Project sets cost of California Native Grassland Restoration at $225,000 per acre!

Photos and text by Craig Dremann, The Reveg Edge, Box 361,
Redwood City, CA 94064 - (650) 325-7333


The history of the UC Davis/Caltrans grant project shown on this website, starting on Feb. 11, 2003, in Yolo County at the I-505, Road 14 exit test plot site in the Sacramento Valley, California:

landscape planting Dunnigan Hills
(Just across the Interstate, there's a second native plant test plot, planted by the Yolo County RCD, see below).

First attempt, a couple of acres drill-seeded with several species of native grasses, seedlings are 2 inches tall, Feb. 11, 2003.
Dunnigan Hills test plot
Above: First attempt of Dunnigan Hills Caltrans test plot, looking south, February 11, 2003.
Above: The Yolo County RCD test plot, Dunnigan Hills, across I-505 from the Caltrans plot, March, 2003.
Some of the hummocks in background are the exotic perennial grasses. Checking the area in September 2004, there was a stand of about 50% cover of the native perennial grass Stipa (Purple Needlegrass).

First failure, Dunnigan Hills UC Davis/Caltrans site, June 2003. This first-year's planting was declared a failure and the site was sprayed in May and a second attempt planned for autumn 2003
...What is all that brown stuff?

rye gras
Lodged polyploid ryegrass, six inches deep!
This is one of the aggressive pasture-types developed in Oregon, now showing up here in California as weeds.

Above: October, 2003, with the Dunnigan Hills site burned and ready to reseed to try again.

SECOND TRY: January 18, 2004: Photos below show the Dunnigan Hills test plot second attempt underway.
landscaping Stipa
January 2004, part of the site had been recently mulched with a light covering of native needlegrass straw (Stipa or Stipa). The exotic grasses have been managed over the whole two acres, but what is left is a lot of bare soil that's eroding, plus seedlings of broadleaf weeds: mostly filaree, mustard, dock, milk thistle, and vetch. Yellow star thistle seedling not observed yet, but they don't usually show until later in spring.

star thistle
Second failure...Oh, no!...May 2004, the upper portion not solid yellow star thistle!

native grasses
However, in May, 2004, the Dunnigan Hills site did have about 1,000 plants of various native grasses.

AUGUST, 20, 2004. The upper portions of the Dunnigan site formerly covered with yellow starthistle was mowed earlier in the summer. Wild oats encroaching, plus some very robust "Blando" brome into the former native grass test plot area.

The test plots of various species of California native grasses are still standing in August 2004, but may not survive though the winter of 2004/2005.

September 9, 2005: A total of only four native grass plants appears to have survived in the whole Dunnigan Hills test plot site, and the area was recently mowed.

Former upper test plot area.

Test plot area, arrow is where the line of wooden stakes is located.

Third replanting attempt, July 12, 2006 - Another replanting attempt, unfortunately failing:
Between September 2005 and spring 2006, the test plot was plowed and resown by drill-seeding
with Elymus glaucus and some four-inch tall Purple Needlegrass, that is barely surviving as an understory beneath the weeds. This test plot has been treated like an annual flower-bed, resown every year and hoping for the best. No ecological restoration technologies have been used or successful techniques invented on-site, that would guarantee plant survival and establishment.

Plants seen in the photo are exotics, with the 4% native grass cover underneath the weed canopy. By September 2006, this whole area was mowed to about 3 inches tall, and you could clearly see about 1% Purple Needlegrass cover still surviving. That means for 2 acres, only about 1,000 sq. feet total of native grass cover survived.

Fourth planting attempt, spring 2006, UC Davis took over the Yolo County RCD test plot area, and it was plowed and replanted, by drill seeding on 8 inch-centers,
mostly Purple Needlegrass and some Elymus glaucus, which has formed a nearly solid stand by July 2006. Each plant is growing on 4-8" centers within the drill-row. However, in the distance you can see scattered wild lettuce and mustard plants, and even at these very low amounts, could eventually start the domino-like collapse of this nice planting.

Along the mowed roadside edge of this planting at this time, is a solid 80% yellow star thistle, 10% mustard, 5% ryegrass and 5% wild lettuce cover, just waiting to invade. Planting only two species of grasses does not necessarily recreate a self-sustaining California grassland ecosystem . Scattered within the planting are these same weeds, plus a understory carpet of the vine, bindweed.

August, 2007, planting is still intact.

Notice the wide spaces, without other species of native plants between the native bunchgrass plants.
"Vacancies" in the planting can allowing weeds to colonize. Islands of weeds, once they get established, like patches of mustard, can unravel the planting from within. Or star thistle can move into the bare spaces, like a wave, from the edge.

August, 2008...Oh, no, what's all that spiny stuff invading the native grassland? Mostly yellow star thistle coming in from the edges! The green in the center, is the wild lettuce starting the destruction of the planting from within. About 10% of the planting is already solidly infested, and will probably last another ten years under drought conditions, or 2-4 years with normal rainfall.


