To do this you of course need materials and seeds.
1 Dunegrass seeds
2 Sunburst seeds
3 Root beard mushrooms (if you want faster growth)
4 Acorns
5 sandstone
6 copper

The early stages of this will be repetitive and take a lot of watering but the end will be worth it.
1 Scattered across the dunes are springs that have Thorntails around them when you find one plant
Dunegrass and Sunburst seeds around it then wait for the Sunburst to grow, when it grows, turn it
into a meadow mother rinse and repeat.
2 After all springs have Sunbursts around them start building sun sigils in the gaps between them
then plant Dunegrass and Sunbursts.
3 As the progress you may find lots of vigils that can make your plants grow better you should find all
the wind worn and sun vigils.
4 Once you have lots of meadow plants patches of random meadow plants that are found in the
dunes (no witchwood and ancient dunegrass or anything like that).
5 With many plants come many seeds that can be used for food or restoring other areas.

(plant guide, salt flat greening guide, etc)