Mulch Under Citrus Trees: Pros and Cons

Also: can cover crops beneath fruit trees stave off the effects of a frost?

Mulch under Citrus Trees: Pros and Cons

I love mulch (so did Tony the Cat). That would be obvious to anyone who has ever talked gardening with me. Big piles, small piles, inches of mulch scattered everywhere. Love it!

The benefits of adding organic mulch (wood chips, shredded tree limbs, pine needles, compost, straw) to the top of your garden soil:

• retains moisture

• keeps soil temperature constant, reducing plant stress

• suppresses weeds

• gradually increases soil organic matter

• attracts beneficial organisms that improve soil fertility and porosity.

• Mulch encourages healthier plants, reducing the needs for pesticides and fertilizers.

• protects roots and plants from mechanical injury.

• On hillsides and around homes, it suppresses the spread of brush fires.

But a long-held recommendation from the University of California flies in the face of the "all mulch, all the time" rule regarding protecting citrus from the effects of freezing temperatures: "A cover crop or mulch can lower minimum temperature at night, posing an increased threat from freeze damage."

So, our advice has been over the years has been, "rake away mulch from beneath citrus before an expected frost or freeze".

Now, the California Landscape Contractors Association and others are offering the opposite advice regarding frost protection: "Mulching with a partially composted material is one the best ways to protect plant roots because it helps insulate the soil, reducing heat loss and minimizing temperature fluctuations. Protecting the roots is necessary in order for them to survive the cold."

So, who's right? The late Sacramento County Farm Advisor Chuck Ingels advised: keep on mulching!

Chuck Ingels at the Fair Oaks Horticulture Center, 2002

"The CLCA is right on," said Ingels. "In our mild climate, mulch doesn’t protect the tree from cold because the soil and roots really don’t ever freeze. Mulch protects the soil for other well known reasons. Regarding that UC study: years ago I thoroughly researched this and wrote about it in "Protecting Groundwater Quality in Citrus Production". In a large orchard, the best orchard floor conditions for reducing frost hazards is bare, firm and moist soil. The sun hits the soil and re-radiates the heat at night, warming the air. Tall cover crops are worst because not only do those plants not hold much heat, but tall cover crops raise the level of cold air (cold air sinks), increasing frost damage potential."

"Perhaps with just a few citrus trees there may be some benefit in this regard," Ingels concedes. "But any difference is generally very miniscule. What happens on the surrounding five acres (asphalt vs. buildings vs. bare ground) affects the air temperature around your tree. So, mulch away!"

Farmer Fred’s Ride for the Kids!

I'm fundraising on behalf of the 2025 Sac Century Challenge on Saturday, October 4 to raise money for the Sacramento Children's Home Crisis Nursery, and I could use your support. Here’s the link.

On that date, I’ll probably be riding (it arrived!) my new (and probably last) bike, the FRED OTL (a custom Haley titanium bike, NOT an e-bike). “OTL” - in bike race parlance - stands for “Outside Time Limit”…participants who were sent home for being “dead ass last”. I never said I was fast. But I do persevere to the end.

The journey of 100 miles throughout the Sacramento area is to help out the Sacramento Children’s Home Crisis Nursery. I’ve ridden 100 miles in one day plenty of times…when I was younger.

But at 74, and with a few health setbacks in 2025, I could use some moral support, and the Sacramento Children’s Home Crisis Nursery can use your pledge money.

Because of those health setbacks, I’m having to prepare harder for this event. This will be the slowest century I’ve ever done, probably close to 10 hours on the bike. The doctors have not given their OK (yet) for me to do this, but to paraphrase Willie Nelson, “There’s more old bicyclists than there are old doctors, so I guess we should have another ride!”

The Sacramento Children's Home Crisis Nursery is the only program of its kind in Sacramento County and directly prevents child abuse and neglect by supporting families with small children at times of crisis. The nursery allows parents to bring their children ages newborn to five for emergency hourly or overnight care during difficult times, with the goal of keeping families together and reducing the number of children entering foster care. To care for our community's most vulnerable children, we rely on support from community members like you. By donating, you empower us to provide a safe haven for children throughout the Sacramento area, offering respite to parents during times of crisis, and building a strong support system for the future. Your support helps provide a safe place to stay local kids in need.

Again, here’s the link to make a donation to the Sacramento Children’s Home Crisis Nursery.

Say "Hi!" if you see me pedaling like crazy out there on Saturday, October 4th!

After the Paywall:
A deeper dive into the pros and cons of mulching deciduous fruit orchards, citrus, and vineyards.