Weeds also smother and reduce fruit production plus invite insects. Not many vegetables have the root system that weeds have and depend on care and room to produce. If you are not going to weed then you need to mulch quite heavily.

...along with what's mentioned...some weeds, such as johnson grass, suppress the growth of some neighboring plants via chemicals they release in the root zone as a means of competitive advantage.

Not such a dumb question. As you surmised, some of the weeds will compete with your vegetables for nutrients, as well as water and sunlight. Some may serve as an attractant or reservoir for pests or diseases.

On the other hand, some can benefit the garden as they attract beneficial insects (tiny flies and wasps that parasitize the pests that will feast on your veggie plants) and some have very long taproots that go deep into the soil and mine nutrients, bringing them closer to the surface.

There is much more going on out there than meets the eye. Apparently, there is a whole complex of organisms (including insects, crustaceans, plants, bacteria & fungi), chemicals and interactions. I've attended a few introductory-level programs on sustainable landscape design and permaculture and it's a fascinating field of study.

I hope someone here has some more information, but you may want to check out the permaculture forum.

Not the dumbest question, I would say quite the opposite. It shows you want to know whether or not you should do something for a reason other than "because everyone else is doing it". :) And I think it leads to the interesting questions of "how much weeding is really necessary?" and "is there something I can do besides weed to help the garden?" and even "what is a weed and are they all equally bad?"

The best part is that everyone has a slightly different answer to these questions and there is so much room to learn and then to express your individual self in your garden.

I don't really have anything to add to the above answers, they seem to cover most everything I would say about why weeding has a place in garden maintenace.

Actually, the OP's question is a valid one.

In my opinion, most vegetation that we call WEED, are critical when our plants are tiny. They crowd out the root area and compete for nutrient, light. But when, for example, a tomato plant is 5 foot tall some tiny weed are not going to do anything significant and some times could be beneficial as a ground cover. When I sow directly things like PARSLEY, ONIONS, LETTUCE... I hunt those tiny WEEDS rigorously. and there is no other solution because I plant things real tight. No way to mulch 'm.

Another reason, we do WEED our gardens, is just for visual effect to please our eyes and show the character of the things we plant and grow . For example, in a flower garden flowers and some WEEDS can get along just fine but they disrupt our perception of what a flower garden should look like.

Very good question, and interesting discussion.

What I take out: quack grass, twitch grass, morning glory, anything that vines.

What I leave in: Dandelions (cools the soil, sometimes I eat them, brings up nutrients from below and when I do pull them out, I add them to compost.) Dock (seems to be a catch crop for some pests), Queen Anne's Lace -- pretty, and tall, I like the way it looks, buttercups, daisies, yarrow, black eyed susans, pretty much anything that flowers, as they feed the bees and other pollinators, CLOVER. I am physically incapable of pulling up clover. It fixes nitrogen and feeds the soil, and also the bees love it. I have red clover, purple clover, white clover, yellow clover. I mulch with hay, so lots of interesting weed seeds plant themselves every year.

As you might guess, my garden is full of weeds. I grow all of the vegetables and a lot of the fruit for 2 people (with some to give away) each year. So, if you have the space and the inclination to share the sunshine and nutrients with interlopers, you can have sort of a festival of things growing and still be successful.

Of course, everything everyone said above is true, too. This is just one way to do it.

My first year gardening I visited a friend's garden and was surprised to see lots of very happy dandelions and other weeds growing among her vegetables. When I commented, she said "I don't worry much about weeds." (Later she added: except quack grass--that I pull out.)
She oversees the garden at a Zen monastery now.

This post was edited by elisa_Z5 on Wed, May 29, 13 at 1:29

These are interesting answers. I think the best one is out-competition. A "weed" is something that grows in my garden that I didn't plant. Such things are there because they are naturally selected to be things that out-compete the things they grow with in that environment. "Weeds" generally are vastly more forgiving about water and nutrients than cultivated plants. Why? Because they have root systems that seek out that water and those nutrients. They are biochemically superbly adapted to where they decide to come up. Our garden vegetables aren't bred to outcompete. They aren't bred to be biochemically superbly adapted to where we plant them. They're bred to produce things we like to eat, and to be more or less forgiving about where we plant them.

I think it is true that some plants release chemicals in the root zone that interfere with other plants, but rather few. But if my veggies grow best being spaced out in my plot, that's because we don't want them to compete with each other. Other plants that fill those spaces will do exactly that. One way these "weeds" outcompete is by rampant fertility. I may leave some low growing, uninvited plants to help provide groundcover, but you can bet that those plants will be rapidly reproducing. They'll want to take over the plot. Can't think of many veggies that will try to do that.

I'd add that problem weeds are mostly native to the local region, and are therefore much better-adapted to the climate, soil, etc, than most vegetables, which are "imported" (so to speak) and made to grow only under special conditions (amended soil, fertilizer, specific time-frames, etc). Of course, you can cultivate similar qualities in veggies for which you save the seeds of the most successful plants, but it would take a long time to see similar results, probably much longer than one lifetime. It's no wonder weeds grow so prolifically in comparison.

In general, to the original poster, I think it's great to ask questions about the habitual assumptions and practices of any practice. It makes us think about why we're doing what we're doing as well as share ideas about how to do it better. Conventional wisdom is often right, but it's often wrong too.

I agree with saysonn, it has all to do with the size of the crop plant, as well as size of the crop seed and type of weed. Big-seeded crops like corn and beans, for example, can compete with weeds somewhat better than small-seeded ones like lettuce, carrots.

One of these days I'm going to get with it and try stale-bedding for certain crops, especially carrots.