Multiple factors influence how long it takes for grass seed to grow, the most important being temperature, moisture and type of grass seed used. This makes it impossible to give one simple answer. Some seeds will show growth after as little as four days, whereas others might not show any growth for months depending on weather conditions. In this article we will discuss these factors amongst others to provide you with an idea of how long it will take your particular seed to grow, and what you can do to aid quick, healthy progress.
The first and most crucial stage of seed growth is germination. During this process the plant grows from within the seed and transforms into a seedling, overcoming the first barrier and showing the first visible changes in the plant. This delicate process is sensitive to many environmental conditions that need to be taken into account to foster healthy progress. The first of these to mention is soil temperature, as grass seed will not germinate at all if the soil temperature is below 5°C 1. This means that there is little point putting down grass seed in the north of Scotland during the height of winter as the seeds will be completely inactive until temperatures rise. Germination rate then increases with temperature up to the optimal soil temperature of around 15°C.
An equally important factor is the moisture in the soil, as likewise grass seed will not germinate without moisture.2 Fortunately in this case you can work around dry weather conditions by watering the soil yourself. If you do lay the seed during dry conditions we recommend you lightly water the soil at least once a day, or even twice in hot conditions, to keep the soil consistently moist. At the same time it is important not to overwater the soil as this can wash the seeds away completely or cause them to rot. Although with light watering from sprinklers or a watering can this won’t be an issue.
Another key element which will determine the success of germination is the nutritional values of the soil. Although seeds contain their own supply of food to help fuel their initial growth, there are some nutrients, most importantly Nitrogen, Phosphorous and Potassium, that it has to source from the soil.3 Without a sufficient supply of these nutrients the success rate of germination will fall greatly. Whilst some soils naturally contain enough nutrients for grass seed, especially high quality soils, we recommend always adding pre turfing fertiliser before laying seed to ensure an adequate nutrient content.
One final key variable is the species of grass seed that you are using, as each germinate at different rates. The most commonly used grass seeds in the UK are hardwearing mixtures which are generally a combination of Perennial Ryegrass and Red Fescue. 4 These seeds can germinate in as little as 4 days, but more often than not will take closer to 10. However other species such as Kentucky Bluegrass can often take around a month to germinate. If you are unsure as to what kind of grass seed you have you can look at the packaging or failing that check with your supplier.
Ok, now that your grass seed has germinated, you might want to know how long it is going to take for the leaves to grow and the grass to thicken. Unfortunately, this again depends on all of the previously mentioned factors to give an exact answer, but as a general guideline under normal conditions the grass will grow at a rate of around 2-3cm per week after germinating.
This means that for most UK lawns you will start to notice the first growth of your seed after 2-3 weeks from seeding. And then you could expect the grass to thicken and properly establish itself in 1-2 months. It’s important to remember that although you can not force your new lawn to grow at the exact speed you want, you can guide it in the right direction and speed up the process by providing the grass with the optimal conditions outlined in the previous section.
You’ve done everything you reasonably can to provide your seed with conducive growing conditions, but it’s been a few weeks without showing any signs of growth and your wondering what you should do now. The first thing to do is consider the variables discussed earlier and make sure you are certain that the seed isn’t growing, and your not just being impatient with a slow germinating specie in the middle of winter. If after considering these factors you’re not sure if the growth is normal or not, we recommend you wait another week or two before taking any extra measures.
Once your certain that the seed isn’t growing, it’s time to investigate the problem. The first thing to consider is abnormal weather conditions. Has it been freezing cold at night, or has it been scorching for weeks? Has it not rained for a month, or has it been raining torrentially for weeks? In any of these cases it could simply be that the temperature/moisture has prevented the seed from germinating/growing, and there’s not much you can do except wait for the weather to stabilise.
A few other common but fixable problems include:
Grass seed needs adequate sunlight to grow, and so should be planted no deeper than ½ Inch. Any deeper and the seed will struggle to get enough light.5
This often happens on dry soil that receives lots of traffic which results in a compaction of the soil. This means there is not enough space in the soil for the air and water that the seed needs. The simplest way to fix this is to use a spike aerator to poke holes into the soil.
This is somewhat uncommon, but still happens from time to time, often when seed has been stored in hot or humid conditions, or when it has been in storage for a few years. In this case you would have to but new seed to put down on your lawn.
This covers all of the common causes for grass not growing, and checking each of these will usually result in a fixing of the lawn.
To finish off we will cover a common issue that can easily be fixed, and that is birds eating your grass seed before it has time to establish itself. There are many elaborate remedies out there to prevent this common problem that often make a mountain out of a mole hill. The truth is that for most gardens this can be solved very simply by doing two things.
First, you should put down more grass seed than the lawn itself needs, taking into account that some of the seeds will be found by the birds. As an example, you can use 50% more seed than is necessary and be quite confident that enough seed will survive to healthily populate your lawn. Secondly, after putting the seed down, you should tread the seed into the soil to bury it slightly, thus hiding it from the birds. If too much seed is still visible you can even throw a thin layer of topsoil over the seed, keeping in mind not to bury the seed so much that it doesn’t receive enough sunlight.
In extreme cases with many birds constantly pecking at your garden, a few other measures might be necessary. A few of the simplest and most effective methods include using some kind of scarecrow, or a fake bird of prey to scare away the birds. Another is to set up bird feeders in your garden, as the birds will not go through the effort of digging through the soil if a much easier food source is available. And one final, natural remedy we recommend would be to place straw over the top of the soil, as this will act as a barrier to the birds and prevent them getting to the seeds without covering too much sunlight.
To conclude, there are a multitude of different factors which you need to take into account when determining how long your lawn is going to take to grow. But ultimately you should aim to provide it with the best conditions, and not panic if it doesn’t immediately show signs of growth. There is a certain art to growing a healthy lawn, but it’s by no means rocket science. By carefully following the measures outlined in this article you’ll have a full and healthy lawn growing in no time.
Will Grass Seed Germinate on top of Soil?
Yes! However germination success will increase greatly if you rake the soil and lightly tread the seed in.
Does Grass Seed go Off?
Yes, eventually. After around two years in storage grass seed will show a noticeable reduction in germination success, and this will increase as more time passes. Also seed stored in poor conditions, i.e in high humidity or temperature will go off much faster.
How do I know if Grass Seed is Germinating?
To check if grass is germinating look for sprouts emerging from the seeds and green colouration. Both of these factors indicate that germination is taking place.