Weed control is very important to achieve those high sucess rates you are after.
Planting seedlings should be approached and carried out with the same vigour and diligence as you would if growing a crop like wheat, cotton, corn or lucerne. 
The whole idea is to conserve moisture and nutrients, in the soil, for the seedlings you are trying to grow. 

Methods of weed control can include cultivation, residual herbicide and mulching.

If the preparation work is done well, very little is needed after planting as the weed burden will take two growing seasons to get near the plants and by then your seedling will be far beyond weed impact.


Steps in weed control
- Start weed control 8-12 months before planting
- Slash, spray, rip, cultivate and maintain rip lines. Keeping weed free until planting.
- Mulch at planting and you may apply a residual either pre or post planting.
- If weeds are a problem after planting it is possible to apply a knockdown using plant shields or for grass you can use an overspray which will only kill grasses.