As mentioned at the start of Part A of ‘Prevention is better than cure’ Weeds make their way into our landscapes three ways –
- Weed seeds or runners are imported in things we buy for our garden,
- Weed seeds are brought onto the property by natural forces such as wind, water or transport by animals or ourselves (think cobblers’ pegs in your dog’s coat or your socks!), or
- They are pre-existing.
Cobbler's Pegs (bidens pilosa) gotta love 'em!
While the previous article dealt with strategies to prevent (1) bringing weed species into your garden, this one will deal with strategies to prevent problems with (2) weed seeds brought onto the property by other agencies such as wind, water etc. or (3) weed seeds already existing in your soil. The following strategies will impact weed seeds arriving and weed seeds already existing in your soil.
Strategies
1. Avoid cultivation – This means not turning the soil over unless it is absolutely necessary, because this may stimulate existing or blown in weed seeds into germinating. There are times when some tillage is inevitable, like if you want include soil amendments like garden lime if your soil pH is a bit low or add fertiliser’s like chook manure.
We use the chook tractor and the chooks will turn the soil over a bit, but will also consume any weed seeds that they find. Occasionally, if we have had wet weather, the chooks can cause some surface compaction of the soil, so I need to go through with a small hoe once the tractor has moved on, and break the surface up a bit before I apply the mulch. Which brings us to our second strategy –
2. Mulch – Think of bare earth as an open wound. If you have been working on your garden and left the soil uncovered, like a bare wound, nature will begin the healing process for you by germinating all those dormant weed seeds present in the soil. If you don’t want that then the idea will be to mulch the bare area as soon as possible, with whatever material you have to hand. Even rocks can be used as an inorganic mulch.
We use straw that has been worked over by the chooks in the retirement village, because they break it down a bit, add manure and clean up any residual wheat seeds. The wheat straw goes on our annual vegetable beds and we use wood chip mulch around our trees, shrubs and other perennials. If you know you are going to be doing some gardening work that will expose the soil, having some material which can be used as mulch ready to go will mean the open wound gets a proper dressing as soon as possible.
3. Water – Apart from the fact that it is wasteful and inefficient, watering indiscriminately by hose or sprinkler allows all those dormant weed seeds to come busting thought and give you a hard time. The secret is to put the water where it is needed directly – underground near your crops’ roots. While we have tried a number of ways to do this over the years, I have found that I keep coming back to two techniques – ollas for our annual veg and deep pipe waters for our perennials.
Deep pipe waterer for perennials
Ollas are unglazed terracotta pots buried up to the neck in soil in our veggie beds. They can be made from scratch if you are a potter, or made from commercial pots if you are not. They allow water placed inside them to seep out slowly in the root zone of the vegetables. Deep pipe waterers are 50mm PVC tubes, 500mm long with holes down the side, buried upright within the drip zone of perennial plants, again, allowing water to be delivered directly to the plant roots without wasting any water germinating weeds on the soil surface. For more details on both of these irrigation methods check out the links at the end of this article.
Ollas from pots
Of course, we can’t control the rain, but in drier seasons watering using ollas and deep pipe waterers can reduce the water you need to irrigate and weeds germinating where you don’t want them.
4. Encourage predation of weed seeds – ants of the species Rhytidoponera and Melophorous eat weed seeds and are found widely around Australia. Crickets and ground beetles (specifically Carabid beetles) also consume weed seeds. Clearly this is a behaviour which we should encourage.
Actions to encourage the presence and activities of these insects generally includes: Not using broad spectrum insecticides in your garden and not digging your garden over (see 1. Above). Leaving leaf litter undisturbed and providing a log pile and low growing plants as habitat for ground beetles and crickets is also a good idea.
Bird manure - great for fertility, but not so much when it is on the lettuce, or growing weed seeds
5. Check under bird roosts – Birds are great ‘concentrators of fertility’ or in other words, they eat elsewhere, then come and crap their extremely fertile manure on your place. This is a good thing and should be encouraged. However, there are some weeds which have evolved seeds that survive the digestive tract of the bird and use birds to extend their range. Such weeds include Privet, Ochna and Asparagus Fern around here and perhaps others or different ones depending on your location. If you do have an area on your property that birds use as a toilet, that is great, but do keep a check on it and remove any weeds as soon as they germinate.
Conclusion
As mentioned previously, there are quite a number of ways that weeds can get into our gardens, but if we are set up using the above simple strategies we can at least reduce the impact that weeds have on our gardens. This will make the job of maintaining our gardens easier in the long run.
More information
Making and installing a deep pipe waterer (Article)
Making a deep pipe waterer (YouTube)
Installing a deep pipe waterer (YouTube)
Making ollas from unglazed terracotta pots (article)
Making and installing ollas from clay posts (YouTube)
previous article: Weed Management Part 3: Prevention is better than cure Element A: Importing weeds
