Are these weeds?

Question

This is the first year I'm taking care of a vegetable patch. It's a total of ~6m² which I have divided up into smaller areas. I have sown some seeds two weeks ago which are beginning to sprout. However, in most patches there are two types of plants coming up. I think I have identified which is the weed, but wanted to check with you to be absolutely sure, especially because seedlings can often look so different from the final plant. In the pictures below I have circled what I think are weeds, in a patch with dill and spring onion.

The reasons why I think these are the weeds:

• They appear in every patch, while there is more variety in the other type of plant found in each patch.
• They don't look like what I would expect from dill and spring onions.

The reasons why I'm not sure:

• I also have patches with spinach, leaf celery, arugula, and Swiss chard. There it is much more difficult to distinguish two types. This may be because the vegetable hasn't come up yet. But it could it not also be that these are all, say, Swiss chard, sprouts, and have been distributed over the garden by wind / birds? To my inexperienced eye they look a bit like Swiss chard seedlings seen here (image permalink).
• I have some patches which are still empty, because I'm waiting to transplant some other vegetables there. There are virtually no plants of the type that I'm identifying as weeds in these patches, which suggests that they were in fact sown. (On the other hand, I did not water these patches, which could also explain the lack of weeds?)

Finally, if it is not certain that they are weeds (especially in the Swiss chard patch, for example), is it bad to leave the plants there to wait until they are bigger and can be identified better? Will this seriously hinder the vegetables in growing and/or make it more likely the weeds will return?

Answer 1

You've got at least two different things circled, based on differences in the cotyledons. They are dicots (two cotyledons) so none of them are onion (a monocot, thus easily distinguished from any dicot.) There appears to be some dill between them in the top picture (long, bent cotyledons which are fairly distinctive)

There will be no particular negative effect from allowing them to develop to the point that you can distinguish weed from plant. Eventually you may learn to know what's a weed and a plant in your growing mix at a very early stage - certainly any dicot can be considered a weed in a monocot planting, and vice versa, but it's also possible to have "volunteer" plants (weeds that are crops - dill has been an example in my gardens in the past - planted one time, self-sown thereafter, and you learn to know what they look like and leave them to grow where they are not n the way of other plants, and weed and eat them where they are in the way.)

Answer 2

1. About the word "weeds" :

   Spontaneous plants are usually the indigenous (or previously sown, as @Ecnerwal stated) best fit for a particular patch of land.

   Considering that an uncovered soil is a state to avoid (and nature will make everything to solve such degradation), letting weeds grow can be a good idea until they reach some critical dimensions (see 2.).

   Known as bio-indicator property, plants' seeds break their dormancy on specific soil conditions (water, temperature, compaction ...).

   Spontaneous plants perform very well where they grow and serve some practical & ecological functions : organic matter production (for mulching & composting), nitrogen fixation, host garden auxiliaries, creating favorable micro-climates.

2. When to cut them :

   Knowing needs of plants you cultivate, you'll have to cut weeds at different points.

   One nuisance is shadow. When weeds limits your plants exposition to sun, you can cut annoying leaves or the whole plant.

   Another nuisance is water & nutrient concurrency. Weeds can use some other required growth components presents in soil, reducing your plants inputs.

   The thinner is the soil and the more scarce are water & nutrients, the more you'll need to control the weeds to avoid them eating your plants foodies.

   Another nuisance is roots & constant sprouting. Some weeds like nettles or egopodes (or poaceaes) grow dense roots that occupy soil space & allow them to deeply sprout inside your cultures, making extraction difficult.

   In this case, try to remove the more roots possible while preparing the soil then systematically cut new sprouts.

There is a whole lot of other potential nuisances, but most of the time you should seek the good uses to make with spontaneous plants.

These are true present of nature : no need to sow, and a lot of services rendered.

Good luck identifying these plants, and try to determine why they grow in your garden at first : it could tell you on which points to focus in order to improve your soil quality.