Why your weeds keep coming back

Have you noticed an abundant crop of weeds this spring?  One reason – the heavy rains of last fall and winter may have awakened long-dormant seeds.  Does it feel like the long rainy winter just erased all the backbreaking work you did last year?  Our guide to weeds includes the why what and how of managing weeds. 
Plus our guide to weeds is downloadable.  See link below.

Why do they reappear?

  • Weeds produce thousands of seeds.  Those seeds are stubborn and can be viable for years, even decades.
  • They are transported by weather, especially wind. Also by animals, humans, and water. Mulches and soil can also harbor weed seeds.
  • Even after weeding, their seeds will remain in the soil and may be dormant for years.
  • Perennial seeds are the hardiest.  Their roots are alive for many years and harder to kill than annual weeds.
  • An example of a perennial weed is a dandelion.  Just one dandelion puffball carries as many as 100 seeds!

Understanding is the key to managing weeds

They are tough and relentless. Weeds can thrive in the most unsavory environmental conditions. Drought, fire and even herbicide applications don’t kill all weeds.  And, they will outcompete with desired plants for sunlight, water, nutrients, and space. 

Weeds offer some benefits

  • Protect bare soil from erosion.
  • Improve the soil by imparting organic matter.
  • Absorb carbon dioxide from the atmosphere.
  • Can provide habitat for birds, worms, and beneficial insects.
  • And – some have powerful medicinal properties (and are edible)

Weeds are a problem when

  • They overpower desired plants and deplete the soil of nutrients and moisture.
  • Their unattractive appearance, texture, color and growth habit detracts from your garden or landscape.
  • They harbor disease-carrying insects that spread to desired plants.
  • Poisonous weeds can be dangerous to you and your pets.
  • Invasive weeds take over your garden in a single growing season.

Two types of weeds – what makes them different

Annual Weeds
Warm weather annual weeds grow only from seeds every spring.  Cool weather weeds germinate in late summer or fall. Their roots are shallow as compared to perennial weeds (see below). For this reason, they are easier to pull.  Some die out after flowering.

Perennial Weeds
These weeds reproduce year after year from roots and seeds.  Because of their tenacious roots and seeds that can live for years, they are much more difficult to control.  Two common perennial weeds in the San Francisco Bay area are dandelions and oxalis.

Tips for Managing Weeds

The harsh truth is that you can never completely eliminate weeds, but effective management will help control them. 
Your first step is prevention.

Tips on Weed Prevention

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 the soil cool and moist.  It deprives weeds of light.  Organic mulches enhance soil structure and host insects can devour weeds.  Sheet mulching is layering of cardboard, newsletter or fabric.  It serves as a weed barrier.
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.  
Pre-emergent Herbicides
There are products that range from natural to chemicals whose purpose is to control the germination of weed seeds. This product will not impact weeds that have already grown.  An herbicide is a barrier so it needs to thoroughly cover an area for maximum effectiveness.

 

How to get rid of them?

Gardeners’ Guild’s philosophy is to use the least toxic practices. We recommend a combination of prevention, mechanical, biological, and chemical means only when necessary.  

Hand Pulling
This works best when weeds are small and before they flower.  Once they flower, seeds will be spread.
String Trimming
This works best for annual weeds.  It is used for the top growth control of broadleaf weeds.
Mowing
For a heavily weeded area, mowing helps prevent broadleaf weed seeds from spreading but cutting off flower heads.
Flaming
Less effective for deep-rooted (perennial) weeds. This method requires a propane burner which burns cell walls of the seeds.
Post-emergent Herbicides
Their purpose is to kill weeds once they appear. This product will either target foliage and/or weed roots. Take precautions when using and be aware of any community regulations against them. 

 

Weed Types Common to SF Bay area

Below is a list of common San Francisco Bay area weeds.  Some are invasive and fire hazards.  Invasive weeds will damage our ecosystems by displacing native species, increase fire and flood danger and consume valuable water.
 
