What Homeowners Should Know Before Ordering
When planning a mulch or decorative-rock project, one of the first questions is often:
How many cubic yards do I need?
But another question has to come first:
How deep does the material actually need to be?
Depth affects how the finished landscape looks and performs. It also directly affects how much material you need to order.
Before calculating quantity, determine the appropriate finished depth for the project. And if the area already contains mulch or rock, don't calculate as though you're starting with an empty bed.
New Installation or Existing Installation?
The first step is deciding which type of project you have.
For a new installation, ask:
What depth does this material need for this project?
For an existing installation, the question changes:
How much material is already there, and how much needs to be added to reach the appropriate finished condition?
If an existing bed still contains usable material, ordering as though the bed were empty can result in more material than the project needs.
How Deep Should Mulch Be?
For an ordinary new landscape mulch installation in Florida, 2 to 3 inches of finished depth is a good general range.
That is enough for mulch to perform many of the jobs homeowners expect from it, including helping conserve soil moisture and suppress weeds. Too little may not provide the expected coverage or benefits, while an excessively deep layer can interfere with water and air movement.
Mulch should also not be piled against tree trunks or plant stems.
The key is total finished depth. The 2-to-3-inch range does not mean adding another 2 to 3 inches to mulch already in the bed.
Before Adding More Mulch, Check What's Already There
Mulch changes over time. It can decompose, settle, move and gradually become incorporated into the landscape. Different mulch materials can also change at different rates.
That means there is no reliable rule that every mulch bed needs the same amount added each year.
Suppose you want a finished depth of 3 inches and the bed still has about 2 inches of usable mulch. You would not automatically add another 3 inches. The existing material counts toward the finished depth.
In some areas, existing mulch may simply need to be loosened or redistributed. Other areas may need additional material.
Check what remains before deciding how much more to order.
How Deep Should Decorative Rock Be?
Decorative rock requires a different approach because there is no single depth that is correct for every decorative-rock project.
The appropriate depth depends on the purpose of the installation, the characteristics of the stone, the conditions underneath it and what the finished area is expected to accomplish. Stone size and shape can also affect how well the material covers the surface.
For those reasons, a chart assigning one required depth to each stone size would be misleading.
There is also an important Florida distinction. Decorative rock can be used in many landscape applications, but it should not automatically be treated as horticulturally interchangeable with organic mulch around plants.
For decorative rock, the appropriate depth depends on the needs of the particular installation rather than a universal number.
Before Adding More Rock, Look at the Existing Bed
Decorative stone generally does not decompose like organic mulch.
If an existing rock bed looks thin, inspect it before ordering more. Stone may have moved, settled into the underlying surface or become mixed with soil and debris. Some areas may be exposed while plenty of stone remains elsewhere.
Additional rock may be needed, but don't automatically order another full installation layer. Determine what the existing bed actually needs to reach the desired finished condition.
Make Sure the Finished Depth Fits the Space
The desired depth also has to fit the available space.
Look at existing material, edging, nearby sidewalks and driveways, surrounding lawn and the existing grade.
If a bed is already near the top of its edging or adjacent pavement, adding several more inches will change the finished elevation and may cause material to spill onto surrounding areas.
Consider that available space before deciding how much additional material the bed can accept.
Depth Changes How Much Material You Need
Once you know the appropriate depth, you can determine how much material the project requires.
For the same area, increasing the depth increases the volume in direct proportion.
For example, if an area requires 2 cubic yards at 2 inches deep, that same area would require 3 cubic yards at 3 inches deep.
That's 50 percent more material simply because the planned depth increased by one inch.
When you're ready to calculate your project, the cubic-yard calculators on applicable Mulch & Stuff product pages let you enter your project measurements and select the planned depth to estimate how much material you need.
This is why depth needs to be decided before calculating cubic yards.
Decide the Depth Before You Order
For a new installation, determine the appropriate finished depth.
For an existing installation, determine what is already there and what needs to be added.
Then calculate the quantity.
Depth first. Quantity follows.
