1st Phase Redevelopment Complete!

The grove is beautiful this time of year with the trees exploding in dark green growth, walnut-size baby avocados peeping out here and there, the buzz of bees everywhere, and a blissful breeze flowing from the west. We recently visited the grove to check out the redevelopment, the first phase of which was completed in early May. As we pulled up the drive, we couldn’t contain the excitement at seeing the transformation from a dying and barren grove to perfect rows of hundreds of baby avocado trees. Our manager, Gary Dicks and his crew, did an amazing job. Here’s what went into it.

Planting Prep

The grove was prepped and cleaned of debris. Gary engineered the new layout on high-density 15′ X 15′ spacing plan. Each spot is flagged on the center. Using a small front-end loader, tiller and hand labor, crews tilled an approximate 4′ X 4′ area to mix native soil, compost and organic gypsum. They hauled a large mound of chip material (using the old wood chips from the avocado trees we removed in the fall), placing it next to each planting site to be used for top dressing mulch after planting. A total of 262 spots were prepped.

Irrigation Design and Installation

Prepping the new lines.

Prepping the new lines.

Our 5-acre grove is split into 5 main blocks, allowing water to be controlled differently in each block. A sub-line water main runs through the property with “block” ball valves to control the water flow to each block. Then there are secondary “hose-bib” ball valves to control the irrigation lines to the trees themselves. This gives us a good amount of control to vary the irrigation to meet the trees’ needs.

New valves and pressure gauges.

New valves and pressure gauges.

Crews dug new sub-main line trenches by hand. They installed a new 1 1/2″ SCH 40 PVC sub-main water line along with new 1 1/2″ block ball valves with pressure gauges and 3/4 ” hose bib valves with pressure regulators for lateral irrigation lines. A whopping 4500 feet of 1/2″ above ground poly hose lateral irrigation lines were laid. We had permanent, in-ground irrigation previously. I believe the above-ground irrigation is used because trees may be removed in the future to reduce the density as they grow. So this will allow the irrigation to me moved and changed easily. At each planting spot, they installed poly hose bases with 8″ risers and 20 gph half-circle micro jet sprinklers. All old block ball valves were replaced throughout the grove, not just in new planting areas. Each location of a block ball valve was staked and painted yellow while each hose bib valve was staked and painted red. The crews backfilled and compacted all trenches. They then pressure tested the entire irrigation system, cleaned sprinkler heads and checked for leaks.


Before planting the trees, the crews irrigated each mound with 200 gallons of water. We planted 260 certified Hass avocado and 2 Reed avocado trees on Clonal Dusa (Merensky 2) root stock purchased from Brokaw Nursery in Ventura, CA. This root stock was chosen for its resistance to root rot. Each tree was planted in a hole large enough for the pot and then soil was mounded up 1-2 feet at the base. After planting, they spread the reserved chip material over each mound. Each tree received 8 ounces of 11-7-14+18S+Zn+Fe and was irrigated again with 40 gallons of water.

Baby trees in their mounds with new irrigation lines.

Baby trees in their mounds with new irrigation lines.

Using backpack sprayers, the crews sprayed foliage and soil with 0-28-25, 0-60-0, growmore 20-20-20 and super thrive phsphorus acid nutrient mix. This will be the first of several applications this year for the baby trees. Each tree was also sprayed with white paint to keep them from getting sunburned.

So now all we can do is wait for approximately three years before we can get our first harvest!

Meanwhile, we still have two blocks in the grove with old trees to be redeveloped. We turned off the irrigation on one block because the trees in this area are dead and cannot be salvaged by stumping. The’ll be removed. The last block of trees will be stumped later in the summer or fall. Gary determined that 6 of the trees that we previously stumped last fall are unrecoverable because they have not sprouted new growth. He cut these trees to the ground and chipped the wood. Finally, 9 trees near the top of the pad (that had previously provided us glorious shade when we visited!) were also stumped to 7′ and painted with white latex paint to protect for sunburn.

So all in all, our grove is now a hodgepodge of 262 baby trees, 62 6-month old stumped trees, 9 newly stumped trees, approximately 100 dead trees to be removed, and another 97 or so 30+ year-old tall trees to be stumped! Plus, we have a few empty spaces from the 6 trees that did not survive stumping. We got a little of everything, but this way the redevelopment (i.e. costs) will be staggered.