Update, August 2009:

Wild oats still invading from the left, and the star thistle and mustards from the right.

Solid star thistle, and star thistle plus mustard

star thistleStipa
Star Thistle (left) plus Stipa native grass (right) in the east side test plot, when unmolested by the weeds. All of the Elymus glaucus plants have died.

FIFTH PLANTING ATTEMPT. The west side plot was resurrected by a professor at UC Davis, and replanted in autumn 2008 with a drill seeder. Then, the plot mowed in late 2009 and late spring 2010. Only 15 pounds per acre of Stipa cernua, which produced only about 30% coverage. Photos August 23, 2009

landscaping landscaping

Notice the big gap between plants, with nothing native in between to fill in the spaces. The big gaps are equal to putting out a huge vacancy sign, with lots of room for weeds to move into.

Update August 2010
star thistle
What a typical I-5 or I-505 interchange, how it looks in August, solid yellow star thistle
star thistle
Dunnigan Hills test plot site, NW corner where nothing has been planted yet, solid yellow star thistle.

East side site, mustards moving in from the west.
Mustards moving in on east side plot.
The unmolested Stipa grasslands.

The edge of the mustards, eating the Stipas for lunch, like a giant amoeba.

West side plot, with about 30% Stipa cover, mowed in early spring.

Stipa cover on west side plot.
Mowed Stipa, too close, regrowing.

What was done in the fifth resowing in the west side plot,
which may cause future failure:

(1.) The plot was drill seeded on 8-inch centers instead of broadcast-sown.

(2.) The sowing rate of the Stipa grass was drilled at only 15 pounds to the acre, or only about 1/5th of the rate per acre needed to get good cover on the site, and,

(3.) Only one native species of grass survived, and no other natives were sown to fill the niche of the broadleaf weeds, like anything from the sunflower family to take the place of the yellow star thistle, for example. No legume family, no Indian paintbrush family, no milkweed family, etc.

Update August 2011 - Are we ever going to see solid native cover on these test plots?

East side plot baled, probably to manage the weeds. Star thistle plants mixed in the bales--what you can do with these bales except compost them? A 100-pace toe-point transect only produced 26% native grass cover, 3% mustard and the rest were annual weeds.

star thistle
West side looking OK, with yellow star thistle moving in from the north, and measuring a 100-pace toe-point transect, 46% Stipa cover, 2% Elymus glaucus, 32% annual grasses, 15% wild oats, and 5% yellow star thistle.

Old plants of Stipa on the west side, 5-8 inches in diameter

yellow star thistle
Oh, no...what is that infestation of yellow star thistle, coming in from the north?


The west and east side project have both stabilized at exactly the same amount of native plant cover, all Stipa pulchra, at 28%, with 72% weed cover.

UPDATE May 2012

West side plot

East side plot, mustards coming in thick, as predicted.

Little or no rainfall in January and February, has severely knocked back the annual grass weed seedlings, so the perennial native Stipa has been given an advantage and in the West plot has increased to 38% cover, and also 2% of native lupine is now showing up, probably from dormant seeds that were in the soil underneath the weeds. The remaining 60% weed cover on the West side is a 20% cover of wild oats, 8% red brome, 6% Blando brome, and 2% cover each of yellow star thistle, and bindweed.

The 38%-46% perennial native grass cover is probably the maximum cover for the grasses, and now the remaining 60% that is weeds, needs to be converted to the other native grassland plant families, like the sunflower family, and the poppy family, etc.

If we look at this project and calculate how much it cost for every percentage of native cover, that means that it cost about $6,447 for every one percentage of native cover that was produced. Therefore, to get 100% cover at that rate, would ultimately cost $650,000 per acre.

Update July 2013

star thistle
West side plot getting star thistle infested again. The West side was mowed to about two inches tall, and was 34% weeds, 62% Stipa and 4% yellow star thistle. The East side plot was not mowed, and was 72% weeds and 28% Stipa. Medua head grass and tumbleweeds present in East side plot.

Updated August 26, 2014

EAST SIDE: Finally Stipa is now 85% cover, mostly due to the exceptional drought knocking back the weeds, and the weed grasses are now down to 15%, mostly wild oats, medusahead and weedy Bromes. This side not mowed.

WEST SIDE: Mowed to 3 inches tall, Stipa 36% cover, weed grasses 64% cover. Mowing during the drought seems to knock back the native grasses, rather than help them, and the Stipa cover has shifted significantly downward.

Update August 21, 2015


EAST SIDE: Weeds coming back in between the Stipa, mostly red brome, due to the lack of wildflowers and non-grass natives, with the exception of the amsinckia making its first appearance. 56% Stipa and 4% Amsinckia for the natives. Exotics were 22% Red Brome, 10% yellow star thistle,
4% Italian thistle, 2% wild oats, and 2% rose clover.

stipa Stipa

WEST SIDE: Mowed to 3 inches tall, Stipa cover increased to 62% but yellow star thistle now 36% and wild lettuce 2%. Some of the mowed Stipa plants are quite large, up to 8 inches across now. No medusahead or weedy bromes seed. Big empty spaces between Stipa plants allow the weeds to get a toe-hold.


