bullthistle


Prevention and Control of Top 7 Invasive Weeds Using the Least Toxic Practices

Our report on the top 7 invasive weeds in the SF Bay Area was re-worked from one I posted in 2016 weeds typical in the San Francisco Bay Area including the most invasive weeds.

The top 7 invasive weeds is focused on the worst for good reason. This summer promises to be hot. Some of the top 7 are highly flammable.  Our treatment options for getting rid of the top 7 emphasize the least toxic solutions. Hand pulling or mechanical means for some, at the right time, can be effective.

Our Recommendations

We suggest a combination of prevention, mechanical or biological means. 
Sometimes a chemical solution is necessary, but only that is so.
The results of 2018’s on and off rainfall and intermittent heat waves have seen a prolific  crop of bull thistle (pictured above) and oxalis.

See the full report on managing weeds. It includes 13 weed types, prevention and control.

Download

Prevention – the First Line of Defense

Plant Choices
The right plant in the right place sounds simple but makes all the difference. 
Healthy vigorous plants have the best chance of out-competing weeds.  
Healthy Soil
Make sure that plants are healthy by feeding the soil with organic products including mulch and compost.
Mulching and Sheet Mulching
Mulch keeps soil cool and moist.  It deprives weeds of light.  Organic mulches enhance soil structure and host insects which will devour weeds.  Sheet mulching is layering of cardboard, newsletter or fabric.  It serves as a weed barrier.  Water Management
Proper irrigation is critical.
We recommend drip because the water goes directly to the root of the plant, not in between them. Spray irrigation can encourage weed growth.  

The Most Invasive Weed Types

Source: California Invasive Plant Council

Remove these plants from your garden! 
They damage our ecosystems by leaching nutrients from native species.
Some are highly flammable and at the same time consume valuable water.

Broom Species (French & Scotch)

Plentiful in forests or wooded areas. They spread along roads and appear like small trees.
Despite their pretty flowers they are toxic to humans and animals.
BEWARE. They are fire hazards. With a hot dry summer coming , get rid of these.
Crowds out desirable species by leaching nutrients.
Seeds spread by wind
Treatment Options
Hand pull between January-May

Cut to just above ground
Cut and treat with an herbicide

Fennel or Licorice Plant

Seeds spread by wind and competes with other plants for nutrients.
They will displace native plants in coastal areas.
BEWARE – This plant is also considered a fire hazard.
Treatment options
Hand pull when soil 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

Showy purple blooms and sharp needle-like leaves.
Grows where soil is disturbed. Spreads rapidly.
Leaches nutrients from desired plants.
Treatment Options
Hand pull and step on stem before pulling
Mow before they flower
Herbicides

Cape Ivy

Forms a dense blanket over desired plants.
Distinguishing from less invasive ivy is difficult.
They choke off nutrients from understory vegetation, kill trees, 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.

Himalaya Blackberry

Don’t confuse this with native blackberries!  Natives are smaller and don’t tangle and sprawl.
The
Himalayan Blackberry grows in dense thickets, covered in thorns. 
Highly invasive and difficult to
control.
They leach out nutrients from desired plants and shade out light.
BEWARE they are also a fire hazard
Treatment options
Mechanical – digging up root tall
Burning of mature plants only with consultation with a professional
Unfortunately, treating with concentrated herbicide is one of the best ways.

Periwinkle or Vinca Major

Vinca Minor is okay! The two types look a little different
Vinca Major leaves are broader, larger; heart shaped.
Vinca Minor leaves are smaller, elongated.
Major is a pest. They root wherever their stems touch soil.
They spread rapidly in shady creeks; drainage areas.  And, they choke off natives.
Treatment Options
Hand pulling will work if roots are not deep, soil is loose and moist. (put plants in plastic bag & destroy)
Mechanical means (put plants in plastic bag and destroy)
Foliar spray can work
Cutting and treating with an herbicide is effective if all else fails.

Ice Plants

Competes with native plants.
Seeds are prolific. They move from landscaped areas to natural areas.
Pieces of the plant can be washed into storm drains.
They form a dense mat which can harbor rats and contribute to soil erosion.
Research has shown that where they root, ice plants make long term changes to the soil.
A snippet from one study found that when the ice plant was removed both native and exotic plant
species returned.  But natives were less abundant.
Treatment Options
Hand puling is effective, just do it early.

