The difference between seeding and overseeding is that the former relates to starting a lawn from scratch whereas the latter is for repairing damage or sparce / bare patches in an already established lawn. It is important to first establish why your existing lawn may be failing and treat the cause of the problem (for example a leatherjacket infestation) before heading out to buy grass seed. If the cause of the problem is still there and has not been treated, then any new turf or seed will also likely fail.
When choosing grass seed it is important to take a few things into consideration such as geographics including water level, sun/shade ratio as well as the level of use the area will have (i.e. a heavily used traffic area) which are all factors for choosing the right seed for your needs. Temperature is also vital as for successful germination the daily temperatures need to be above 13oc with a soil temperature of 7oc or above that is not too wet or dry. These conditions loan themselves to spring and autumn with germination taking between 7-21days in the right conditions.
Seeding a New Lawn
As with most things in life, preparation is key! For best results soil should be free from weeds, moss or any debris such as large rocks/stones, should be free draining and as level/even as you can get it. This can be achieved by digging over the soil to a depth of 20-25cm removing debris and weeds by hand or by using a weedkiller if there are numerous weeds present to make it easier. If the soil is of poor quality, topsoil can be added before levelling off.
Sow your chosen seed as per the recommended rate stated on the packaging either by hand or with the aid of a spreader such as the Turfmaster Push Broadcast Spreader. Lightly rake in the seed and firm down with a roller or by foot if the area is small to improve contact with the soil and thus increase the success of germination.
Overseeding is different to reseeding as you will be adding to an already established lawn rather than starting a lawn from scratch. There are many reasons for overseeding such as to infill damaged patches caused by environmental factors (such as being a high traffic area or pets) or as part of a routine maintenance programme to improve the overall colour and health of your lawn whilst reducing weed and moss invasion.
As with seeding, preparation is the key to success. For the best results it is important that the seed makes contact with the soil and that it hasn’t been obstructed by thatch or long grass to enable it to germinate. Therefore, before sowing any seed, the area should be mown short to approximately 2.5cm in length and then a spring tine rake should be used to break up and remove any thatch. If you have a large area or a particularly dense area of thatch it may be beneficial to use a scarifier.
Applying a pre-feed treatment such as Stripy Green Fertiliser at a rate of 35g/m2 seven days before sowing grass seed is recommended but for ease of use, Stripy Green can be applied at the time of sowing seed which can be more practical.
After the area has been cleared, spike the lawn to a depth of approximately 15 cm using a garden fork or an aerator at 30cm intervals. Sow the grass seed at the recommended rate detailed on the bag and gently firm down by foot or roller. To protect the seeds from being eaten by birds, the area can be covered with taught netting or garden fleece. However, these should be removed once new shoots start to come through the soil. If possible, keep traffic over the newly overseeded lawn to a minimum for 7 to 21 days to allow it time to establish and raise the mowing height to approximately 50mm for the first few cuts, then reduce to 25mm for the following few cuts. A general rule is to never remove more than the top third of the grass blade or the top quarter if the grass is newly sown.