Drivers have been warned of delays when part of the A338 Bournemouth Spur Road is reduced to a single lane so work can begin to clear grass verges.
The restriction, which will be in place from 0600 GMT on Monday for two weeks, is being carried out ahead of a £26m six-month refurbishment of the route.
The northbound carriageway will be reduced to one lane for two miles (3km) before the Ashley Heath roundabout.
The same work will be carried out later on the southbound carriageway.
Ecologists carried out work to relocate a number of protected species of reptiles from the verges in November 2009.
Dorset County Council said that any remaining wildlife would be moved in the spring after preliminary work was completed.
The reconstruction of 6.5 miles (10.5 km) of road and drainage systems is due to start in the autumn.