you do not go above the recommended rate with seeding fertilisers.
Once the lawn is established it is a good idea to follow up with a fertiliser feed that will continue the healthy growth and thicken the lawn to prevent weeds from growing. Most of the SmartLawn range are suitable depending on the time of year, AutumnGreen 10-5-10 is an especially good choice due to its low nitrogen level and lack of iron sulphate (which can easily scorch young lawns).