 

 

 

 

 

 

 

landscape drain

I’ve updated our post about drainage from March of this year.
We talk again about solutions to landscape drainage problems.
There is additional detail added including graphics that describe the drainage problems and solutions.
One of the solutions described below is a dry creek bed. It was a project of Gardeners’ Guild at Spring Lake Village.

1. Hardscape with Standing Water

Example of drain pipe clogged with tree roots

Includes patios, pavers, driveways, parking lots and steps.
If these areas have had standing water for some time it could be due to these issues listed below

Improper grading
Your hardscape may not have the proper slope and is directing water toward the building foundation. 

Blocked drains
Tree roots, leaves, mulch and other debris can blow into the drain from winds and rain

Corroded pipes
Over time, your drainage pipes deteriorate and will eventually collapse.

The Risks
Water can put your structure’s foundation at risk.
Storm water carries with it chemicals, debris, dirt, pesticides and other toxins.


Solutions for Standing Water 
Regrading.  Over time a property will settle.
Clear out drain grates and pipes (make a plan for their regular future maintenance)
Arrange gravel around the perimeter of drain grate to deter debris from blowing in.
On larger hardscaped commercial property areas more drains may be required.

2. Flooded Turf

Aeration process illustration

Above illustrates what aeration does

The culprit can be grading but a more likely offender is compacted soil.
Summer drought conditions and degraded soil will shrink pore space that normally accepts water and nutrients.
High foot traffic will also contribute to soil compaction. You can identify it by its hard surface.

Soil texture needs to be loose enough to allow water to pass through. Clay soil, common in the San Francisco Bay Area is the opposite!

The Risks
When water pools on top for a prolonged period, turfgrass will decline and rot.
You can observe it by smell – foul odor. 
You will also notice grey, red or orange spots and insects.

Solutions for Flooded Turf
Re-grading
Aeration. The soil is perforated which opens up its pores to allow nutrients and moisture. (See graphic above)
Build a dry creek bed.  It is a gully or a trench usually lined with stones and edged with plants to mimic the look of a stream.  They are beautiful and will help with drainage. See example below.

GGI dry creek bed project at Spring Lake Village, Santa Rosa

Dry creek bed under construction at Spring Lake Village Santa Rosa

3. Flooded Planter bed and other planted areas

 Example of flooded planter bed

A planted area or bed should be designed to allow the water to flow out and be distributed to other areas.  A proper slope needs to be calculated with a site level during the design process.

The Risk

Plant root damage will occur if soil is saturated for a prolonged period. When soil’s abililty to absorb water is tapped out it is considered saturated.

Solutions for Flooded Planter Beds

Re-grading will help with slope problem. Correcting this involves directing surface water to the lowest spot on the property which will empty into a drainage ditch, catch basin or well.
Good options include:
Creed beds (illustration above)
French drains
Bioswales. Increasingly popular and effective.  They are constructed to slow, collect infiltrate and filter stormwater.  They include a permeable storm bed. (See graphic below)

Bioswale illustration

4. Flooding Around Down Spouts

Solution to flooding around down spout

Example of re-directing down spout and into creek bed

This is a common problem.  In heavy rain down spouts can empty rainwater into the landscape.

The Risk

Your building’s foundation
Plant root damage, erosion and hardscape deterioration.

The Solution

A professional can re-direct the downspout.  A dry creek bed is an additional step to drive moisture away from your building.

Highway 37 and US 101 February 2017

The photo above is breathtaking reminder of the toll our rainy season has taken on San Francisco Bay Area residents.  El Niño surprised us with a ferocious encore performance. Many of our properties, roads and highways are still recovering.

Highway 37 is an extreme example of what happens when drainage fails.

Five feet of water flooded a 3-mile stretch of the highway after the heavy storms this winter.

Ditches on either side of the highway act effectively as drains, keeping water from flooding the road in a typical rainy season. But, this year, back to back storms prevented them from draining. Having no place to drain the overflow, efforts by Caltrans to pump the water out were stymied.    

