The secret to a healthy garden starts at ground level.
For as long as trees and plants have existed on earth, their leaves have fallen to the ground, forming a natural protective layer over the soil. This protective layer provides ongoing nutrients to the trees and plants, keeps the soil moist, as well as protecting their root systems from the heat of summer and the harsh frosts of winter. The plants in your garden need the same protection to keep them healthy.
The difference between Compost and Mulch ! 
Compost is always thoroughly decomposed. The main purpose of gardening with compost is to release nutrients into the soil as rapidly as possible.
Although many mulches decompose and become compost over time, the function of mulch is to act as a weed suppressor, and provide a barrier to protect your soil from heat, cold and frosts, as well as wind. The layer of mulch is exposed to all of the elements. Because compost is already decomposed and full of nutrients it makes sense to use it directly into the soil where it”s most needed. Left exposed to the elements it would very quickly lose all of the valuable nutrients your soil needs
Experienced gardeners already know the many benefits of mulching the garden.
A good mulch will;
1) Prevent the surface of the soil from drying and reduce the amount of watering required.
2) Reduce weed growth. Weeds compete with your plants for nutrients and water.
3) Add nutrients to the soil as well as improving the texture and friability as the mulch breaks down.
4) Reduce erosion, especially on banks and slopes.
5) Keep plant roots cool during summer, and help stabilize soil temperatures.
6) Protect plant roots from the damage of frost
7) If used around the base of trees and shrubs allow you to mow up to the edge of the mulch, and eliminate the damage caused to tree trunks by lawn mowers and clipping equipment.
Make your garden look more attractive and add to property value.
Organic mulches will decompose over time. As the mulch decomposes it will enrich and improve the soil, increase aeration of clay soils, and add water-holding capacity to sandy loam.
Organic mulches also contain mineral elements essential for plant growth. The hours you spend gardening will be well rewarded when you take a little extra time and finish with a layer of organic mulch.
The recommended mulching depth is 21/2- 3inches (75mm).
Mulch applied too thick can reduce drying and lead to water-logged soil, particularly during wet seasons or in heavy clay soils. Extended periods of wet soil especially in spring can be damaging to a number of perennials, azalea, rhododendron, and conifers, as well as making any effective gardening difficult.
Excess mulch, applied against the stems or trunks of trees and shrubs, leads to constantly wet bark which can cause rotting or disease.
Even when applied at the correct depth, it’s always better to keep the mulch a few inches away from the stems of your plants, especially those with woody stems or trunks, to avoid the problem of wet bark .
Another problem with overly thick mulch is that it can become a warm haven for insects and rodents to live and breed. 
There are many different types of mulch and choosing the best one to suit your particular gardening need will be determined by where you live in the world, and what you want your mulch to achieve for you. Your local Nursery can advise you of the best mulches to use in your area.
