Tag Archives: Herbicide

Weed control


In My 30 years  of  horticulture  I have  learnt that  there  are  several ways  to  control   weeds.    I said control because there is no way of  eliminating them.          You may think that by  putting a  mulch  down  will  solve  the  problem, I tell  all  My  clients  that the  mulch  will  only  stop  weeds  breaking  through  the  soil  if  the  layer  is  an  inch  thick  but that  wont  stop seeds that’s either   dropped  by  birds and  wind  settling  on  top  of  your  mulch .And  germinating

Not  longer  ago when  I  was  working for  Lambeth, We  used  to apply  a  weed  killer  called  Casron G. This  was  a  residual  weed  killer  that  stopped weed germinating ( a pre emergence ) in  there  tracks  but  unfortunately due  to  health  and  safety  this is  no  available  along with  it  Domestic  Counter part  Cover shield.

However there  is a  professional product  on  the  market  called  Kerb  which  does  the  samething  but  has  a  different  chemical.But  unfortunately  it  only  sold  to  professionals  and  not  to  the  general  public.

So I’m  going  to  take  you  through  the  ways  of  tackling  weeds .

Cultural  Method


When  hoeing  I’ll prefer  the  use  of  the  a  good  dutch  hoe  that  can  slice  through  the  weeds  with  ease.                                                                                                          Yes I  said  slicing  what  you  want  to  do  is  cut  bellow  the crown and  chop  off  any  vegetation.This  will  make  take  away  all  the  nutriment  from  the  plant  and  after several  retries (if you  keep on  top  of  it  the  roots  will  swivel  up  and  die  ) .Make  sure  that  if  you  hoed  up  the  young  seedlings  to  clear  the  surface  as  they   might  be  able  to  re-root  again.

when  hoeing  make  sure  that  its  in  dry  hot  weather  as  this  can  dry  up  any  roots  that  are  left  on  top  of  the  soil and  prevent  them  from re-rooting.

Propane  weed  gun 

weed  gun

Using a propane weed killer on a bed

This does  the  same  thing  as  hoeing  ie   removing  or  burning  the  foliage,which  is  then  brushed  away  and  disposed  of.


  • The  flame  can  reach  onto  the  weeds  with  out doing  permanent  damage to  the  barks  stem.
  • the  lighter  version available  make  it  easier  to  carry  and  direct  the  flame.


  • even  if  you  choose  the  lighter   version  of  it   the  propane  cylinder  might  not  last  long
  • it  is  not  all  that  cost  effective
  • storage  if  you   choose  to  buy  the  bigger  version   then  you  got  the  problem  of  storage
  • health  and  safety  rules  should  be  applied  as  these  canister  are  like  ticking  time  bombs  if  they  aren’t  stored  right
  • they  can  be  very  heavy  to  use  esp  the  bigger  ones   and  will  need  to  moved around  on  a  troley

Hand  weeding


  • The  finished  look  can  be  very  appeasing
  • Its  cheap  cause  there  no  equipment   to  be  used


  • when  you  pull  out  the  root   you  are  more  than  likely  to  leave  the  tap  roots  in  the  soil  to  re-root  again  although  the  vegetation has  been  removed  esp  with  the  cases  of  the  dandelions   and  burdocks   roots
  • it  can  be  time  consuming  and  laborious  esp  if  you  have  a  large  area to  cover
  • some  weeds  are  impossible  to  remove  esp.  if  there  are  in the  patio  and  growing  in  concrete  are  tarmac


For  a  mulch  to  be  effective  it  most  be at  least  1″  thick   and  not  leave  any  gaps where the  weds  can  grow  through .

The best  way  to  apply  a  mulch  is  to :-

  • weed  and  clear  the  site  first
  • water  the  surrounding  area  well  before applying
  • leave  a  small  gap  around  the    stem  of  the  plant   so  you  can  water it
  • DO NOT  USE  fresh  matter  ie  manure  or  wood  chipping   as  the  manure  will  rot  the  roots  of  the  plant   and  wood  chipping  have  toxins  that  kill  any  young  growth


  • If  you  got  a   site  right  at  the  bottom  of  the  garden that  you  don’t  look  at  or  allotment  site  which  needs  to  cleared   one   cheap  way  is  to  use  a  old  rug  or  carpet will  do
  • convert  it  upside  this  will  suppress  any  weeds  from    growing  up  cause  they  can’t  get  any  light  and  these  will  eventually  die
  •   an  black  membrane  is  ideal  as  temporary  mulch    esp  when  laying  a  slabs  or  turfs  in  a  small  garden .  The  sheets  are  made  to  allow  water  to  go  through  the  soil  and  stop    plants  from  growing
  • Also  You  can  use  it on   small  beds  by  covering    the  sheets  with  fresh new  soil
  • Manures  (well  rotten)
  • Compost –  tip  make  sure  the  peat  based  compost  is  well  wet. This will  bind  the  particles  together   and  act  like  a  thick  sheet
  • straw
  • decomposed  bark
  • stones with  Sheets or  carpets
  • basically  anything   that  can  block  out  the  light

