Prevention and Control of Top 7 Invasive Weeds

The top 7 invasive weeds that we highlight this month are predators that will leach water and nutrients from your desired plants.  Some of them are highly flammable.  Our treatment recommendations for getting rid of the top 7 emphasize the least toxic practices.

Getting rid of these weeds is a combination of mechanical or biological means. 
Although Integrated Pest Management (Best Practices) sometimes requires a chemical solution.  Seriously, they are tough t to control.  Consult a professional if possible.

Because the weather is already warming and experts forecast a dry spring, this is the time to remove them. Fire district warnings may come sooner than expected.

What are invasive weeds?

This definition is based on their real threat to native plant and animal communities.  Their impact includes the risk of fire, flooding, and the potential to lower land value.

What are noxious weeds?

One weed on our list is considered noxious.  This term is a legal one used by state regulatory agencies.  A weed is categorized as such if it poses a threat to agriculture or plants and enables the agencies to ban, quarantine, or eradicate them.

The First Line of Defense is Maintenance (Prevention)

The Top 7 Invasive Weed Types

You may notice some weeds entangling their branches around your desired plants, or growing in the middle of them. It may take time to trace their branches to get to their roots. 

Some are flammable – noted in red below.

Broom Species (French & Scotch) Fire Hazard

French or Scotch Broom

French or Scotch Broom

Plentiful in forests, wooded areas, and roadsides. They spread along roads and appear like small trees.
Despite pretty flowers, they are toxic to humans and animals.
Crowds out desirable species by leaching nutrients.
Seeds spread by wind.

With a hot dry summer forecasted, get rid of these now.
Treatment Options
Hand pull between January-May

Cut and treat with an herbicide

Fennel or Licorice Plan – Fire Hazard



Seeds spread by wind and compete with other plants for nutrients.
They will displace native plants in coastal areas.

Treatment options
Hand pull when soil is still wet.
Dig out as much of the root as possible with shovels, hand picks.
Mowing needs to be done at the right time or will encourage seed growth.

Bull Thistle
Bull Thistle

Bull Thistle

A noxious weed.  Toxic and difficult to control once established.
Showy purple blooms and sharp needle-like leaves.
Grows where the soil is disturbed. Spreads rapidly up to 6 feet.
Aggressively leaches nutrients from desired plants.

Treatment Options
Dig out with a shovel making to get the root before pulling.
Mow before they flower.
California Invasive Plant Council says herbicides are effective.

Cape Ivy
Cape Ivy

Cape Ivy

Poisonous, toxic, and aggressive.  Will reduce habitats for pollinators.
Forms a dense blanket over desired plants. Its weight can cause a tree to fail.
Distinguishing from less invasive ivy is difficult. 
They choke off nutrients from understory vegetation, harbor rats, and snails.

Treatment Options
Requires precision as every stem must be removed.
Removing around the perimeter of a patch.
Because removal is complex cutting and using herbicide may be advised.

It may also require multiple treatments.
Best to use a professional.

Himalayan Blackberry – Fire Hazard
Himalayan Blackberry

Himalayan Blackberry

Don’t confuse this with native blackberries!  Natives are smaller and don’t tangle and sprawl.
Himalayan Blackberry grows relentlessly in dense thickets, covered in thorns. 
Highly aggressive, invasive, and difficult to
control. Displaces native species.
They leach out nutrients from desired plants, their thickets can block the sunlight they need.

Treatment options
Mechanical – dig up by root ball.
Burning of mature plants only with consultation with a professional.
Unfortunately, treating with concentrated herbicide is one of the most effective options.

Periwinkle or Vinca Major

Vinca Major

Vinca Major

Vinca Minor is okay! The two types look a little different.
Vinca Major leaves are broader, larger; heart-shaped.
Major is considered invasive because it is aggressive and outcompetes natives, leaching soil nutrients.
It spreads rapidly in shady creeks; drainage areas. 

