Mulching – What, Why, and How

11.7.16 – Mulching may seem intimidating, but it is not as difficult as it seems, and it can be very beneficial to the health and size of citrus trees. How much can adding a natural extra layer on top of the soil really do? This piece was written by Food Forward staff and Catherine Achy, one of our student interns from UCLA, and is part of our essential series on fruit tree care.

What is mulch?

Mulch is any type of organic material that is spread over soil as a cover. Some examples include bark, twigs, leaves, wood chips, grass clippings, pine needles, newspaper, cardboard, compost, and manure.

Mulch has many benefits for soil and plants. By covering the soil, it reduces the evaporation rate from the soil, locking in moisture and increasing the amount of water available to plants and soil biology (and cutting down your water bill!). This also keeps the soil temperatures cooler. In addition, it breaks down over time to provide nutrients for microorganisms in the soil which increases biodiversity. The drier and thicker the mulch, the longer it will take to break down into soil. Mulch will suppress the growth of weeds and can have add a nice aesthetic to a residential yard.

Especially important for us here in Southern California, citrus trees treated with green manure have been shown to be larger in tree and fruit size than those treated with animal manure.

How to Mulch?

Food Forward recommends that all tree owners mulch their trees in order to save water and increase the health of the trees. This could be as easy as leaving the leaves that fall from the tree. There are also sometimes local options for free mulch in your community including local tree trimming companies, holiday straw bales, and excess plant material from other parts of yours or your neighbors’ yards. Many garden care stores also sell a variety of mulch types for landscaping use. We recommend choosing a natural mulch rather than a synthetic mulch so the tree receives added benefits.

  • Add a 2 to 4 inch layer of mulch around the base of the tree. This prevents weeds from growing while still allowing water to reach the soil.
  • Keep the mulch 12 to 24 inches away from the tree trunk. Mulch, and the water it stores, can contribute to fungi growth.
  • Maintain your mulch layer year round.


What to use?

Natural and organic mulches decay over time, adding nutrients to the soil, making them a better alternative to their synthetic counterparts. Yard waste is an easy and cost-effective option. Using yard waste as mulch helps to solve the urban waste disposal issue. 20% of soil waste in landfills is yard waste, and using this to mulch instead of throwing it away helps to lessen this amount.

  • Grass trimmings
  • Fallen leaves
  • Pine needles
  • Compost
  • Wood chips from local trees

You can read more about mulching at Mulch, mulch, mulch! And after you mulch, be sure to check out our other resources for tree-lovers like you here:

Learn more about Fruit Tree Care

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20 thoughts on “Mulching – What, Why, and How”

  1. Bruce says:

    Thank you for the information on mulch. I struggle every year with lawn issues. I am looking forward to tackling the yard now, knowing what I know now. Thanks again..

  2. Terri says:

    I need a bit of help. I have a lovely mulberry that has been covered in gravel ( I inherited this with the house). What’s a good way to mulch this lovely specimen?

    Many thanks!

  3. joe says:

    Hi Terri,

    Thanks for your question! I’m not as familiar with gravel mulch or mulberry trees, but the gravel may have some benefits as well as drawbacks. You can read more here:

    Good luck!

  4. Joan says:

    Do you work the old mulch in the soil before adding new mulch?
    How deep should you work the soil?
    How can you tell Natural mulch from synthetic mulch?
    Ours comes from a Lawn Service in a truck – loose.

  5. joe says:

    Thanks for your question Joan!

    If you follow the practice of no tilling, then it’s best to just add the new mulch on top of the old mulch. This minimizes damage to the soil structure and soil organisms, and is less work for you. If you choose to work the mulch into the soil, it’s best to work it into the first few inches only. Then add the new mulch on top.

    Natural mulches include hay/straw, wood chips, leaves, dried lawn clippings, compost, cardboard, bark, etc. Synthetic mulches include plastic sheeting (clear, black, or colored), carpet remnants, and even gravel or stone.

  6. David Gray says:

    A great site and information. I have been covering my beds with a wood chip mulch here in France for over ten years now and it keeps the weeds down and eventually they rarely grown, which is important in a garden that is really a field I am trying to tame.

    I use all my tree and shurb pruning and never water anything even during the height of the summer season. Also, I have discovered a good use for grass cuttings as a mulch and weed suppressant under my perimeter fencing shurbs. It encourages worms to take the mulch down and enrich the soil and eventually you get very few weeds.

  7. joe says:

    Thanks David! Those are great suggestions, and I’m glad that you’ve found some easy and successful sources of mulch!

  8. krishna says:

    So can we put mulch next to the garden on grass to walk on?

  9. joe says:

    Absolutely! In the garden, next to the garden, we’re all about the benefits of mulch and its many applications here. Good luck!

  10. Ann Thompson says:

    will the bulbs i planted come up if covered with mulch?

  11. Dale says:

    For some reason I have it in my head that you have to rake up the mulch in the fall. Is that not true? It just stays and you put more on top the next year?

  12. joe says:

    Thanks for your question Dale. The benefit to leaving mulch is that it breaks down over time, adding organic matter and nutrients to your soil! So long as you are using organic mulch (as opposed to synthetic), we recommend applying new mulch on top of the old.

  13. Maximo Cruz says:

    how much would a yard that needs 25 bags of mulch cost in labor these days?

  14. joe says:

    Thanks for your question Maximo! Unfortunately we’re not experts on hiring landscaping/gardening services, or labor costs. I’d suggest that you contact a few local businesses and compare quotes. Best of luck!

  15. Judy Kornbluth says:

    after I have cardboard and mulch, how long will this take to treat the previous lawn?
    Do I have to water it?

  16. John says:

    We just planted some Livingstone Daisy Variegated Trailing plants (Ice Plant) and the landscaper put mulch around them. Since they are a ground cover should mulch be put around them?

  17. Mark Stiegler says:

    I have been told that pine tree chips and pine needles are not good as mulch because of the acid in the wood and needles. Is this true? Also, I have a lot of Popular cotton wood wood chips. I would like to use them as mulch around bushes in our yard. Is cotton wood good as a mulch? Any restrictions?

  18. joe says:

    Hi Mark! Thanks for your question. You can absolutely use pine needles as much. You’re right that pine needles may make your soil more acidic, but that is not necessarily bad. Some plants require more acidic soil, and some soils may benefit from a slightly acidic mulch. It really depends on the pH level of your soil and the pH needs of the plants that you’re growing. We’d suggest testing the pH and doing some research into what kind of soil your plants prefer. Good luck!

  19. Bj Brown says:

    How can I make mulch in a black bag? Can it be done weeds and dirt only?

  20. Mona Beene says:

    how do i use left over food scraps for mulch?

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