Griselinia Littoralis: Griselinia Littoralis a good alternative hedging plant salt resistance makes them particularly suited to coastal regions and a good option for roadside planting. Officially hardy to approximately -10 any less will almost certainly result in some winter foliage damage, nothing to be overly concerned with and in all but the rarest cases will not be fatal, any damage can simply removed and will be replaced when the temperatures start to rise.
How quick do these grow?
Its not exact as all planting aspects can vary slightly, but on average you should expect somewhere in in the region of 30 to 40cm per year.
New Zealand privet what heights can i expect and how many plant per metre?
These are already well established plants so two per metre. Maximum height left untrimmed can be 6m plus.
Are they easily trimmed?
Yes like all hedges you can literally chop off at the required height.
When should they be triimmed?
Early spring after winter and early autumn before winter.