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I have heard constantly that weeding is a must for growing healthy vegetables else the weeds will "steal nutrients" from the plants you want to grow and your garden will produce less.

How true is that statement? I've been reading about organic agriculture and permaculture which tend to state that sharing the space isn't as bad as traditional agriculture seems to think.

For sure, some weeds can kill other plants if they strangle them or cover the light. But is merely sharing the same soil damaging? How true is that "stealing nutrients" narrative?

FWIW, this is my first season with a garden and it has been producing some veggies, while sharing the soil with purslane.

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    Purslane can be useful, since it tends to stabilize the microclimate and increase humidity at ground level. It is also deep rooted and by breaking up the soil can improve the root system (and therefore the ability to access ground water ) of other plants growing with it. Plus, you can eat the leaves, stems, and seeds, and it is the richest known plant source of one essential omega-3 fatty acid. Whether you call it a "weed" is up to you :)
    – alephzero
    Jul 20 at 7:21
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    Yeah, I found all that out while researching this "weed". And many people told me to remove it because it steals from the plants I actually cultivated. So in the sense that I didn't plant it and never had eaten it before it grew by itself, it's a "weed". Basically I think I may be leaving out some productivity if I don't strip it out, which, given my livelihood is not dependent on the amount of veggies I grow, seems to be fine by me Jul 20 at 8:14
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    "which tend to state that sharing the space isn't as bad as traditional agriculture seems to think." - Notice they don't claim that it is a non-negative nor does it give a ball-park percentage. Let's pretend that the presence of weeds produces 10% less harvest (regardless whether that's by weight or physical count). Okay so you only get 9 tomatoes instead of 10. That difference is a bit more significant when you're talking about a farmer with hundreds of acres. If manual weeding isn't worth your time for 1 extra tomato then that's your prerogative.
    – MonkeyZeus
    Jul 20 at 15:36
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    Also worth noting that if nutrients are being stolen by weeds then the harvest you do get could be less flavorful.
    – MonkeyZeus
    Jul 20 at 15:37
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    There is a middle path to pulling or permitting: periodically chop weeds down and let them decay where they fall. This is way less work than eradication and (eventually) returns some of the "stolen" nutrients back into the soil, gives more light to valuable crops, yada yada.
    – dandavis
    Jul 20 at 16:46
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The stealing nutrients narrative is, in the general case, true.

There are certain plant combinations which work well together, a classic example being "the 3 sisters" of corn, beans, and, squash. Similarly rotating crops can be beneficial as different crops add and remove different elements from the soil.

Another strand of evidence, I have a little experience with growing nightshades (tomato, eggplant, peppers) commercially in a hothouse, can be taken from commercial farming practices. The plants are pumped with nutrients and there is very little nutrients left in the runoff, meaning the plants are consuming it. More plants competing for the same nutrients will give each less.

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    Penn State agrees with you: extension.psu.edu/…
    – Jurp
    Jul 20 at 13:40
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    There are also plants that complement each others' nutrient needs. Lupins are said to provide other plants with nitrogen, but I don't know enough about this to contribute an answer.
    – henning
    Jul 20 at 13:46
  • "The plants are pumped with nutrients and there is very little nutrient left in the runoff, meaning the plants are consuming it" - That doesn't seem to square with the magnitude of the eutrophication problems caused by agricultural runoff.
    – Vikki
    Jul 21 at 16:56
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    @Vikki Note I said "very little", not "no" runoff. I understand (having only briefly owned a fish tank) aquatic environments are very sensitive to nitrites and nitrates, so even small amounts of runoff will impact waterways. By analogy - People that eat lots of food (feriliser) get fat but also have bigger bowel movements (runoff). If more people ate the same total quantity of food, people would not get as fat. (weeds sharing nutrients)
    – davidgo
    Jul 21 at 20:26
  • There's also certain species of trees that can share nutrients through their root systems - the conifers give glucose to the deciduous trees in the winter, and in exchange the deciduous trees give glucose to the conifers in the summer.
    – nick012000
    Jul 22 at 2:44
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It really depends on what you're growing, how you're growing it, what you expect from your garden, how big the weeds are, how close they are to your plant, how many weeds there are, how fertile your soil is, how the specific weeds interact with your plants and each other, etc.

Plants can compete with each other, produce chemicals to inhibit other plants, and stuff like that (but they might do beneficial stuff, too, in some cases). Calendula can kill nitrogen-fixing microbes that are important for beans. Black walnut can inhibit lots of plants; same for wormwood. Sunflowers are said to inhibit plants somewhat.

Muskmelons will smother most weeds, in my experience (so if you're growing those, I wouldn't worry a terrible lot). Watermelons let more weeds through (and grasses, if present, can be problematic); watermelons still grow pretty well with weeds, though (but if you like to pull weeds up, grass is hard to deal with there, as pulling it up can disturb the watermelon roots).

