Mulch is usually replaced every year depending on the quality you select for your landscape. You can tell if your mulch is getting ready for replacement by simply looking to see if it is losing color or is getting thin. Standard mulch depth is roughly two inches. Check with your finger and see if you have lost depth.
So your mulch is ready for replacement?
When selecting mulch there are a few aspects to consider. Color, longevity, and shed quality.
Color: Mulch has a variety of standard colors: red (dyed), black (dyed), brown (dyed), and natural (not dyed).
Shred: When mulch is made from either tree bark, or wood from the interior of a tree it will be run through a shredder to make the final product smaller and more fine depending on how many times it was shredded. Mulch comes in roughly three different levels of shred quality with each consecutive level of shred you will be paying more. The finer your mulch is the better it will control weeds, decompose, and look.
- Single Shred: This mulch is usually hardwood, and will likely be the cheapest option. Chunks will be large and dye will hold for around one season.
- Double Shred: This is the best middle of the road option that balances cost, color, breakdown, and longevity. Generally you can get spring, summer, and fall out of this variant.
- Triple Shred: Triple shred is the most effective mulch in all qualifiers. While this mulch may be more expensive, it very well could save you money in the long run as it is so fine that it will break down to dirt in roughly a year. With triple shred you wont have to worry about removing last years washed out, moldy mulch to make way for this seasons mulch. This mulch will almost definitely last you year round and still be looking great.
Mulch Types:

Hardwood Mulch (Single Shred):
The mulch pictured here is brown hardwood freshly laid.

Hardwood (Double Shred) :
This brown mulch freshly laid.

Bark Mulch (Triple Shred):
This black bark mulch is freshly laid on top of single shred hardwood mulch.

Red Hardwood (Single Shred) :
This mulch is freshly laid at around three inches in depth.