Ice plants – Invasive
They compete with native plants. Seeds are carried from landscape settings to natural areas. Pieces of the plant can be washed into storm drains. They grow in natural areas and along freeways. Remove by hand pulling, mechanical methods.  Glyphosate is effective but only as a last resort.
Oxalis/Wood Sorrel
Grows in lawns; flower beds.  Blooms in spring. Spreads rapidly by their many persistent bulbs. Very competitive. Remove root bulbs before they bloom.  Sheet mulching or post-emergent treatments are used.
Dandelion
Perennial. Seeds spread in wind. Leaches nutrients from the soil of desired plants. Prevention is key. Hand weeding and fabric mulching can work.  Herbicides if necessary.
Periwinkle/Vinca Major – Invasive
Their aggressive stems root wherever they touch the soil.  Spreads rapidly in shady creeks, drainage areas and chokes native plants. Vinca minor is okay.  Removal by hand pulling.  Rake the area to loosen the soil. Or, brushcut and cover area with cardboard for at least a year.
Licorice Plants – Invasive
Seeds spread by wind.  Spreading branches root wherever they make contact.  They can and do displace native plants in coastal areas. Hand pulling is effective for small infestations.  for larger areas, herbicides are used.
English Ivy – Invasive
Distinguishing them from less invasive ivy is difficult.  Invasive ivy will smother understory vegetation, wrap around trees and harbor non-native rats and snails.  Removal – wear protective clothing. Dig down 8-10 feet should get at their roots. Dispose of plants. A large expanse of ivy can be rolled like a carpet.
 

Download our report on Weed Management

 

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Gardeners’ Guild will deliver Poinsettias to your SF Bay Area office

Having Poinsettias delivered will put a smile on your face. 
Your office mates will thank you.

Our interior division services San Francisco and the East Bay as well as Marin, Sonoma and Napa Counties.

Limited quantities available.  Order today.

Your poinsettia order options*

Either with or without maintenance
Sizes 4”,6” 8” or 10″ Poinsettia in a decorative foil sleeve
We will maintain them from November 28th through first week January
*A delivery charge may apply.  Replacements are at an additional cost.

Colors

Red, white, burgundy and pink

What you should know if you want to maintain them yourself.  

Poinsettias are temperamental need just the right light and moisture to last through the holidays.  This is why having a professional maintenance is the best option, especially for a commercial building.

They need strong indirect light, love moisture but not too much and warmish temperatures.  Avoid drafty areas.  Keep them inside.

Poinsettias aren’t poisonous but they can cause mild irrigation in puppies or kittens.  Best to keep them away.

And, they won’t harm people.  An Ohio State University study found that a 50-pound child would have to eat 500 leaves for any harmful effect to occur.

How to order

Contact Angela Wrath

Phone (510) 439-3707

Email awrath@gardenersguild.com

Read more

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.

 

 

 

 

 

 

 

 

Sifting through a long list of 2018 trends in landscaping and gardening, we extracted ones more closely pertaining to the San Francisco Bay Area.

These important trends reflect our changing climate and how/ what people are planting this year. 
Plus there’s a brief, but inspiring case study about an old-fashioned practice made new again.

Thank you to our sources:
Sunset
Garden Design Magazine
Gardenista
Turf Magazine
Houzz
Land8.com
San Jose Mercury News

Container Gardening
A growing population millennials and retirees are moving into multi-family and tiny housing.  They want to garden. The answer to their small space challenge is containers.
They provide color, texture and structure.
There are a myriad of choices you can find from classic to modern.  Rustic to formal. Balcony boxes.
See below.

Do’s and Don’t’s on Containers
Say no to dark colors or clay pots
Dark colors get too hot; clay dries out in summer.
Best is fiberglass, plastic or glazed pottery.
Make sure they have drainage holes.

Succulents in glazed pottery

Low Water Container Perennials
Succulents are great. Hardy. They usually need full sun.
California Poppies are native, hardy and cheerful.
Lavender – Depending on your space you might try dwarf varieties.  They need full sun.