Treatment Options
Hand pulling will work if roots are not deep and soil is loose and moist. (Then put plants in a plastic bag & destroy)
Mechanical means (put plants in a plastic bag and destroy).
Foliar spray can work.
Cutting and treating with an herbicide is effective if all else fails.

Ice Plants

Ice Plant

Ice Plant

When established, they form a dense mat that can choke out natives and destroy soil chemistry.

This mat can harbor rats and accelerate erosion.
Seeds are prolific. They move from landscaped to natural areas and devastate their ecosystem.
Pieces of the plant can be washed into storm drains.
One study found that when an ice plant was removed, both native and exotic plant species returned.
However, the natives were less abundant.

Treatment Options
Having shallow roots, hand pulling is effective, just do it early.

Closing Note

California Invasive Plant Council has taken the lead on public and professional education, and the eradication of invasive plants. 
They developed a comprehensive inventory of these plants and have initiated multiple plant control projects throughout the state. 
As they are a non-profit they rely on funding and volunteers for them. 
Their website is a great resource if you want to learn more.

Sources and Resources

California Invasive Plant Council (Cal-IPC)

UC Master Gardeners

California Native Plant Society (CNPS)






Landscape drainage problems like standing water in your yard, deck, hardscape, and around your building or house can be a nightmare!

Let’s talk about it. There are some great solutions for drainage issues.  Ones that work best with Mother Nature, whether you have a yard or a commercial property. 


Landscape Drainage Problem

Landscape Drainage Problem

Signs of a Landscape Drainage Problem

If you notice these you probably have a drainage problem.

  • You have a mosquito or other insect problem.
  • Soil is wet for prolonged periods of time.
  • Moss growth.
  • Plant material that appears unhealthy or stunted.
  • Exposed tree and plant roots.
  • Soil erosion.
  • Severely compacted soil.
  • Uneven or cracks in hardscapes or paved areas

We recommend the 7 drainage solutions below.  With a description of how they work.  Do yourself a favor, talk to a professional with the experience and equipment to do the work right.

7 Drainage Solutions

French drains

Type of drain: subsurface

It’s basically a trench filled with gravel or rock and contains a perforated pipe designed to address subsurface water.  A French drain in your yard or commercial property will redirect surface water away from its foundation to landscape beds or other areas that need water.  Consider this if
Water is pooling near the foundation of your building
Your soil excessively compacted.

French Drain

French Drain

Catch basin or storm drain

Type of drain: subsurface

One of the best investments you can make to your landscape drainage system.  It moves water fast.  Keeps it away from your structure, or from pooling in your turf or planted areas.  Catch basins have a grate on top and an underground drainage pipe that slopes away from the basin. They are often installed in turf or hardscape areas.  Periodic maintenance involves both clearing out debris and sediment underneath the grate and flushing it out of the pipe.

catch drain

Catch Drain

Channel Drains (also called a trench drain)

Type of drain: surface

It moves water through an underground drainage system.  Channel drains are long and narrow (see below) and are often used to protect hardscape from expensive water damage.  Tip – keep the surface around the drain clear of debris so the water can flow unobstructed.

Channel Drain

Channel Drain

Bioswales (also called dry creek bed)

Type of drain: surface

A shallow trench designed to direct stormwater runoff from one area of a property to another.

Installing plant material, rock or mulch will slow the movement of stormwater filtering it from harmful chemicals.  They typically have a drain at one end to take away water that doesn’t infiltrate.  Bioswales can also help recharge groundwater.  See the photo below of a GGI project in Santa Rosa.




If there are uneven surfaces in your landscape, it can cause water to start pooling in the landscape or around the perimeter of your building. Re-grading is another solution.  It’s the process of leveling out the land, redirecting rainwater, away from your building or paved areas. 


Grading in progress

Improve Soil Structure – for compacted soil 

Severely compacted soil (see below) will result in poor surface drainage in turf or landscape beds.  Its cause can be clay soil, heavy equipment use, foot traffic, or excessive tillage.  This will constrict soil pore spaces making them unable to absorb air or water.  One solution is to amend the soil with products like compost, worm castings, or other organic materials.  This will boost the population of microorganisms that are needed to create larger pores. The consistency of healthy soil is loose and crumbly and teeming with microorganisms.  Use the image below as a guideline.

