MANAGING WEEDS IN THE GARDEN

 

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Weeds, as we call them, can be one of the most frustrating challenges for the gardener. They often seem to grow faster than our cropping plants, and it can feel like and endless battle to keep them under control. 

Weeds are not entirely bad all of the time. They protect the soil from the drying forces of sun and wind, and accumulate nutrients which we can ultimately return to the soil. Some weeds, such as clover, also fix nitrogen into the soil from the air, since they are a legume. 

The key to managing weeds successfully, is to develop a smart strategy and to work with nature instead of against it. Using the tips on this page you will surely have your garden weed population well managed in no time! 

KEY PRINCIPLES

There are some general rules to follow straight off the bat that will drastically improve the weeds situation in your garden over time. We'll cover some more specific methods of weed control further down the page but some key principles for weed management include: 

  • Prevent them from going to seed. Even if you don't have time to thoroughly weed your garden, doing a quick circuit around your property a couple of times a week and pulling out any weeds that are flowering or about to go to seed, or at least lopping the tops off them, will have great long term benefits. A single weed plant left to seed can produce hundreds, or even thousands of seeds, some of which can lay dormant in the soil for years just waiting to sprout at the right moment. 

  • Prioritise your most problematic weeds and target those first. For example, some weeds in my garden are relatively benign, like clover and chickweed. They don't cause big problems in the garden. Other weeds, like dock, thistles or dandelion can become well established and difficult to remove after a while. And if they go to seed then you're looking at a big weed invasion. Target your problem weeds as a priority. This also includes if you notice a new kind of weed that is just starting to get established in your garden. You can nip it in the bud before it takes over. 

  • Learn what the weeds are telling you. Often times, a proliferation of a certain kind of weed can be an indication of a soil deficiency or imbalance. For example, buttercup thrive in acidic soils, and an application of lime can often tip the balance in favour of your food crops. 

  • Turn your weeds into a resource. Many weeds, especially ones with deep tap roots, are capable of drawing minerals and micronutrients up from deeper soil layers than what many vegetables manage to reach. These plants and their leaves, especially if they have not been left to go to seed, are a fantastic resource for your soil. Often times when I am pulling unseeded weeds, I simply leave them laying on top of the soil right where I picked them. They die from baking in the sun and become a ready made mulch layer. They're also an awesome ingredient in the compost heap or worm farm. 

  • Foster edible weeds. I have a section of my garden that is quite 'wild'. To the untrained eye it looks like its full of weeds. But if you take a closer look, almost everything that is growing is edible or medicinal. I spent a few years pulling out the weeds that I had no use for and letting other desired crops, like parsley, rocket, oregano and chamomile go to seed. Over time, this selection process has now meant that the 'weeds' aren't even weeds! Not to mention, many of the plants that we usually call 'weeds' often have edible or medicinal uses themselves. 

MULCHING AND NO-DIG GARDENING

Using mulch, and minimising tillage of your soil, has many benefits, including weed management. Many weed seeds are able to lay dormant in the soil for several years, germinating when they are brought close to the surface and get warmth, moisture, air exchange and light. By minimising tillage, you minimise the number of weed seeds pulled up into the germination zone as well. 

Another great thing about adding mulch layers, is it smothers and suppresses any weeds that are already growing. In addition to this, a garden which has been regularly mulched has such loose, friable soil that any weeds that do emerge are incredibly easy to pull out. 

Mulches can be any kind of organic matter that is easy to spread on your soil, which you can place around your cropping plants, or when you go to plant them, make a hole in the mulch layer and plant them into the soil.

 

The mulches I most commonly use include: 

  • Pea Straw

  • Autumn leaves (avoid walnut, maple, pine and eucalypt as they contain growth inhibitors) 

  • Finished compost

  • Grass clippings

  • Sawdust or chipper mulch

  • Sea grass or seaweeds

As mulches break down, the bacterial activity can increase acidity. A light sprinkling of lime on top of a mulch layer helps it break down to a neutral pH. About one small handful per square meter of garden lime. 

Growing cover crops / green manures is another fantastic way of making a 'living mulch' which can very effectively smother and decimate a weedy patch simply by smothering them out over the course of a few months while it grows. 

 

HOES AND OTHER WEEDING TOOLS

Over the few thousand years that humans have been cultivating plant crops, we've developed some pretty simple yet effective tools that can make short work of a weeding job that would be time consuming if done by hand. 

