My new lawn is now going into the 4th week and has a lot of patches, should we re-seed? Add fertilizer? It currently gets 15-20mins of water 3 times a day.

• Newly sown lawns can be patchy to start with. There does appear to be a lot of rocks and debris in the photograph of the top soil that the lawn is growing in.
• While it looks very free draining it is likely lacking in organic matter which helps retain soil moisture in summer.
• Now that summer is here it is getting late in the season to over-sow the lawn so continue with what you are doing through summer with regular watering.
• Once the lawn gets to about 10cm tall or 8 weeks established start mowing by taking the tops off the grass, the lawn will start thickening up and look less patchy.
• Continue mowing on a high setting for three to four mows and then continu mowing on a high setting, only take one third of the grass height off.
• You will help thicken the grass by fertilising with Tui LawnForce New Lawns, it is the only fertiliser that is safe to use on newly established lawns, other lawn fertilisers can’t be used until the lawn is at least 16 weeks established.
• Regular watering, mowing and fertilising will help thicken the existing lawn.  
• Once the lawn is more established and can be walked on it would be a good idea to remove the larger rocks and remove the broadleaf weeds by hand.
• In autumn over-sow the lawn, do this well before the first frost. Alternatively, do it in spring.
• To over-sow mow the lawn on a low setting using the catcher. Lightly rake the lawn to break up the soil surface tension, remove any dead plant material and rocks.
• Add a layer of Tui LawnForce Lawn Preparation mix, don’t put it on too thickly – a layer 0.5mm thick is enough and spread evenly over the existing grass. If lawn preparation mix is applied too thickly it will kill the existing grass.
• Sow the seed, the best way to evenly spread seed is by using a Tui LawnForce Hand Spreader or Broadcast Spreader along with Tui LawnForce New Lawns at the same time.
• Sow and fertilise at the recommended rate, water well, twice a day depending upon the weather and temperatures.  
• In summary the process for over-sowing is to mow the lawn on a low setting using the catcher; Rake out debris and break up the soil surface tension; Add a thin layer of lawn preparation mix to give the lawn seed something to grow into; Over-sow with lawn seed; Water twice a day until well established.