But  as  I  mentioned  before    this  doesn’t stop  other  weed  growing  esp.  in  the  case  of   manures  and  compost  where  weed  seeds   are  dropped  by  birds and  wind

Chemical  Method

As  a  professional  gardener  I am  often  asked  to  weed   patio  and  drives   & like  I  said  before  weeding  by  hand  can  be  laborious. Therefore  I  would  apply  a  chemical  weedkiller  to  do  job  very  effectively   and  quickly.

However  with  the  growing  concern  for  the  environment  I’m  looking  into   other  ways  to  control  weeds using  the organic   approach

There  are  three  different  types  of  chemical  weed  killer  on  the  market  at  the present  and  its  important  to  know  what  to  choose  for  a  particular  job

  • A  contact  herbicide  like  diquat   where  the  plant  tissue  is   burnt  to  a  crisp  or  frazzled  up  is  ideal  for  annual  weeds  as  per annual weeds   have a  long  tap  root  that  needs  to   killed

However   a  constant  application  of  the  chemical  should  slow  the  plant  down  until it  dies  away .

  • Systemic:

    Systemic or translocated weedkillers are absorbed by

    plants and carried around the whole plant, including the roots.

    They are suitable for the control of both annual and perennial

    weeds but they do rely upon weeds being in active growth. They

    will thus be less effective and slow-acting if they are applied in

    periods of slow growth such as cold or drought.


Resolva weed killer

  • Selective:
    Some weedkillers contain active ingredients which will selectively control weeds with a certain type of growth habit without harming plants with a different growth habit. Lawn weedkillers will selectively control broad leaved weeds without damaging the grass. Selective weedkillers may be either contact or systemic in their mode of action. Most weedkillers currently available are non-selective – ie they will cause damage to cultivated plants, as well as weeds, so care must be taken when the weed killers are being applied.
  • Non residual These  weedkiller  are  ideal  if  you  intend  to  plant  in  the  same  spot as  the  chemical  leaves  permanent  traces  in the  soil these  are  often  known as  biodegradable

professional granule herbicide

  • Residual
    A residual weed killer remains active in the soil for several months or longer, depending on the product and climatic factors. While it continues to be active weed growth is prevented. Most residual weedkillers are used primarily in Combination Products (see later) for long term total weed control. These products should not be used near established plants or if the treated area is required for planting purposes in the short to medium term (check product label).
    There are residual weedkillers which can be used prior to planting and/or around gr
    owing plants. They are generally suitable for use around shrubs and woody plants and can be very useful for customers wishing to have a low maintenance garden or area, provided they are happy to grow only woody plants such as shrubs or roses.
    Combination Products:
    Several active ingredients with different modes of action are formulated together into one product.
    For instance a contact acting ingredient will control existing growth while a residual ingredient in the same product kills any germinating seedlings for several months. Examples are the path weedkillers
path  clear

path clear

Non organic

My  choice  and  many  others  is  mix   of  diquat  and  glyphoshate   weed  killer     d1quat  when  applied  as  single  solution  acts  like  the  propane   weed  killer  above  and  burns  the  leaves  to  a  crisp  whilst  glyphoshate  works  by  being  aborbed  through  the  leaves  and  then  killing  the  roots  making  sure  that  there  is  no  chance  of  the  weed  coming  back .

Although  it  takes  time  for  it  to  take  effect  there  is  some  serious  draw backs  in some  cases  lately it  has  been  reported  that  glyphosate  no  longer  kills  broad  leaf  weed .  whether  this  is  true  or  not  is  hard  to  say  as  i  havent  seen  anything  yet  that  tell  me  otherwise.

But What  I  do  know  is  that  after  several  yrs  or  months  the  weeds  are  back  on  the  drive .  So  that  why  Im  on  the  look  out  for  a  more  effective  way  of  controlling  weeds

However  if  you  still  wont  the   chemical  approach    here  are  list  of several   that have  the  mixture  mixed  up  all ready  for  you

  • 24hr weedaway
  • Resolva  products   path  and  patio  concentrate

Organic  weed  killers

Home brew  (not  yet  tested )

On My  research  for  a  better  weedkiller I  have  come  across  some  very  strange  remedies  :-

  1. Vinegar

Vinegar  is suppose to  burn  the  leaves  like  d1quat and  the  torch depleting  the  plant  of  its  sugar  to  promote  growth.