Everyone has their own preference for what kind of weeding tools they like to use, and it also depends on the specific circumstance, for example the crop spacing, the type and density of weeds, and the structure of the underlying soil. 

Tools ranging from a basic 'wonder weeder' (essentially a bent hook of #8 wire with a handle) to a well sharpened torpedo hoe with a long handle can be great assets in clearing a garden patch of weeds. Another useful tool is a hand weeder with a small two-pronged fork at the tip and a bend in the shaft for leverage. This allows you to poke it deep into the soil, grasp the root of a deep rooted weed (like dock, thistle, dandelion) and then leverage the plant out root and all. 

I would highly recommend visiting your local gardening centre or second hand store and having a look at different weeding and cultivating tools and try them out in your own garden. 

 

SOLARISING

Solarising is the practice of using sheets of clear or black polythene to 'cook' and smother weeds using the suns energy. It is a great way to kill off weeds without the use of herbicides or hard manual labour.  

While we encourage the minimisation of the use of plastic as much as possible in gardening, solarisation is and extremely effective and easy way to kill off weeds in a certain area. If you buy a high quality piece of polythene to start with (and preferably with UV protection), a single piece can be used time and time again for many years. 

The process of solarising is very simple. We recommend using black plastic in the cooler seasons (as it absorbs more heat), or clear plastic if you are solarising in the height of summer, although either black or clear will work at any time of year if needed. The process is as follows: 

  1. Mow or weed whack the area you want to solarise. This is not an essential step but it aids in the process, by letting the plastic sheet form a better and more even seal / coverage and also gets the composting process kick started by laying a mulch layer down on the area. 

  2. Get the area as level as possible if it has lumps and bumps. Use a grubber or spade to take the tops off bumps and fill hollow bits.

  3. Water the area thoroughly. Having moisture trapped under the sheet will speed up the process of decomposition and fungal / microbial activity under the sheet. 

  4. Lay the polythene sheet over the desired area and secure it. You can buy specially made 'weed mat staples' from garden centres, which are like a double pronged tent peg. You can also make your own with sturdy wire, or use sones, logs, bricks etc to hold the sheet down. Whichever method you choose, make sure the sheet is firmly anchored to the ground and will withstand high winds without coming loose. 

  5. Leave the sheet in place for a minimum of 4 weeks. The longer you leave it there the more of the weeds (and soil borne weed seeds) will die. 

  6. If you want to supplement your soil in some way, after a couple of weeks of solarisation you can lift the sheet and add organic matter such as seaweed, manure, pea straw, leaves etc. to help build your soil. If you do this, sprinkle a handful of garden lime per square meter onto the material and then water the patch thoroughly again before replacing and re-securing the polythene. 

  7. After several weeks of solarisation your patch will be ready to remove the polythene and begin gardening! 

FLAME WEEDING

Flame weeding is another chemical-free method of weed management employed by organic gardeners around the world. 

The process is simple. A blowtorch type device is used to briefly skim across the ground, rapidly wilting any young and emerging weeds. 

Flame weeding is most effective on small and young weeds. Larger weeds like well established dock, thistle and so-on will not get killed by it as their tap root will easily survive the flaming process. 

Flame weeding is most often used after preparing a fresh plot ready for planting. If you prepare the bed, water it and wait a week or two, the main 'flush' of weed seedlings will emerge and can be easily killed off with flame. The bed is then ready to sow with seed or seedlings and if you keep soil disturbance to a minimum when planting, you will have prevented the bulk of the weeds that would cause headaches later on. 

For direct-sown crops such as carrots, beetroot etc, people will often sow their seeds, and then flame weed a few days later. The seeds you sowed will not have emerged above the soil yet, and therefore protected from the flame weeding process, but emerging weed seedlings will be killed. This gives your soon-to-germinate seedlings a great head start not having to compete with so many weeds in their first couple of weeks of life. 

Many people have a tendency to overdo the intensity of flame weeding. The general method is to pass the torch across the ground in a slow sweeping motion. You are not aiming to completley cook / fry / obliterate the weeds. As you pass the flame across the weeds there will be a very obvious moment when the leaves wilt or droop. That's the job done. They will still look green straight after, but if you come back for a look a day or two later you will find that they are dead. 

Specially made flame weeders for home gardeners are available to buy at most garden centres. Or there are more advanced versions available to buy online if you are operating at a larger scale. At a very small scale, a standard hand held welders blowtorch can do the trick just fine. 

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