Weeds grow, well, like weeds, out of the cracks of the pavement with nothing but municipal runoff to keep them alive. Meanwhile I have to work tirelessly to keep my tomato and pepper plants happy and fruitful. Why do weeds dominate a garden?
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Nobody has touched on one of the primary reasons – “weeds” get millions of tries at growing. Most plants we buy as small trays or as seed packets with maybe 100 seeds. If 10% of them survive then you have 10 plants. If 10% of a weed that dropped 50,000 seeds around then you have 5,000 weeds.
The answer is a lot of desireable plants will grow in sidewalk cracks too if you wanted to waste money throwing enough seeds there. I have petunias growing in some of mine, but petunias also produce a ton of seeds.
Many weeds are native plants or exceptionally well-adapted invasive species. They are capable in the environment where they grow.
Many desirable plants are being grown outside of their ideal habitat, which causes them to need lots of care and support. That is how they became desirable – they require skill and care to cultivate.
The weeds already live here, and easily thrive here.
Your garden plants are usually not native, and are far from home. Maybe where they’re from, they were once weeds too.
Weed that grow naturally, well goes there naturally the conditions are ideal for it. The plant you want to grow, what you brought there from somewhere else, might not have ideal conditions. That is why you need to tend your plants
Weeds, particularly invasive ones, are growing without any if their usual pressures such as grazing animals, insects, viruses, bacteria, fungi, etc.
Weeds also often have a smaller growing form, easier and faster to grow rather than woodier plants with fruit.
You can think of weed a bit like antibiotic resistant bacteria. There’s been a focused effort by humanity to get rid of plants they don’t want inside their growing spaces for millenia, so the weeds that you see today are the evolutionary result of plants struggling to stay alive throughout humanity trying to kill them since they first got the idea of planting lots of tasty plants in one area.
Weeds are weeds simply because they are resilient, spread quickly and are perfectly adapted to the local enviroment. Compare to the plants we usually try to grow that often come from another enviroment and will be much more sensitive.
But in the end its up to you to decide what you consider to be a weed for you, you can grow resilient and fast spreading plants that will be low maintenance and its only considered a weed when it starts to grow where you dont want it to grow.
Weeds are by definition plants growing where you don’t want them to grow. Since you are actively trying to kill them, only the hardiest ones will survive.
Keep in mind also, that for 10s of thousands of years, humans have been applying a selection pressure in their gardens, by pulling weeds they don’t want. The ones that can stick it out somehow, have better genes. These better genes then show up in the weed the next year. The gardener pulls 100, but 2 had particularly strong roots and so were able to come back. Repeat that about a trillion times and you have now, by the very act of weeding your garden, selected for genetically superior weeds.
Conversely…to the comments about your desired plants not being native. That’s part of it. But here, human selection is working in the other way. In the wild, a tomato is gonna want to be cherry-golfball size. This size achieves the top goal of passing forth it’s genetic material (in its seeds), without having to pump an inordinate amount of energy into a large fruit (think: beefsteak tomato. Not gonna find any of those in the wild). Now, in our breeding efforts over the millenia, we’ve developed particular desires for the attributes of that fruit. Big, red, meaty, juicy, plentiful. These are all attributes the wild plant has no care or need for. And all of those attributes require an amount of energy optimization the wild tomato just doesn’t require, because it’s local genetics are in equilibrium with what it needs to reproduce successfully. Some of the recessive genes hiding in the background may become important in the future if that local climate changes…that’s kinda why they’re hanging out in the back pocket….all of this to say, that in our selecting for our desired qualities, we’re creating plants that are less inherently tough because their energies are being genetically directed to do things that aren’t really in the plant’s best interests (heavy fruiting etc).
On the surface level the issue could be attributed to the desirable plants often being desirable due to being bred for desirable properties, which often comes at the cost of survival properties. People also often try to grow desirable plants outside their optimal climates, reducing chances of survival even further. Lumping many plants of the same type together also increases suspectibility to pests.
However, sometimes you get a plant that is both desirable and good at survival, (raspberries?) and these are what reveals that the issue is more fundamental: plants good at survival are, generally speaking, those good at spreading. If a desirable plant spreads outside the desired area, it quickly becomes non-desirable.
So it isn’t that weeds are good at survival, it’s that plants good at survival (and spreading) are weeds.
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