Rock vs Mulch Landscaping

Are rocks or mulch better for landscaping? Is one better than the other for flower beds or around trees? The creative use of rock or mulch provides a fresh, finishing touch to any landscape. They conserve water, prevent weed growth, and slow erosion. Both elements have pros and cons depending on the type of landscaping situation.

Differences Between Mulch & Rock in Landscaping

Organic Mulch

Landscaping mulch typically comes from shredded bark, straw or compost, and is available in multiple sizes, from large nuggets to finely shredded. These natural elements deposit rich nutrients into the soil that help nearby plants thrive and grow faster.


  • 2x Growth Rate: mulch can double the rate at which trees and plants grow, according to a study done by Kansas State University
  • Fewer Weeds: mulch stops weeds from sprouting in your flower beds
  • Less Water: plants require less water to survive since mulch prevents water evaporation
  • Affordable: organic mulch is often much cheaper than landscaping rocks as a short-term solution
  • Reduces Erosion: mulch can reduce soil erosion and compaction by up to 85%


  • Periodic Replacement: weather and time will require you to replace organic mulch once every 1-4 years, depending on the mulch type
  • Timing is Important: if you mulch too early or too late in the season you could increase the risk of late-blooming or weed growth

How much does mulch cost?

The cost for mulch installation depends on the type and quantity of mulch used, however on average prices can range from $30 – $45 per yard, or $3 – $5 per bag.

Professional mulch installation is likely to range from $160 – $270 depending on the size of the yard and landscape design. Landscapers often charge by the hour or square foot.

How much mulch do I need?

A healthy mulch layer is typically 2-4 inches deep, depending on the mulch type. One cubic yard of mulch typically covers 324 square feet of ground an inch deep. Most mulch types are sold in 2 or 3 cubic foot bags.

To determine your total amount needed, use this simple guide:

  • For finer mulch, aim for a 1-2-inch layer. Multiply your square footage by 2, then divide by 324 = the number of cubic yards needed. Multiply the number of cubic yards needed by the size bag to determine the total number of bags needed.
  • Shoot for a 3-4-inch layer for coarser mulch. Multiply your square footage by 4, then divide by 324 and follow the same steps as above.

Landscaping Rocks

Stones and rocks are an ideal hardscape material that can be used to highlight the beauty of your plants and flower beds. The wide variety of choices available in O’Fallon and St. Charles guarantees a unique finish. Rock mulch does present some challenges that organic mulch does not.


  • Low Maintenance: landscaping rocks never need to be replaced, unlike mulch
  • Lower Long-Term Cost: stones are generally less expensive compared to mulch that must be replaced at least once a year
  • Weed Control: rocks can suffocate weed growth better than organic mulch


  • Hot Temps: some rock types hold heat much longer than others, which can raise soil temperature that in turn puts stress on thirsty plants
  • Impede Pruning: landscaping rocks prevent landscaped from thoroughly pruning shrubs and bushes
  • Creative Constraints: it is much easier (and cheaper) to rearrange or change an organic mulch landscape than landscaping rock

Or, give Greenside Lawn Care a call at 314-479-4005 for a free landscaping quote and let us do the math for you. 

Learn more about our other landscaping services in St. Charles, MO.