To Spray or Not to Spray

I was asked the following question about a situation many new allotment holders find themselves in, clearing an overgrown plot.

I am clearing allotment  that is totally  overgrown  with grass, weeds, docks etc. I have cleaned two sections. Should I treat it with weed killer before I dig it or fork it?

I thought it would be better to fork it first as I could get more root out that way. Also, if dug it I thought I would be cutting up the weed and roots.

Or are there any other suggestions?

I used to work at a large garden and the head gardener used Jeyes Fluid on weeds. Would that be suitable?

There’s an old joke about a lost motorist in the country asking a yokel for directions who replies “You don’t want to be starting from here!” Sorry to say, if I’ve understood you correctly, you’re going at the job in the wrong way and making a lot of work for yourself.

When clearing a plot there are a number of ways ways to tackle it. The traditional, light exclusion, cover and plant and using weedkiller. The traditional methods are sustainable and organic but take some effort. The light exclusion method reduces the workload but takes time. The cover and plant method reduces the workload whilst bringing the land into production quickly, but the method has its problems. Using weedkiller is very effective and takes little effort if you’re happy using the chemicals.

Traditional Digging

Traditionally the plot was dug over with the roots of any perennial weeds like docks removed. The grass and annual weeds were buried in the trench to rot and thereby provide some nutrition for the following crops. The perennial weeds and their roots were composted.

This method is the one promoted in the Dig for Victory campaign.

The Dig for Victory campaign didn’t ignore weeds.

Traditional Digging – Alternative Method

There is an alternative method useful when converting pasture or lawn to a vegetable plot. First, any perennial weeds and their roots are dug out and composted. Using a spade the turf is skimmed off and stacked, grass side down. The plot is then dug over. The stacked turf is covered, usually with a tarpaulin, and left for a year to form a loam.

Perennial Weed Roots

It is important that the perennial weed roots are dug out before cultivation as, given a few weeks, those weeds will regrow from the roots or even a part of a root. The worst thing you can do is to rotavate soil with perennial weed roots as the chopped up bits will mean the plot is covered in new weeds.

Light Exclusion

Covering the land to smother weeds and starve them of light using black plastic was popular some years ago but it’s not as effective as you might think and the land is out of action for a long time. Usually a year. Once the covering is removed it’s surprising how quickly the weeds regrow. And the ground still needs cultivating.

Cover and Plant

This method consists of covering the land with a layer of cardboard and then applying a thick layer of compost (usually 5 to 10 cm deep) to plant in. This does enable the land to be brought into use quickly but it requires a lot of compost which probably needs to be purchased.

Initially it’s great but once the cardboard barrier has decomposed the perennial weeds often burst through to the surface and cause problems.

Clearing with Weedkiller

Using a herbicide to kill the weeds is appealing if you’re happy using chemicals. Many people are concerned that herbicides may be harmful. Personally I think herbicides have their place but keep their use as low as possible. It’s pretty effective method and does save some labour, although not as much as you might think as the land still requires cultivation.

The most appropriate and effective weedkiller for clearing a plot is one based on Glyphosate like Roundup. This is a translocated weedkiller. It’s applied by spraying onto the leaves. They absorb the chemical and transfer it to the roots where it does its business.

The only way the glyphosate gets into the plant is through the leaves. Spray that goes onto the soil basically does nothing when it’s dry. If a weed seed germinates the next day, it will be unaffected.

Time to Work

Often gardeners expect the weedkiller to have an immediate effect. Although the sprayed plant will be dying after being sprayed, it can take a few weeks to be obvious. Ideally after spraying, I think it best to allow a week or two before cultivation to give the herbicide time to get to the plant roots.

Some important points with herbicides. First, read the instructions carefully and follow the safety instructions about protection, hand-washing etc. These chemicals are powerful even if they’re not caustic.

Secondly, don’t be tempted to mix double-strength thinking it will be more effective. It won’t be, it’s a waste of money and may be harmful.

So clearing the weeds and spraying is additional work and expense for no extra return.

Jeyes Fluid

Finally, Jeyes Fluid. Jeyes Fluid is a great cleaning product but really shouldn’t be used as a weedkiller. It most likely will kill the weeds but it will also do a lot of damage to the soil’s biology. It will kill worms, insects and microbes, the life of the soil. Really, don’t use Jeyes as a weedkiller.

Further Information

My book The Essential Allotment Guide has a chapter on clearing a new plot

There are a couple of articles on the site specifically about clearing a plot:

Clearing a New Allotment or Vegetable Plot – This article really covers both taking on a new allotment and converting any piece of ground like an old lawn to a productive vegetable plot.

You Have a New Allotment! – a humorous take on what to do with a new plot but some serious points,