The Great Water Debate

When we were first told how much water was needed to irrigate our avocado trees, I believe my response was something like, “BLEEP! What the BLEEP. BLEEP. Totally BLEEPing insane! Bleeeeeep.”

We believe the previous owner of our grove used approximately 300 gallons of water per tree weekly. Yes, that’s a 3 with 2 zeroes after it. Per Tree. Per Week. Rick Marrocco with Fallbrook Ag Labs recommended we leach our trees (more on this below) immediately with 600 gallons per tree and then regularly water each tree with 450 gallons every week, or when determined dry using a water meter or the clumping test. Our grove manager recommended about 400 gallons per tree, which is the regime we are currently following. Yes, our water bill is insane.

A healthy tree from our farm.

A healthy tree from our farm.

Given the variation in irrigation regimes implemented and recommended above, the question remains, what is the optimal watering regime for avocado trees? To be clear, it is very important not to overwater your avocado trees. You can’t water too much at once, but you can water too frequently. Using 300-600 gallons per tree may sound like we are drowning the poor things, but each tree has a calibrated spinner outputting 10 gallons per hour, so the trees are not flooded, rather, they get a slow seeping over 30 to 60 hours, depending on how much you want to water. Then they are allowed to dry out between waterings.


The great debate stems, in part, over leaching. The water in most of the districts in southern California, including the Rancho California Water District where we are located, has high levels of sodium chlorides and other salts. Salts are poisonous to most plants, but avocado trees are some of the most salt sensitive of all fruit trees. When avocados use water, they leave the salts behind which causes them to accumulate in the soil. To resolve the problem, some argue that the trees have to be watered a lot over a longer period of time to “push” the salts down past the root systems of the trees. This method is called leaching the salts. The excess water not used by the avocados transports the soluble salts past the root zone. Avocado trees have a shallow root system, but leaching the salts still requires very deep watering.

Reduced yield and leaf burn.

Reduced yield and leaf burn.

But does it have an impact on yield? The experts say, absolutely yes. The CAC states that high salinity leads to reduced water uptake in the roots, reduced nutrient absorption, compact soils causing problems with drainage and aeration, and a measured yield loss of 12% for every 35.5 ppm of chloride in the water (see here, or if you want to geek out on the science and math of it all, see here). The Ag Labs proved results with Rick Marrocco’s personal grove. The first year he took over management, yield was 2,700 pounds per acre. Two years later, that yield jumped to 16,000 pounds per acre. Leaching was one of the practices he religiously implemented.

Other Water-Wise Practices

This does not mean that we just turn the knob and let it run. The following practices should be implemented along with your irrigation regime to ensure water use is managed as wisely as possible.

  1. Use low-salinity water if possible. Sometimes you don’t have a choice though.
  2. Plant salt tolerant root stocks. Sometimes you don’t have a choice in this matter either if you inherited a mature grove, but if you eventually replant, that’s the time to seek out smart root stocks.
  3. Test your water and your soil for salinity. A method is provided here. You’ll want your EC (electrical conductivity) to be 2 or less. An EC between 2 and 4 restricts growth of salt sensitive plants, such as avocados.
  4. Make sure your spinners are in good order (outputting 10-12 gph) and use syninger 20 psi regulators. Regularly check your irrigation equipment.
  5. Allow trees to dry out between waterings.
  6. Use water irrometers, moisture meters, or the clumping test (i.e., if a clod taken 6 feet out from the spinner and down 3.5 to 4 feet sticks together, do not water).
  7. Apply gypsum to the soil.
  8. Turn off water on tree you plan to remove, or severely reduce watering for trees you plan to stump.
Example of leaf burn, distressed tree.

Example of leaf burn, distressed tree.

Damage from salts becomes obvious when you have burned leaf tips and leaves falling out of season. Our grove had obvious signs of damage early in the season when they were watered fewer gallons per tree. Soil tests conducted in three areas in May showed one severely high salinity area, another that was almost optimal, and the third area was good. And the records of previous yields did indicate room for improvement. So after I got all my cursing out of my system, the evidence seemed to suggest that these guys were right. We’ll see how our small grove fares under the changes we are implementing.