An emergency solution included raising a portion of the roadway and fixing the drainage system by installing larger pipes, giving it greater capacity for moisture.  It seems to have worked. No unexpected weather has tested it yet, though.

Does your property have any areas of standing water, mulch that is washing away, soggy grass or mosquito problems? If so you probably have poor drainage that winter storms have exposed.

 


hardscape with standing water

Area 1

Hardscape

Includes patios, pavers, driveways, parking lots and steps.

If your hardscape has had standing water for sometime it could be due to these issues.

Improper grading. The photo on the right is an example of pooling water showing improper grading.

Blocked Drains  Debris, mulch or plant material could have gotten in from winds and rain.

The Risk

If the drainage problem is not resolved your structure’s foundation can be at risk.

Solution

  • Re-grading. Over time a property will settle.
  • Clear out drain grates and pipes. They should be maintained consistently. Laying down gravel around the perimeter of the drain grate can help in its maintenance.
  • Retaining wall. This can also resolve a slope problem.

 

Area 2

Turf

It can be also be improper grading.

But more likely it is compacted soil.

Previous drought conditions and/or degraded soil will shrink its pore space that normally allows water and nutrients. You can tell if soil is compacted because its surface is hardened.

Soil texture needs to be loose enough to allow water to pass through.  Clay soil, common in the San Francisco Bay Area, is the opposite.

The Risk

Water will pool on top and you will have soggy mess of plant material.  This is true of all plants.  They will decline and rot. 
You can observe this problem by its smell – foul odors.
By sight – grey, red or orange spots and insects.  

 

flooded turf

Solution

  • Re-grading can also help.
  • Aeration.  This is perforating the soil opening up its pores to allow nutrients and moisture.
  • Creek beds are another good solution.

Area 3

Planter Beds and All Planted Areas

A planted area should be designed to allow the water to flow out and be distributed to other areas.  Consider natural water flow.

A proper slope needs to be calculated with a site level during the design process.

The Risk

Plant root damage will occur if soil is saturated for a prolonged period. Soil is saturated when its ability to absorb is tapped out. 

flooded planter beds

Solution

  • If it is a slope problem, regrading will help.  Correcting a slope problem involves directing surface water to the lowest spot on the property which will empty into a drainage ditch, catch basin or well.
  • Creek beds, french drains and bioswales are great options!

Area 4

Gutter Spouts

A common problem.  If gutter down spouts are not properly installed they can empty rainwater into the landscape it will damage plant material and your hardscape.

The Risk

Your structure’s foundationPlant root damage, erosion and hardscape will be degraded.

flooded planter beds

Solution

  • Hire a professional to re-direct the spouts so the water goes downhill.

Hire a Professional

At the very least call one and discuss your drainage problems with them. 
Your plant material, trees, hardscape including driveways and your building’s foundation are too important.
Gardeners’ Guild has a construction division with many years of experience resolving all kinds of drainage problems.

Learn More About Drainage Systems

Descriptions of 5 Types of Drainage Systems

Pervious Paving – Pavers that will help with drainage and are sustainable!

 
rain-garden-graphic

Rain garden Graphic from Nature Conservancy

Indicators for the Northern California rainy season are uncertain. Although we’ve had heavy rain early in the season, and more is predicted in the next week, none of the long range weather modeling has been conclusive.  We can only hope for a wet winter. 

You can bet that there will be high winds, and heavy downpours this winter.  And, it can do damage and cause flooding if your drainage is not prepared.

What is drainage and why is it important?
When there is heavy rain, water infiltrates into the soil. Once soil becomes saturated and no more water can be absorbed, it begins to pool on the surface.

If the period of saturation is prolonged water will continue to flow into the deeper layers of soil damaging the roots of your plants.

Drainage is a system of removing excess water either from the ground surface or the rootzone.

Surface drainage is removal of water the ground surface

Subsurface drainage is removal of water from the root zone

Your drainage system will protect your building or house from costly water damage and plants from root damage. Have your drainage checked before winter.  Below we drill deeper into methods of drainage.

Soil Drainage

Most plants need soil that drains well.  That refers to soil whose texture is loose enough to allow water to pass through.  The characteristics of clay soil, which is common in the San Francisco Bay Area, are unfortunately, is the opposite. Compacted soil has the same problem. Heavy rain can cause plant decline and rot.  You can observe this problem by its smell – foul odors. By sight – grey, red or orange spots and insects. 

