lawn

have laid new lawn from turf it was 30cm at first now about 70cm started to seed here and there how long before i cut it also my tomato plants have brown spots on bottom leaves just starting to flower

 

I hope you mean mm not cm

If it's 70mm high now, you can give it the first cut, but before you do it's worth checking that it has rooted properly - just try gently lifting a corner of one of the turfs - if it resists, it's rooted OK.

You'll want to give it the first cut with a rotary mower ideally, and don't remove more than 1/3 of the overall leaf height in one cut - so in your case, not more than 20-25mm.

Keep cutting it at that height for a few cuts, and gradually start to reduce the mowing height to where you want it to be.

Don't know about the tomatos though

 

thank you WILL only have hover mower but can change height will give it a bash tomorrow evening thank you once again