Sowing a lawn organically seems to have 2 problems that need solving:
- Killing the weeds prior to sowing
- Avoiding weed growth after sowing
Once the soil is levelled, I'm considering trying the false seed bed technique to kill off any remaining weeds before sowing grass. Wikipedia's article on false seed beds suggests hoeing the soil after 2 weeks, and probably repeating that step again at least once to be sure. If the technique is repeated enough, perhaps weed growth after sowing can be mostly avoided?
Has anyone had experience sowing a lawn with the false seed bed technique? Is there any other advice that might be useful?
I have recently built a house and the earthworks have resulted in approx 180sqm of a bumpy and difficult mixture of soil and pebbles around the house that I'd like to be lawn.
I know there are heaps of weed seeds in the soil as lots have sprouted over the last few weeks. Our first step will be to have the land levelled with a small digger as there's too much soil to shift by hand - this will hopefully kill off most of the weeds currently growing on the surface, but I'm sure it will also expose more weed seeds.
I have obtained quotes from tradesman for sowing the lawn, but they want to spray with a broadleaf herbicide several weeks after sowing to kill off weeds. Researching the ingredients in the proposed spray (picloram being one), they appear to be very safe in the short term but very little appears to be known about long term effects. It is also toxic to aquatic life, will readily drain through soil into the groundwater (our region uses mostly groundwater for irrigation and drinking!), is long lived, and may affect plant growth when it ends up in our compost. Interestingly, picloram also appears to be considered inappropriate for residential use. Going organic seems like a sensible option!
Update: I hoped the grass would win competing against other plants. After having some issues with birds eating the seed on the day it was sown, I resowed some areas then sprinkled sieved soil over the whole area to protect the seed. It took about 3 hours to sieve enough soil.
Now, something like 10 months later I think, the grass is growing well, however clover is healthily coexisting with the grass. In a few parts which didn't get enough grass seed, the weeds, such as plantain and ox tongue, are much more prolific, so it's clear the grass is dominant enough to keep them down where well sown. I've dug out a few thistle and ox tongues that established themselves amongst the grass.
I'm allergic to beestings, so my daughter might be too, which is why we'd rather not have much clover around; it attracts lots of bees in summer. One suggestion I've had was to add nitrogen fertiliser to make the clover bolt and then die off. I'm not sure whether any organic fertilisers would be adequate for this, or whether I'd need to use a non-organic one such as superphosphate.