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

 

Subscribe

 
   
   

 

 

 

 

 

Water Graphic-California's New Permanent Water Regulations Explained

California’s New Permanent Water Regulations Explained

We explain California’s new permanent water regulations, in plain language.
Why it was passed. Its effect on you. Below there is a link to resources that will help you conserve.
And, we squish one ridiculous myth flying around the web!

Freshly signed into law by Governor Brown, the bills now make water conservation “a way of life” in California. 
Bills AB 1668 and SB 606 aim to reduce water usage by twenty percent, per capita by December 31, 2020.

Background 

*Climate modeling by Climate Scientist Daniel Swain uncovers another trend – drier autumns with a late onset of the rainy season and a corresponding drier spring.  Source:  published in Nature Climate Change.   

Who is affected?
All California residents.

Why?

A high probability of future extreme drought conditions and the need to plan for them.

It will motivate agencies to repair old and inefficient infrastructure.

What do I need to know?

The state mandates local water agencies to establish water use targets based on their respective region’s climate, land use and population. 

  • Indoor water use limit of 55 gallons per person, per day through January 1, 2025.**
  • Outdoor water usage standards are not developed yet.  (includes landscapes and pools).  DWR will study climate and landscapes around the state to determine guidelines.
  • Commercial, institutional and industrial standards will be defined by 2021.

**East Bay Municipal Water District website, see link below, has information to help you calculate your own water usage.  There’s also a handy table that lists water usage for showers, sinks, washers and other household appliances.

East Bay Municipal Water District Web Page Link

Separating Myth from Fact

Myth

You can’t shower and wash clothes on the same day.

Fact

Not true.

Most washers now use only 9 to, at the most, 26 gallons of water.

An average shower for 8 minutes uses 17 gallons of water. 

Some Perspective

Average per capita = per person.

San Francisco’s average water use is less than 55 gallons per person, per day.

There was a 55-gallon standard set for indoor use set almost 10 years ago.

The 55-gallon limit is more than what is allowed in some countries in Europe.

There are numerous water crises in urban centers all over the world. Water pollution accounts for many of them.  Others, a result of extreme drought.  In all cases, experts say, poor water management is the reason it became a crisis.  Cape Town was expected to run out of water earlier this year, but a last-ditch policy of severe rationing  narrowly avoided a catastrophe.  The city’s doomsday alarm clock was reset for next year.

 

 

 


 

 

 

 

 

 

 

 

This confirms what we expected after a ferocious rainy season that wreaked havoc throughout much the state. 

Key facts:

  • Just one year ago only 5% of the state was drought free
  • Sierra snowpack stands at 179% of its historic average (the biggest in 22 years)
  • San Joaquin Valley and most of Southern California remains in a “moderate drought”.
  • Much of Santa Barbara and Ventura county areas is in severe drought or extreme drought. Although that statistic is down from 2016.

In case you want to know where your water comes a KQED website has an interactive map.  Check it out.

Do you want to know where your water comes from?

Left: Map of 2015
Right: Map of 2017

The list below give you an in depth look at how full our reservoirs are

Reservoir

Status

Serves

Note

San Pablo Creek

130%*

East Bay

Also Briones, Lake Chabot, Lafayette -all full.

San Leandro Creek

127%*

East Bay

 

Lake Mendocino

109%

Northbay

 

Lake Sonoma

100+%

Northbay

 

Marin Reservoirs

100%

MMWD

 

San Andreas Creek

129%*

SF and Peninsula

 

Crystal Springs

127%*

 SF and Peninsula

 

*based on 2017 average percentage capacity

Felicia Marcus, Chair of the State Water Board has expressed relief that water conditions have improved so dramatically, but state policy makers remain cautious.  They voted to continue with mild drought rules and re-evaluate in May.  We will know more about any irrigation regulations by that time.  And, water conservation will likely to be an important issue.

At this time:

Water agencies are still required to report use each month

Wasteful practices such as hosing off pavements and use of hoses without nozzles remain banned.

Sources for this article: San Jose Mercury News, NOAA, KQED.

 

faucet

San Francisco Bay Area – The California Department of Water Resources reminds us that it’s time to turn off your irrigation!

The rains we have had and forecasts for more are sufficient in the short term. Remember that trees, shrubs and flowers use less water in the winter.  One inch of rain is enough moisture to eliminate the need for irrigation in your landscape for at least a few weeks.

On the other hand, we don’t know for sure what the weather gods have in store much beyond this week’s forecasted drenching. Keep an eye out for your plants and water if you notice them looking drought stressed.

Check out the Department of Water Resources for more information.

 

 

droughtmapkeyfinal

Gardeners’ Guild is obsessed with weather.  Well – we are a landscape contracting company and we must adapt on a moment’s notice to rain, high winds and unseasonable heat or frost.  We also stay on top of long term forecasting because our clients depend on us to help them manage their resources.

I personally am obsessed with it. One, I need to since our San Francisco Bay Area readers are.  And two, I find it fascinating. 

Our recent heavy rain seems to suggest a wet winter.  Yes! More is predicted this weekend.  Will our reservoirs be full by next spring?  An article in the San Jose Mercury News and the most recent post on weatherwest.com has some indications based on weather forecast modeling.

We are still officially in a drought, however.  If you look at the map above you can see why.

However, there are parts of the Bay Area that have been downgraded to just “abnormally dry”.  These counties are Sonoma, Marin, San Francisco, San Mateo and Santa Cruz, Western Napa and Western Santa Clara. Unfortunately, Santa Clara County, as well as Contra Costa, Alameda, Solano, San Benito and Monterey remain officially in a drought. 

Water experts say that it would take a “very wet winter – all across the state – or perhaps two wet years – to end the drought statewide.

Forecasting from weatherwest.com post on October 25th described conflicting information that obscures any long term rainy season forecast. In his article, Daniel Swain says that climate modeling suggests a few possibilities:

  • Another Pacific high pressure ridge again
  • A warm winter
  • A possibility that Northern California’s will enjoy more precipitation than Southern California

Swain, in his last post, suggested that a La Niña was less likely. But his October article says we are “edging back to a La Niña-like” event. His evidence is cool water in the eastern Pacific and a warming trend for the tropical West Pacific.  This, he says is linked to an unusually high pressure system.

I wish could pass on better news.  And, of course we don’t know for sure.  That’s kind of frustrating. So continue rain dances, visualizing and we will continue offering advice on water conservation and irrigation that saves water.

The California drought map shown above represents the state as of November 10th. (2016). 

Some additional facts about the rain in October:
The October drenching was the wettest since 1921
San Francisco ‘s rainfall was 209% of average
But, the soil was dry and therefore the rain did not increase water levels as much as you would think. 

Sources:
Weatherwest.com
San Jose Mercury News