As I  said before  I  haven’t  yet  tried  this  out  So  I  can’t  really  give  judgement  on  it  but  what  I  gathered  from  the  forums that  it  only  draw  back is  that  it  has  to  be applied  during  hot  weather to  be  effective.

My  main  concern as  with  all  other  chemicals  man made  or  organic   is  what  effect  it has  the  soil .though  acetic acid  is  manufactured  ny  some  weed  killer  firms


Acetic acid herbicide

Although  the  instructions  claim  say  it  safe  i would  advise  all  the  safety  precautions  i  mentioned  in  my  blog  about  chemical  management  be  used  as  clearly  the  MSDS  document  on  acetic  acid  says  it  not                        Acetic acid  MSDS

Boiled water

This has  the  same  effect  as  above  if  you  ever  suffered  scalding  hot  water   on  your  skin  you  can  imagine  what  effect  it  will  have  on the  weeds. So  it  just  might work.

My  only  worry  is  :-

  1. Health  and  safety  of  it  you  have  to  extra  careful  not  spill  any  of  it  your  self  and  also  carrying  it  out  to  the  path  or  patio
  2. some  suggest  using  left  over  vegetable  water –  my  only  problem  with  that  is  that  salinity  of  it  might  too  much  for  the  soil  and  then  nothing  will  grow  cause  of  the  increase  of  salt  level .                And  then  there  the  run  off  into  our  drains .Although  most  of  the  waste  from  the  sink  goes  the  same  route


From  My  experience  and  knowledge    salt  kills  everything  by  osmosis  ie  the  concentartion  of  minerals  draws  the  less  minerals  from  the  plant  like  a  sponge thus killing  the  plant  with in  days.

This you  to   might  be  ideal  cause  its  safe  to  use  cheap  but  by  overdosing   every  time  you  see  a  weed  is  only  increasing  the salinity  in  the  soil  and  then  nothing  will  live  there  and  the  earth  will  become  sterile


For  best  results  it  best  to  water  the  weeds  first   in  dry  hot  weather  as  this  will  make  the  plants  more  acceptable  to  weed  killer

systemic weed killers based on glyphosate need between 4-6 hours without rainfall in order to be absorbed properly by weeds. If it rains in the interim, it may be necessary to give a further application. It is also a good idea to know what to expect in terms of weed control – systemic weed killers take longer to show the effects of control than contact weed killers and users often don’t realise this, so they may think the weedkiller isn’t workin


Chemical Management

English: A sign warning about pesticide exposure.

English: A sign warning about pesticide exposure. (Photo credit: Wikipedia)

An Health and  Saftey  Warning

User habits surveys for 2007 and 2010 indicate that gardeners don’t always use, store and dispose of pesticides correctly. If you use pesticides, you are responsible for using these chemicals correctly and effectively. We must keep our gardens and allotments safe for children, pets and wildlife.


When I  was  working  for  Lambeth Council  back  in 1980  all  the  employers  had  to  pass  a  strict  pesticide course  lasting  a  year  this  was  a  tough  course    but  it  made  you  aware  of  the  dangers  of  the  product  and  how  to  safety  apply  it.

But  looking  on  the  prospective  of  the  member  of  the  public  these  rules  no  longer  apply  as most  products  you  buy  claim  to  safe  to  the  environment if  you  follow  the  instructions  to  letter

But  with  this  scare  of  slugs  pellets  and  weed  killer  getting  into  our  water  I  don’t  think  the  news  is  getting  across

So  I’ll tell  you  how  to  apply  herbicides  or  pesticides  safely

  • Read  the  Label  (  I  know  it  obvious  &  that  you  think  you  know  it  all  but  you  don’t)  How  many  of  you  put  weed killer  down   then double  dose  the  plant  again . This  is  all  wrong  the  formulation  is  worked  out  in  the  lab.  for  maximum  effect  and    by  double  dosing  you  are  probably  increasing  the  salinity  of  the  soil.
    description of  pesticide  label

    description of pesticide label


  • Calibrate  –  What  I  do if  using  a  sprayer is to  fill  up  the  water  with  water  and  go  over  the  plant   or   ground  first   making  sure  that  plant  is  soaked  ie  beginning dripping  or  that  ground   is  covered  with  spray .

