Weeds

When we came back from our stay in the Peace Factory after 6 weeks, we found our garden in a somewhat change shape. The paths had turned into a one metre high strip of meadow snaking through our veggie patches, which had remained fairly weeds free thanks to the mulch! The plant that had taken over the paths were mostly wild Amaranth and White Goosefoot (Chenopodium album, a close relative of the North American "Lamb's Quarters"; top photo). Both of these are edible, and quite nutritious actually.

Amaranth (photo on the right) has been the most successful weed in our garden beds too, and we have grown quite fond of it. The sacred plant of the Incas, banned after colonization and christianization, is now valiantly resisting Monsanto in various countries, especially the US. There, millions of acres of round-up ready GM crops have had to be abandoned due to a round-up resistant variety of amaranth (aka. "Pigweed"). How can one not love this freedom fighter plant?

As a matter of fact, we don't weed very much at all. Our beds are full of plants: besides amaranth and goosefoot we also have plantain (Plantago sp.), persian speedwell (Veronica persica), dock (Rumex sp.), black nightshade (Solanum nigrum), sow thistle (Sonchus sp.), scentless chamomille (aka. Bladr's Brow, Tripleurospermum inodorum), Queen Anne's Lace (Daucus carota), yarrow (Achillea millefolium), red deadnettle (Lamium purpureum), nettle (Urtica dioica) and more.

So what's the problem with weeds? Why does conventional wisdom have it that gardens need to be weed free? I have difficulty believing that weeds are always bad for all plants in the garden. What seems fairly evidently detrimental to me is if the weeds are big enough that they shade the veggies. Competition for light is something we make sure to minimize by cutting down the weeds that get too large (essentially the amaranth and goosefoot, since the others are generally smaller). We also remove the weeds that are growing very close to our veggie plants, because we presume that they are "crowding" them somehow. And lastly, the other occasion we see it as beneficial to remove weeds is for more sensitive plants: root veggies, alliums, and young seedlings seem to suffer noticeably from the presence of numerous opportunists popping up around them.

For other plants, I wonder if the benefits of the presence of these wild plants doesn't outweigh the costs. Amaranth, for instance, has a taproot, as do plantain, sow thistle, docks, Queen Anne's lace; so when these plants are growing among vegetables with a different root structure, I imagine there is a niche segregation as far as nutrients are concerned. In fact, I wonder if the taprooters don't help the other plants by bringing up deep nutrients and water that would otherwise be unavailable. Periodically, we snip off the weeds that get too big at the base, leaving the roots in the ground to increase soil fertility. By laying the severed weed on top of the mulch, it dries up and eventually decomposes back into the garden bed, returning the nutrients it acquired deep down to the vegetables. I think this kind of "chop-and-drop" green mulching should be beneficial in the long run, right? And even if the effect is not very significant compared to the nutrients brought by applying compost, manure and mulch, it still saves time and effort (cutting weeds is often easier than pulling up, and less disrupting to the soil).

Then there are all the other functions of weeds:

• They are pretty. Think of yarrow or wild carrot. Persian Speedwell is actually an alien plant that was long ago introduced for its ornamental properties.
• They attract pollinators and beneficial predators. Their flowers are often larger and more showy than veggie flowers (aside from squashes!), and help to reach an ecological balance.
• They conserve humidity in the soil when forming a ground cover. This is the case with bindweed for instance, which, though it is often maligned, is actually harmless to some veggies on which it can't get a grip, such as head cabbages, potatoes, carrots, artichokes, leeks and larger varieties of squashes (this information is from a French gardening magazine, "La Gazette des Jardins").
• They confuse insect "pests". Insects that seek plants do so by looking for green things (an insect can't tell one plant from the next from a distance; even if they are following a chemical scent they don't know exactly where it is coming from). If you only have their host plant on a brown background (earth or mulch), they'll have no trouble locating it. If they can't make it out against a green background, or if they land on a weed instead, they are likely to move on elsewhere and leave your veggies alone.

I would very much like to have some way of comparing different weed management methods, but haven't tried doing so this year. Weeds are pretty much all throughout the garden to some degree, mingling with our veggies under our benevolent gaze. Wild amaranth is our most productive garden plant, and our vegetables seem to be doing fine with it there. Why on earth would we think of removing it?