Healthy Soil

Healthy Soil

Permeable hardscapes

Also called pervious (concrete) paving. Cheaper than standard concrete paving, more attractive, and better for the environment!  Plus, developers and designers love it.  In fact, it’s listed as one of EPA’s Best Management Practices.  Being porous, rainwater will drain directly into the soil, naturally filtering it, before running off.  Perfect for patios and driveways.

For more details, see our previous post on permeable pavers.

Prevent Problems by Managing your Drainage System

Be proactive.  Learn what to look for.

If you have a landscape contractor, make sure they understand how to spot drainage problems in the landscape.  A simple example – keep your soil from becoming compacted by regular aeration (if you have turf) and regularly input organic products to maintain its healthy structure.

And, call us with any questions.

Wishing you safety and good health.

(510) 439-3700

Joy comes in red, white, burgundy, and pink!

You’ve had a tough year.

Let some fresh Poinsettias help you celebrate the holidays with well-deserved cheer.

These classic Poinsettias arrive in a decorative foil sleeve.  If you like, we will maintain them through the holidays, or you can maintain them yourself.

Limited quantities are available.  Order today.

Your poinsettia order options

With or without maintenance
Sizes 4”,6” 8” or 10″ Poinsettia.
At this time 8″ or 10″ only come in red.
Our maintenance period is from November 28th through the first week of January.

Safe delivery during COVID-19

Our staff follows all safety protocols including social distancing, wearing masks, frequent handwashing, regular cleaning, and disinfection.  Our vehicles are cleaned between delivery routes.

How to maintain Poinsettias.   

Poinsettias are temperamental and need just the right light and moisture to last through the holidays.  Professional maintenance is the best option, but we understand we’re living through unique times.

Some tips on maintaining Poinsettias

  • They like indirect light for at least six hours per day.
  • The ideal room temperature is 68-70 degrees F.
  • Water thoroughly when the soil feels dry to the touch. 
  • They don’t like cold drafts (below 50 degrees) or excessive heat.

How to order

Contact Angela Wrath

Phone (510) 439-3707

Email awrath@gardenersguild.com

Read more

In these uncertain times, more people are finding solace in the garden.  Growing edibles surging in popularity. Plants and seeds are flying off the shelves of garden centers.  That leads us to water.  SF Bay Area Water Districts are eager to help you save money on water-saving irrigation equipment, drought-tolerant plants, and lawn conversion. How often do you hear that?

I compiled a list of Counties and districts with links to rebate requirements – everything you need to know.  The rebates apply to both commercial and residential accounts. Scroll down for a downloadable report.

Alameda County Water District (ACWD)
Note: due to COVID-19 rebate programs may be delayed by 1-2 weeks.


New! Rachio Smart Sprinkler Controller Instant Rebate (for residential customers)

Rebate for converting their lawns to water-efficient landscapes.*

$1.00/sq.ft of lawn converted. Please contact us to learn more.

*To be eligible for this rebate, customers must be pre-approved by ACWD, so please check with us first before beginning your landscape conversion project. Rebates are issued on a first-come, first served basis. Funding is limited. For additional lawn replacement ideas, please visit LoseYourLawn.org. 

For additional lawn replacement ideas, please visit LoseYourLawn.org.

Application Materials

Application – Please EMAIL this application to cons@acwd.com



Weather-based “smart controller” rebates

Commercial and large landscape customers that replace their existing conventional irrigation controller with a “smart” irrigation controller may qualify for a rebate of up to $30* per active station. See our Program Brochure (PDF) for more information. Sites must be pre-qualified – Please contact us for more information about how to get pre-qualified.  *Rebate is based on the number of active stations of each existing controller.

Contra Costa Water District (CCWD)
Note: Rebate programs and inspections could be delayed due to COVID-19.


Lawn Conversion rebate

The rebate is $1 per square foot of lawn replaced up to the maximum amount. 

