Weeds - Weeds - Weeds!!
Answered by: Inge Poot
Question from: Valerie Kirton
Posted on: March 14, 2003

A few years ago, I gradually started to expand my 6 x 6’ herb garden, today it has grown to 50’ x 30’. I did not do a very good job dealing with weed maintenance. Right after I till it in the spring, it looks beautiful, but within weeks the first crop of weeds appear. It’s not just a few that you can pull out little by little, it’s a carpet. It’s becoming too labour intensive, I need to mulch, but I’ve read so many different techniques, maybe you can steer me in the best direction.

Is it better to lay newspaper then cover with cedar mulch, or should I do landscape fabric and cedar mulch? If you use fabric, how do you enrich the soil? I don’t really want to go stones, but some books say herbs prefer stones to keep the soil cooler.

I’d appreciate your advice, my garden isn’t the happy place it used to be.

To fertilize after you have put down any mulch is difficult, unless you use liquid fertilizer and wash it in. It is far better to incorporate well-rotted manure in the soil in spring and it will feed the soil as it decomposes further during the growing season.

For stones to work as a mulch, the layer has to be at least 5 centimetres (2 inches) thick and 10 centimetres would be better. That is what rockgardeners do. However, the plants then have to be fed, preferably with liquid food, so that no residue stays amongst the rocks, allowing wind-blown seeds to find a foothold. But if the garden has to be re-worked, the stones make this difficult.

The cheapest method would be the newspaper method with some organic material on top to hold the papers down and make them more attractive looking. The papers do a grand job of smothering any seedling that tries to germinate, principally by shutting out the light required by many weed species for their germination. Re-working poses no problems, because the complete mulch can be tilled in.

To make the situation better for future years, try at all costs to stop the weeds from setting seeds. If weeding would disturb the crop too much, just cut the flowering tops off the weeds and compost them in a HOT compost heap or pour boiling water over the tops to kill the seeds. If you have a lot of weed flower heads, you could put them in a sunny spot with a piece of clear plastic over them, secure the sides tightly and the heat build up under the plastic will kill them. Since it might kill all other vegetation under the sheet as well, choose your spot with that in mind!

Since the weed seeds will stay viable in the soil for many years, you may want to try rototilling your garden once a week for several weeks, while you grow the crop plants in pots or flats. This will make lots of the weed seed germinate, only to be rototilled in a week later. Make sure you till after not before a rain, so that the seedlings dry out and die. Plant out and mulch at the last minute for your area!

Another strategy you can use if you have enough room is to rotate the portion of land planted to crops every year. You might plant half the land with Mexican marigold, Tagetes minuta (Richters catalogue #S3888) and the other half with your usual crop. Next year reverse the planted and rested plots. This will have the added benefit of getting rid of other soil pathogens as well.

Planting a green manure crop in the fall of one year, and tilling it under in the spring would fertilize the soil as well as getting rid of weed seedlings. Try plants such as winter wheat, rye, buckwheat or red clover. If you grow a thick crop of the plants mentioned for a whole year, they would shade out most of the weeds and not allow them to bloom and set seeds. Be sure to check for weed flowers soon after the days begin to shorten in the summer, since the shortening days trigger flowering for many annual weeds.

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