A bark mulch will act as a natural barrier to insulate the roots of your plant against drought and extreme heat and cold.
It also has the added benefit of restricting weed growth.
The best time to apply a mulch is late winter and early spring, when the rain has completely soaked the soil.
If you need to apply a mulch at any other time, then soak the area first, preferably with rain water.
Dig out any weeds from the area, making sure the roots are removed whole. This is important as any small pieces of weeds will grow again and push up through the mulch.
Alternatively you could apply Resolva 24H Weedkiller which will do the tough work for you. This weedkiller goes right down to the weed root and starts to work within just 24 hours.
Spread a layer of mulch, such as Westland Bed & Border Chipped Bark around the plants in your border, to a depth 5cm (2 inches), taking care not to allow it to touch the stems of young plants initially.
Mulch around clumps of plants and shrubs until you have created a uniform surface over the whole area.
Any dust will be washed off when it rains.