Native tarweed a few miles north, August 2015.


Exotic Stinkwort along I-5 near the town of Dunnigan

On the horizon just a few miles north of this site, are two members of the sunflower family, whose members will fight a battle for control of this site in the future. The native hayfield tarweed vs. the exotic Stinkwort. It will be very interesting who will win.

Update August 23, 2017

East Side test plot, what a mess, now 78% weed cover, with wild oats, 8 foot tall wild lettuce and medusahead grass, and 22% cover of Stipa plants.

West side test plot, even worse than the East side, with 92% weed cover mostly yellow star thistle, and only 8% Stipa cover.


 West Side % natives

 East Side
% natives


























N/M = Not Measured

CONCLUSION: UC Davis Project Sets the Price of replanting a California Grassland habitat

The results of the UC Davis project, funded by Caltrans, has set the price of replanting a low-elevation non-riparian native California grassland from scratch,
after many years of attempts.

UC Davis tried to get two acres of California native grasslands established from scratch, but without using any licensed native grassland restoration processes nor inventing or using any successful licensed ecological restoration technologies. Instead the project used the currently available public-domain restoration technologies.

Using public domain technologies, and possibly adaptive management techniques, the costs planting a low-elevation, non-riparian grassland in California has been effectively set by the results of this project at $245,000 per acre, taking over a decade to produce a stable 60-85% native cover.

The results of this study may have significant impacts on grassland mitigation projects around the State that are being currently conducted by CALFED, the U.S. Bureau of Reclamation and other agencies, The Nature Conservancy in managing land that they own (TNC), and the various Habitat Conservation Plans (HCPs) and other permits and Section 7 mitigations around California that require native grassland restoration.

If the best agricultural university in California cannot permanently repair an arid ecosystem like a native Western grassland for less than $200,000 per acre, why should developers, grazing permittees, pipline companies, or miners be allowed to destroy any more native grasslands, until we have the scientific knowledge on how to restore them at a reasonable cost?

Caltrans Caltrans
Another series of first-attempt plots, along I-80:
A second Caltrans native grass test plot is along I-80
near Dixon, photographed March, 2003., both sides of the Interstate in the shoulder. Photos show native grasses, drill-seeded and a few inches tall.

Caltrans Caltrans

These I-80 test plots were half-way between Midway Road exit and the Dixon West "A" Street exit.If you are traveling eastbound from Vacaville, the plot was 1.3 miles past the Midway Road exit, after where the high power line crosses, and before you get to a line of trees and the Phone Call box 80-342.

Traveling Westbound from Sacramento,
past the Dixon exit, the test plot started at the Vacaville/Fairfield/San Francisco mileage sign and Call box 80-343 (PM 34.00) and went toward where the high power lines cross the Interstate.

By October 2003, these I-80 plots were abandoned. Checking either side of I-80, there was little or no survival of the native grasses, and there was no evidence that another attempt was going to be made to succeed here.

This $90,000 per year, 5-year grant is Caltrans second major contract in the agency's history to study the conversion of roadside exotics back to local native plants. Details of the grant can be seen at

Other links:

---See other State DOTs research with roadside natives:

---See other State DOT web pages on native plants:

---See what questions need answers before native plants for roadsides can begin:

---See what type of roadside problems that native plants may be a solution (erosion, exotics):

---See what research and technologies are necessary for successes with roadside native plants:

---See a checklist of ten items to get faster successes:

Other Caltrans Roadside Vegetation Programs:

Photo June 2004.
Caltrans has an "Adopt-A-Highway Program", and each of the 12 Districts have District Coordinators, plus a printed handbook---Chapter ten is "Wildflower Planting". Participants of the Wildflower program agree to plant wildflowers on a minimum of three acres of highway right-of-way and establish them for a minimum of two years. "Wildflower courtesy signs" are placed by Caltrans with the name of the company or group involved in the planting.

The "Wildflower Planting" program's desired result? Perhaps that Caltrans hoped for when the program was initiated, was adoptees might develop at no cost to Caltrans successful "wildflower" roadside vegetation with low maintenance costs, better than the flammable annual exotic grasses and exotic weeds normally along California's roadsides?

Unfortunately, none of the California native "Wildflower Plantings" over the last decade, seem to be successful, and driving up and down the State you will see numerous "Wildflower" signs, with no fields of California native wildflowers at the various sites. The program has resulted in providing cheap advertising for companies, without the companies having to pay the minimum of $200,000-500,000 per acre that a successful wildflower planting in California could cost, as the UC Davis project has established.

Caltrans' "Wildflower Planting" program should be discontinued state-wide, until the costs of successfully establishing a wildflower planting drops into a price per acre that civic groups or commercial businesses can actually afford.

Updated August 27, 2017. Back to Craig Dremann's main Contents page.