I  then  see  how  much  water  i  used  and  then  do  a  simple  division  to  find  out  how  much  chemical  i  actually  use  use all  the  instructions  say  4 cap  full  to   1 litre  or  1  gallon  of  water

  • When  using  any  chemical  always  use  PVC  gloves   these  are  cheap  and  better  than  latex  gloves  that  can  rip  and  allow   the  chemical  to  get  in  touch  with  your  skin
Red  Pvc  gloves

Red Pvc gloves

Note  the  tight  cuffs  around  the  wrist  this  makes  sure  that  nn  drips  get  on  to  your  hands

  • When    mixing  the  chemical  put  in  the   some  water  first    then  add your  chemical ( Some  products  have  it  all  ready  made  up  if  so  skip this  )  and  keep  on  stirring  it  until  it  dissolves then  top  up with  the  rest  of  water  mixing  it  again .By  doing  this   you  have dissolved  and  mixed  up  all  the  chemicals
  • If  the there  a  slight  breeze  or  wind  blowing  either  wear  a  mask  or  try  not  to  spray  into  the  wind .(  Note  chemical  spray  can  carry  in  the  wind  for  miles  without  you  knowing  and  with  out  a  mask  you  likely  to  get  some  on  your  mouth   )
  • Although  there  are  organic  or  biodegradable products  that  claim there  are  safe  I  always  veer on  the  side  of  caution

How  to  calibrate  your  sprayer 

The single most asked question in pesticide application is: “How much do I put in a knapsack?”

The answer is that it depends on the calibration of your sprayer. In short, how many square metres one sprayer full of water + pesticide will cover.

It is important that the correct amount of pesticide is applied per square metre, the amount of water much less so.

An  Professional Knapsack sprayer

An Professional Knapsack sprayer

As every sprayer has a different capacity, different nozzles with higher or lower output, a different operator who works at a different speed and pumps at a higher or lower pressure, calibration is the only answer. Here is one simple way to do it:

1. Measure exactly one litre of water into an empty sprayer and prepare it for spraying.

2. On a dry hard surface where you can see the spray wet it, walk forward, continually spraying as you would normally operate until the sprayer is empty. Measure how many square metres you have covered. Let us assume that this might be for instance, 20 square metres.

3. If your sprayer is a 15 litre model you multiply its normal capacity (15) x 20 (area one litre covered) = 300 square metres. This is the area that a whole knapsack will treat.

4. To work out how much pesticide to measure into the sprayer is now very easy. Look at the application rate on the product label.

eg. Roundup ProBiactive is 5L (=5,000ml) per Hectare (10,000 sq. metres)

5. To calculate how much to measure into your sprayer:

For example: 300 (Area that one sprayer full will cover) x 5,000 (Pesticide application rate per hectare in millilitres) / 10,000 (One hectare in square metres) = 150 millilitres

amateur sprayer

Start  your  spraying

  1. Working  up  and  down  the  plant   making  sure  that  both  surfaces  of  the  leaves  are  well  coated  and  started  to  drip
  • Always  spray  first  thing  in  the  morning  this  is done for several reasons ;-
  •   to  avoid  any  harm  to  the  pollinating  insects
  • and  also  the  leaves    spores  will  be  fully  opened
  • The  plant  has  time  to  recover   after  the  spray    and  the  leaves  will  be  dry
  1. Avoid  spraying  any  chemicals  near  water

For  Weed  Killer   there  is  one  simple  rule  DO NOT  SPRAY  NEAR  WATER  SURFACES

If  you  miscalculated  and  still  have  some  chemical  left  NEVER  EMPTY  IT  DOWN  THE  DRAIN

Storing  Chemicals 

  • After you have used a pesticide, make sure that the packaging is tightly closed or sealed to avoid spillage.
  • Store pesticides in a safe place, out of reach of children and pets.
  • Take particular care to store slug pellets safely to avoid accidental poisoning of children and pets – particularly dogs.
  • Garden sheds and greenhouses are not ideal for storing pesticides as they can get very hot in summer or cold in winter. Pesticide products are best stored at an even temperature.
  • If you store it carefully, any remaining pesticide will be effective for some years to come. You can check whether it is still legal to use by using  there  database

Concentrated pesticides that have been diluted and stored may not work as well when you next use them. It is also illegal to store pesticides that are unlabelled and not in their original container for safety reasons. Remember to only dilute enough for that day’s use.

Disposing  of  Chemicals

  • Whether you’ve diluted it or not, never pour pesticides down a drain or any other water drainage system (e.g. sink or toilet) because of the risk of contaminating water and harming wildlife. You could face prosecution.
  • Pesticide containers that have held concentrated product (i.e. requiring dilution before use) should be rinsed three times adding the washings to the final spray solution. The empty container can then be placed in household waste.
  • Empty pesticide containers that have held Ready-to-Use product (i.e. trigger sprays) can be disposed of directly into your household waste.
  • Other empty pesticide containers e.g. bags and cardboard boxes can also be disposed of in your household waste.
  • Check the label for any other advice on disposal of the product or empty container.