Kale

Kale

Edible Container Plants
Among the easiest to grow are –
Lettuces, kale and herbs. Shallow-rooted, they need a container with a 9-12″ depth.
Tomato plants are larger and need a container with a 12-14″ depth.
Consider dwarf varieties as well.

What You Need
Good soil.
Know your plant sunlight and water needs. Most edibles will need four-five hours of sun.
Mulching will help your soil hold water.
Feed the soil with: compost; worm castings.
(Gardeners’ Guild has great success with worm castings.  It is odorless, natural and improves soil health). There are also natural products you can purchase at your local nursery.

Acclimating Landscapes to Climate Change
More people are taking action to prepare for the effects of extreme weather such as drought, wind, severe heat, cold and rain.  Adapting a landscape for a changing climate involves components such as design, plant types, maintenance that includes consistent and correct pruning. 
Water management is also critical in acclimating our landscapes.
Below are tips on how to prepare for these trends, what you can do and why.

High Wind Resistance
Plants, trees and retaining walls are used as wind blocks
In large areas – plants are installed in a series of staggered rows that re-direct wind around and above.
For small areas – a similar concept referred to as a wind screen.
Wind isn’t completely blocked but tempered somewhat.
Wind Resistant Plant Attributes
More flexible stems.  Examples: Escalonia, Ornamental grasses.

Fire wise plants left to right: Agave, African Iris, Beach Aster

Fire Resistant Landscapes
The Napa and Sonoma fires brought into granular focus three factors:
“Defensible space” – a high priority.  The recommended clearance from a structure is 100′.  (More details on this topic in coming months).
Planting firewise plants in the right place. (see examples above).
Gardeners’ Guild has maintained and planted many of these.

Heat Tolerant Plants
Our micro-climates are changing. Areas that used to stay cool have hot temperatures more frequently.  More people are choosing desert-like gardens.
See photos below for some plants that won’t wilt in the heat.

Heat tolerant plants, left to right: Poppies, Euphorbia and Salvia

Freeze Hardy Plants
This is a partial list of plants that can withstand freezing temperatures.
Correa ‘Ivory Bells’
Verbena Lilacina
Helleborous

Drought Tolerant Landscapes
The drought officially came and went, but it can and will re-occur.
Water bills are rising.
The state of California may reinstate water restrictions making them permanent.
Later this year we will be covering drought tolerant plants and rebates.  Stay tuned.

Multi-Family Housing and its Amenities
It has exploded in the San Francisco Bay Area’s urban areas.  In San Francisco proper, Mission Bay continues to fill in with housing and business.  A breathtaking number of luxury, state of the art buildings have been completed in the last few years.  We highlight trends that are important for Community Managers.

One trend was noted from a recent issue of Bisnow. 
An attractive landscape is a non-negotiable amenity. 
Moreover, it shouldn’t look sparse or overgrown. 
A Multi-Family executive magazine article says that a three-year plan for upgrades that include new fire pits. Or, budgeting for a top of the line grill every few years is a must.

Aside from landscaping, there is a new push for multi-family communities to offer so-called “soft amenities i.e. dog-walking, dry cleaning, packing and concierge services.

A Soil Restoration Brief

David Montgomery, a Geomorphologist and author of books about soil, wants to world to know that organic products’ ability to restore degraded soil has been proven – in his own garden!

Over the years Montgomery had become discouraged that modern agriculture is “stripping the Earth of high quality topsoil.” 

He contends that civilizations throughout history have collapsed due to the depletion of the top three inches of soil.  “The skin of the earth”, Montgomery calls it. While writing a book on the topic, Montgomery’s wife began a project to restore the soil in their backyard.

She massaged in wood chips, fallen leaves, coffee grounds. Also mulch, compost, and a soil inoculant from worm castings. A miraculous transformation took place.  It took several years – but the soil came back.

It’s now flourishing with healthy edibles.  And, Montgomery’s story has become more optimistic.

Story courtesy of Sunset Magazine.

 

 

 

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