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Weeds

What is a weed?

Technically a weed is just a plant in the wrong place.

It may be an unwanted seedling from another plant, or a plant that is quick to colonise, but difficult to eradicate.

You will never be able to completely stop weeds from popping up, but there are ways to ensure that they have less places to grow.

For instance, bare patches of soil can be quickly colonised by weeds,so keeping these types of areas to a minimum by using ground covering plants is a simple preventive measure.

Alternativly, cover these areas with a mulch, or as a temporary measure, cover with a plastic weed suppressing membrane which can be removed as and when the area under it is required.

There is a saying that one years seeds is seven years weeds,there could be an element of truth in this in so far as:

Annual weed seeds can survive for years in the soil, waiting for the perfect conditions to grow, then once germinated they can grow and set seed very quickly giving the effect of continuity.

Small clumps/patches of these weeds can generally be dug out before they become a nuisance, but when large clumps have been allowed to form it may not be so easy to eradicate these.

If digging them out fails then chemical control is often the most efficient way to remove them.

That is, there may be a need to use herbicides!

The potential problem here is, herbicides can also damage other garden plants so they are best avoided unless absolutely necessary.

The first approach should always be to remove annual weeds from the soil by hand or with a hoe.

Do this by severing the tops from the roots, before they have a chance to produce seed and spread.

Perennial weeds can be removed with a hand fork.

It is important to remove all perennial roots, as some can regrow from any bits left behind.

In footpaths one may have to use an old knife or similar to scrape weeds out of the gaps between paving slabs.

One could also consider using a flame gun on large paved areas.

Weeds can sometimes be a problem in containers and planters, these should be pulled out by hand.

Removing the top couple of inches of soil and replacing it with new will possible remove any resting unwanted seeds and help to nourish the remaining plants.

Placing a decorative layer of coloured gravel or slate over the new soil will help to prevent weeds returning.

Herbicides:

Weed killers should be a last resort, and only used where control by cultural methods have failed.

There are basically three types of weed killer / herbicide:

Contact: these kills any plant tissue it touches.

Systemic; is a type that is taken in by the plant and is spread down into the roots which eventually kill the plants off.

Residual: is a non-selective type, it kills all forms of plant life, and will often persists in the soil for up to six to eight weeks after application.

The most effective types of herbicides are based on either glyphosate, or ammonium sulphamate.

Always check manufacturer's recommendations for individual herbicide properties and methods of application.

Further Information:

Always read the instructions on the packaging, adherence to these instructions is a legal requirement.

Do not buy more than you need as many weed killers have short shelf lives.

For small applications use ready-to-use packs.

Wear protective clothing, in particular, gloves, mask and goggles.

Where possible use a pump sprayer as opposed to a watering can, this is both more accurate and more economical.

Keep a dedicated sprayer/watering can for use with weed killers to reduce the risk of contaminating cultivated plants.

Apply weed killer using a spray heavy enough not to drift, but fine enough to cover foliage evenly.

Do not spray on windy days.

Weed types:

Bindweed:

This twining fast-growing climber is a difficult weed to eradicate by cultural methods as its roots can extend up to 5m or more.

Persistent digging and hoeing can eradicate bindweed in a couple of years.

Glyphosate based weed killers are effective when the weed has reached the flowering stage.

Earlier spring applications are generally less successful.

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Chickweed:

Is an annual weed that continues to grow throughout the winter months.

In smaller areas hand removal is best as hoeing can cause it to transplant, otherwise use a glyphosate based weed killer.

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Couch grass:

This vigorous, perennial grass spreads rapidly by rhizomes (underground stems).

If any part of these rhizomes are left in after weeding these will also regenerate, so total clearance is the best course of action.

Refrain from using a rotovator if there is any of this weed about as all it will do is cut the rhizome into small pieces, and make matters worse.

In lawns or grassed areas are affected close mowing may eliminate it.

Glyphosate based weed killers can be effective on young shoots, so a spring application can often be quite successful.

With heavy infestations digging out may be the best course of action.

If the ground is not required for at least six months some of the residual type weed killers may be effective.

Black plastic sheeting and landscape fabrics can help to suppress the weeds.

After removing the covers an application of a glyphosate weed killer may be required.

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Ground Elder:

Another invasive weed that that spreads by rhizomes, and requires similar treatment to couch grass.

Glyphosate weed killers are fairly effective but several applications may be necessary.

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Japanese knotweed:

Japanese knotweed is a notifiable weed which can only be disposed of in licensed landfill sites or burned on site.

It was originally planted as an ornamental plant but now is one of the UK's most invasive weeds.

Digging out the roots will deal with small scale infestations.

Repeated applications of glyphosate weed killer when the weed is 600-1200mm (2'-4') high can sometimes be effective.

Covering small, young clumps with landscape fabric may also provide control.

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Field horsetail or Mares tail:

This weed has been around since prehistoric times.

It is a deep-rooted, creeping weed that is difficult to get rid of.

Continued hoeing and pulling out can weaken it, as will repeated applications of glufosinate ammonium or glyphosate based weed killers.

Lawn weed killers and mowing can suppress it in lawns, and path weed killers can be effective on paved areas.

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Weeds such as stinging nettles and creeping thistles are perennial weeds that are best dug out completely to prevent spreading.

 

Stinging Nettles

 

Creeping Thistle

 

Creeping Thistle


Always check manufacturer's recommendations for individual herbicide properties, and methods of application.





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