Here are reasons to weed:

  • Aesthetics
  • To prevent more weed seeds from spreading (a single weed dropping seeds can mean loads of them next year)
  • To prevent weeds from choking out the plants (not just competing for nutrients)
  • To be respectful to your neighbors (neighbors don't usually want your weeds spreading to their yard)
  • It might be illegal in some areas to let weeds grow.
  • It's harder to navigate and find stuff in a garden full of weeds.
  • Weeds sometimes get diseases (which in theory could spread).
  • If you container-garden, weeds are a bigger problem (if you have weed seeds in your containers, which not everyone does), because nutrients in containers are in more limited supply, and so is space for roots.

Reasons not to weed:

  • It's extra work. Is the extra production worth it to you?
  • You can learn how to grow vegetables better with weeds. If you want to know if it works, asking people who always weed their gardens isn't going to give you the answer. You need to find someone who has really tried to grow vegetables with weeds, and learned all the tricks to assist in doing so (or you need to teach yourself).
  • It's good for the insects and biodiversity of your garden. Weeds can be great food for grasshoppers, or whatever, if you like to nurture them. Butterflies will lay eggs on weeds. I saw a whole bunch of wasps enjoying purslane flowers, today. I was wondering what was attracting so many of them to our garden (I think it's the purslane, as it has become a frequent weed, especially in our containers).

If you don't want to worry about weeds very much, growing in the ground with black plastic over it keeps most of them away. You still have to weed right around the plant, though (if you weed), but it's a lot less to worry about. Shredded wood mulch can also keep weeds out, but it's more expensive and needs to be put down more often; however, mulch can keep weeds out from around the base of the plant, too, whereas black plastic can't. Mulch nourishes the soil, and you can water all over it instead of just where the plant is.

I personally believe that you can breed and acclimate plants to grow better with weeds, but I don't know anyone who is pursuing this, currently.

You can get a good harvest with weeds--but weeds can prevent a harvest altogether, too. It depends.

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    Comments are not for extended discussion; this conversation has been moved to chat.
    – Stephie
    Jul 21 at 20:56
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Weeds are often edible, healthy, and nutritious. Native weeds are even better as they are designed to be compatible with the environment.

Find out if the weeds are safe to eat, and consider letting them flourish. They will grow easily and require less work (and often water) than many "conventional" vegetables.

Like all plants, sometimes only certain parts of weeds are safe to eat.

Remember, "weeds" are plants too! And they show up, usually, because they thrive naturally in your environment.


Update: A good comment regarding the flavours of edible "weeds" was posted. The flavours of "weeds" vary greatly (from sweet to sour... from strong to mild), but there are some edible varieties that are a bit too bitter for my taste buds. To counter this, here are a few tips:

  1. Blend them and drink them as a shot.
  2. Blend them and mix them with other ingredients to reduce any bitter taste (apple juice can be a great mix-in).
  3. Put them in a salad and add some oil and vinegar dressing. I find the vinegar really counters bitterness well... especially balsamic vinaigrette.
  4. Put them in a salad and add seeds or nuts. The contrast in flavours can be quite nice.
  5. Bake with them as an ingredient.
  6. Add them to soups or stews.
  7. Research any medicinal properties (but be careful that it's not actually dangerous or toxic... finding accurate information often isn't easy).
  8. Feed them to animals! Some animals love the taste of certain plants that humans commonly call "weeds". Many even consider them a delicacy. Nepeta cataria is probably the best known example... it's the weed we commonly call "catnip".
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    Note however that "edible, healthy and nutritious" doesn't necessarily mean they taste good. Also the edible element of weeds is usually profoundly seasonal and may be small, so whilst they'll grow easily, you may not get much edible benefit from them. Blackberries are tasty, but you've got maybe a month or two of fruit and that's it. Only nettle tips are worth eating, which limits you to a short period in April-June. And only young dandelion leaves are palatable (old leaves are very bitter).
    – Graham
    Jul 21 at 9:36
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    @Graham Good point about the range of flavours. I've updated my answer with a handful of tips. Jul 21 at 14:22
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It's important if the 'weeds' (really just other plants) do things like

  • grow faster and thus block sunlight (what leads to empty forest floors)
  • grow as creeper vines that wrap and choke the other plants
  • grow much faster (commonly invasive) and out grow and consume the vegetables*
  • change soil ph or content over time. Pine forest and needles for example.

* This is the one where the nutrients might be drained.

It is also worth mentioning the advantages of the right kind of 'weeds'

  • cover crops like clover (nitrogen i think) which would be low.
  • retaining moisture and keeping the soil from quickly drying out between rains
  • reducing temperature during hot spells - grass is cooler than hot baked dried mud

How does the nitrogen get over into the grass? The legume is able to use this nitrogen to grow, but the grass surrounding the clover plant does not have access to that nitrogen. The grass can get that nitrogen through an indirect process. As the legume grows, producing new leaves and roots, there is the constant death and replacement of roots, root hairs, and leaves. As these plant parts break down in the soil, the nitrogen in these parts is released into the soil, then becoming available to the grass for uptake and use in growth. The nitrogen transfer is due to legume plants dying and the nitrogen being recycled.

Put another way perhaps - "Mulching also helps" -me

https://www.drovers.com/news/beef-production/how-do-clovers-add-nitrogen-pastures

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