The maximum rebate for single-family residential sites is $1,000.

The website has checklist and detailed list of restrictions.

Weather based smart irrigation controller rebates

$12 per active (used) irrigation station (zone) up to 50% of the list cost of the controller(s). Limit one rebate per customer per address. Limit one controller rebate per customer per address without pre-approval. Multiple controllers per address may be allowed on a case-by-case basis. Pre-approval is required.


Lawn Conversion rebate

The rebate is $1 per square foot of lawn replaced up to the maximum amount. 

Maximum commercial, multi-family, and municipal accounts is $20,000 per site.

The website has checklist and detailed list of restrictions.

Weather based smart irrigation controller rebates

Rebate is to upgrade conventional controllers to WaterSense certified smart irrigation controllers only.

$20 per active irrigation station (zone) not to exceed 50% of the list price of the controller.

water graphic

East Bay Municipal Utility District (EBMUD)
Note: Due to COVID-19 there will be a delay in responding to and processing mailed-in rebates. For a faster turnaround, please email your rebate application to waterconservation@ebmud.com


Lawn Conversion rebate

Up to $2,000 (single-family and small multi-family homes)

Irrigation Equipment rebate

Up to $2,000 for equipment that includes:

  • High efficiency nozzles
  • Drip irrigation conversion
  • Pressure regulators
  • Self-adjusting controllers
  • Irrigation sub-meters


Lawn Conversion rebate

Up to 15,000 (commercial and large multi-family properties) 

Irrigation Equipment rebate

Up to $15,000 for commercial or large multi-family properties.

Equipment includes:

  • High efficiency nozzles
  • Drip irrigation conversion
  • Pressure regulators
  • Self-adjusting controllers
  • Irrigation sub-meters

North Marin Water District
North Marin Water District has several rebate programs available including a Cash-for-Grass Turf Rebate, a Water Smart Landscape Rebate, and a Weather Based Irrigation Controller Rebate.


Cash for Grass

$50 per 100 square feet of lawn area.  Limited to total of $400 for single family dwellings. 

Requirements include:

  • Replace the regularly mowed and automatically irrigated lawn with California native low water use plant material (see District Approved Plant List or Sonoma Marin saving water partnership list).
  • Mulch new landscape to a depth of at least 4 inches.
  • Agree not to re-install irrigated turf in the project area.

Water Smart Landscape Rebates

Rebate amount: 50% of the actual cost of District approved items, up to a maximum of $100 for residential customers.

Equipment that qualifies includes:

  • Drip irrigation systems
  • Water pressure-regulating devices
  • Check valves
  • Multi-stream rotating sprinkler nozzles (for lawn areas only)
  • Rain shut-off devices
  • Mulch

Weather Based Irrigation Controller Rebate*

$100 or $30 per active station up to $1,200 per controller, whichever is greater.

List of eligible controllers includes: Weathermatic, ET Water, Rainmaster, Hunter, Toro, Rainbird.

*Note: does not specify whether it is residential or commercial

MULTI-FAMILY DWELLINGS (they do not have a commercial category for rebates) 

Cash for Grass

$50 per 100 square feet of lawn area.  Limited to total of $100 for townhouses or condominiums, $50 for apartments.

Requirements include:

  • Replace the regularly mowed and automatically irrigated lawn with California native low water use plant material (see District Approved Plant List or Sonoma Marin saving water partnership list).
  • Mulch new landscape to a depth of at least 4 inches.
  • Agree not to re-install irrigated turf in the project area.

MMWD (Marin Municipal Water District)
They offer rebates for either residential or commercial property.

Smart Irrigation Controller Rebate – up to $100 for both residential or commercial

Landscape your lawn – (LYL) Turf Replacement Incentives – for residential or commercial

LYL Option 1: Rebate of $1/square foot of lawn replaced
Customers are reimbursed costs based on receipts submitted for eligible expenses, which include sheet mulching materials, drip irrigation components, and climate-appropriate plants.