The solution to soil draining problems:
Organic amendments will improve soil structure.  Inorganic amendments like sand can also be added along with other components.  It is best to rely on a professional who can advise the right combination of ingredients.  2” of mulch also can help at least 2” of mulch over the landscaped area around your house or building.  It will help your property absorb rain more safely in addition to cutting down on erosion or immediate runoff.

Grading To Correct Slope

The ground should slope away from your home or building instead of toward it.  Water runs more quickly down a slope, particularly a slope of clay soil.  The soil surface should not be above your foundation.

The solution grading issues:
There are a number of strategies depending on the property. Trimming back landscape overgrowth on a hillside or low lying area is one.  Grading may be required.  This involves directing surface water to the lowest spot on the property which will empty into a drainage ditch, catch basin or well.

Regular Testing of Landscape Drains*

Visually inspect.  Make sure they are all functioning. Leaves, roots and dirt and other matter can easily block a drain causing water to back up.  Storm water runoff from surfaces such as roofs, driveways and patios should be directed into a collection system to avoid flooding.  This will damage plant roots.

If your building or home does not have gutters or drains consider having them installed.

Proper Retaining Walls

If your property is on a slope a retaining wall could be essential erosion protection.  Make sure to hire a knowledgeable professional to understands its proper construction and drainage as well.

*Types of drainage systems

Catch Basin
A surface drain.  It collects and traps debris in storm drains and prevents it from entering drainage pipes.  
 
Channel Drains
A surface drain. Long narrow strips used between main structures and paving at the edge of a patio or deck
 
French Drains
For patios, decks or walkways so that water is sloped toward them or into landscape beds. Drain covers are usually made of metal or stone.
 
Swales
Shallow trench that carries runoff away from building to municipal drains or ditches.
 
Rain Gardens
Shallow, bowl shaped depressions that are densely planted with flowers, grasses and other plant material. Rain gardens will collect runoff from gutters, roofs, decks and other surfaces. Water percolates gradually into the soil and is absorbed by the plants. Rain gardens also help prevent ground and surface** water pollution.
 

 

 

 

 

budgetart

If you are a Property Manager, you are likely knee-deep in budget season

Remember that landscaping can increase the value of a house from 5% to 12.7%.  On a $400,000 home 5.5% is $22,000; 12.7% adds $50,800.*  Conversely, a degraded or disorganized collection of plants detracts from a home or commercial building’s value.  Bob Vila says that the biggest mistake homeowners make is a lack of a coherent plan. Similar for commercial properties and residential communities.

With the long term in mind, make sure you have these 4 categories covered in your landscape budget for 2017.

Landscape management:

  • Allow for materials cost increases for items such plants, including annual color; mulch.
  • Mulch replenishment is important. It has a neat appearance and helps soil hold water.
  • Annual color replacement
  • Allowance for IPM (Integrated Pest Management) treatments
10784water_splash

Irrigation upgrades and repairs**

  • An irrigation system installed more than ten years ago may be wasting water and costing you money. Ensuring efficiency may mean replacing and repairing.
  • Smart (or weather based) irrigation controllers can also save up to 30% off your water bill.
  • Converting from spray to drip is something to consider for your budget.
  • State of the art precision spray nozzles can improve spray irrigation efficiency and save water too.

Large Tree Care

  • Routine pruning and fertilization are important for the health of your trees – an important part of your asset. Older trees may need more maintenance.  With proper care your trees will last many years.
  • A tree care plan will alleviate the stress of emergency tree work needs.

Landscape Improvements**

  • Turf care includes aeration and soil building or possibly overseeding.
  • Because of California’s ongoing drought and San Francisco Bay Area restrictions, you may consider converting turf to drought tolerant plants.
  • Consider converting annual color to more permanent perennial plant material.
  • The useful lifespan for large shrubs or small trees is approximately 7 to 10 years. When plants are past their useful lifespan they should be replaced with new plant material.

* Source: Hortculturalist Alex Niemiera of Virginia Tech researched the impact of landscaping on the value of a home. 

**Note: Depending on your location there could still be rebates available from your water district.