LYL Option 2: Free sheet mulch material (cardboard, compost, mulch) and delivery, plus a free irrigation conversion kit
This option provides all the materials necessary to remove your existing lawn using a sheet mulch approach, as well as a component kit to convert existing overhead spray irrigation to high-efficiency drip irrigation.

Solano County Water Agency


Smart Irrigation Controller Rebates

Rebates from $300, $700, or $1000 depending on the number of stations.

Link above has details or call 855-512-1221 for complete program details and to apply for the rebate. 

Water Efficient Landscape Rebate (program has been cancelled until further notice)


Smart Irrigation Controller Rebates

Rebates from $300, $700, or $1000 depending on the number of stations.

Link above has details or call 855-512-1221 for complete program details and to apply for the rebate.


Many Bay Area cities offer landscaping water conservation rebates. Below is a list of cities that offer these rebates:

Santa Rosa Water District
Both residential rebates and commercial rebates for turf replacement, irrigation efficiency improvement, and rainwater harvesting.


Cash for Grass

$0.50/sq. ft. up to max of 500 sq. ft. or $250.00

For more information and requirements. 

Irrigation Efficiency

up to $100.00 max for pre-qualified equipment/hardware

Equipment includes water conserving controllers.

For more information and requirements. 


Cash for Grass

$0.50/sq.ft.up to max of 5,000 sq.ft. or $2,500.00

For more information and requirements.

Irrigation Efficiency

up to $1,000.00 max per meter for pre-qualified equipment/hardware

Equipment includes water conserving controllers.

For more information and requirements.

City of Petaluma
The city of Petaluma provides Commercial, Industrial, and Institutional accounts as well as Multi-Family Residential accounts.  (No commercial rebates listed on the website)


Smart Irrigation Controller Rebates.

up to a $900 rebate for the purchase of a Smart Irrigation controller.

Download the Report


We are well into May – the official start of fire season.  It may be hiding behind the coattails of COVID-19, but we know it’s here.  In spite of recent rains (which we are grateful for), temperatures will heat up and dry weather will prevail for the next several months.

Like clockwork the call volume at Gardeners’ Guild’s has spiked with requests for weed abatement.  This is vegetation management – an essential part of fire prevention – and our topic for this month.  Our forty-plus years of experience managing vegetation inform this month’s content and make us a valuable resource for you.

A note about the pandemic and Gardeners’ Guild’s status

We are open now – since the state has determined that landscape activities are essential.   I hope this post finds you well. Please call us with any questions about our policy. 
(510) 439-3700.

As if you aren’t dealing with enough – the shock and overwhelm of a pandemic thrust upon you. Now, Californians, we enter summer with fire prevention added to our to-do list. 

This post is focused on vegetation management and its role in preventing wildfires.  We help you navigate this with simple and easy-to-digest basics. 

I’ve synthesized the essentials.

  • What vegetation management is, why it’s important now and actions you can take to minimize your risk of wildfire.
  • Scroll down to see a great video on Fire Wise landscaping and links to several county resources.
Tall Weeds

Combustible Weeds

Why is this important now?

Wildfire season 2020 threatens to be longer, with bigger fires unleashing more devastation.  Being educated and taking appropriate action now will help protect your investment, family, and neighbors.

Daniel Swain is a UCLA Climate Scientist and author of WeatherWest.com.  He studies extreme weather events and their causes.  I began following Swain during the drought and was in awe of his spot-on analysis of weather events. 

In a recent post on weatherwest.com, Swain said:

“the NIFC* is predicting a higher than average likelihood of large wildfires across NorCal by mid-summer–and I would expect that ultimately to be true into the autumn as well.” *NIFC or Nation Interagency Fire Center is a support center for wildland firefighting, located in Idaho. 

You may notice that your local fire department is requiring more engagement from you this year.  I’ve noticed some are scheduling inspections and amplifying their public education efforts.

Fiery sunsetNorth Bay Sunset – October 2017

The 3-R’s of Vegetation Management

Vegetation management is the process of controlling plant material to minimize the risk of fire ignition and spread. 


Of dead fuels (vegetation), weeds, brush, invasive species and plants deemed a fire accelerant. 


Thinning heavy brush and trimming trees.  Crucial to reducing the spread and intensity of a wildfire.
Pruning shrubs and trees will provide adequate separation between them and away from your structure. 
Check with your local fire department for plant spacing requirements in your area.  The section below has a link on spacing tips for properties on a slope.


Replace with fire resistant plants.  These plants should be non-oily, deciduous or have higher water content.  Make sure they are free of dead wood and well hydrated. 

Below are links to great tips including fire resistant plants

Steep Slope

Steep Slope in the North Bay

How to manage your vegetation depends on its location

Is your property in an at-risk area?
Check on the latest guidelines from your municipality or county.  They’re changing as the threat of wildfire becomes more extreme.  Below are tips for assessing your property’s wildfire risk.

Advice from Contra Costa County’s Wildfire Protection Plan
“Rigorous oversight, active management, and an adaptive approach are required to achieve fuel management goals.”

Especially at risk are WUI or Wildlife Urban Interface areas
Areas, where wildland and residential communities intersect, are at risk for wildfire.  Categorized as “high” or “very high” risk.  Contributing to this is a trend toward building more homes adjacent to open space. 

Parts of Marin, Contra Costa, and Sonoma Counties are considered “very high” or “high” risk. 

Is your property on a hillside?
Wildfires on a slope burn more rapidly and longer flame lengths than along flat ground.  The steeper the slope, the more quickly it will travel. 
Clearance between shrubs should be 4 to 40 feet depending on the slope and size of vegetation. 
Assess your property’s risk of wildfire exposure by looking at the slope of the land around your commercial building or home and the direction your building faces.  See these tips from FireSafe Marin if you are on a slope

Vegetation Management Activities

Manual – hand pulling or cutting

For smaller areas, this is sometimes preferred for removing the weed’s roots.

Mechanical treatments

Such as mowing of weeds
Selective tree removal

Chemical treatments with herbicides

The least desirable method, but sometimes warranted for large areas as part of an integrated pest management (IPM) plan. For weeds that are invasive and combustible.

Fire Break Work

Work usually performed on a hillside with equipment that creates a non-flammable gap between vegetation, acting as a barrier to stop the progress of a fire.

Managed Grazing

Generally used for large areas for fire breaks and to clear combustible weeds. Goats, miraculously suited to the job, forage for low lying grasses, weeds, trees, shrubs, branches and invasive vegetation.  They can also reach upwards of 4 to 5 feet to eat tree branches, which reduces “ladder fuels” and helps to slow spreading of a fire.  It’s a cost effective, environmentally friendly option and a joy to watch. 

Controlled Burns

The state of California says this about controlled burns:
“Sometimes called a controlled burn or prescribed fire, prescribed burning is one of the most important tools used to manage fire today. As catastrophic wildfires continue to be a growing concern in California, the use of prescribed burning to reduce hazardous fuels is projected to increase. Daily burn decisions are issued based on the forecast of air quality and meteorological conditions that can affect smoke dispersion.”

Managed Grazing

Managed Grazing Project

What you can do now

Know your property and its risk of wildfire
Make sure you have the most up to date information from your local fire department.  (See below for links).

Create a vegetation management plan that consists of the 3-R’s mentioned above
For removal or thinning, hire a landscape professional or an Arborist.

Begin defensible space planning
The links below have the latest requirements on defensible space.
We will also cover this topic in the summer.

Inspect your property
A letter to the Marin IJ’s editor, written by a Fire Ecologist has tips I wanted to pass along. He suggests that people still stuck at home could examine their property for dry debris within five feet of a structure’s foundation, especially under wooden stairs and decks.  The reason – embers from approaching fire target these areas. 

Call us with questions about vegetation management to prevent fires. 
(510) 439-3700.

See the video below on Fire Smart landscaping, narrated by a local Master Gardener.  Below the video are links for you.

The links below have the most up to date guidelines on reducing your risk. 

Wishing you good health.