Sorry if I'm bumping an old thread, but every now and then I come across "Operation Overgrow" proponents like the OP, who believe they can naturalize weed in the wild by spreading a sufficient number of seeds. As we'll see with some basic math, this is probably a pipe dream.
Let's start by making some assumptions:
A - Let's say that each seed scattered has a 50% chance of winding up in a suitable site (i.e., in actual soil of sufficient depth and texture). This may be an overly generous assumption if one is truly scattering the seeds, but perhaps accurate if someone is intentionally scouting locations and hand-planting.
B - Of the seeds that find a good site, let's say 50% end up with access to a water table or source to sustain them independently.
C - Of those lucky seeds, 25% will have a found a site with sufficient nutrients to sustain them.
D - Of those, 75% of the seeds will germinate.
E - Of the seeds that germinate in good spots, 10% will grow beyond the seedling stage and avoid being eaten, squashed, drowned, trampled, buried, or whatever else may happen to seedlings in the wild.
F - Of those survivors, 50% will go to seed themselves, starting the cycle anew.
So let's look at the expected outcome of 1,000 seeds, scattered in a semi-random pattern. That's 1,000 x A x B x C x D x E x F = 2.34. So basically, you'd expect 2 plants to go to seed for every 1,000 seeds you scatter in the wilderness.
Let's assume we need at least 500 seeded plants in a given radius to stand a reasonable chance at establishing a naturalized population. Some may call this figure overly generous; others may call it overly conservative. But let's make this assumption. To get 500 seeded plants from these odds, we'd need to start with approximately 214,000 seeds.
The numbers get easier or harder, depending on the percentages in your assumptions. And hell, you should probably make even more assumptions, with even more fractional/percentage multipliers in the equation. For instance, this set of assumptions doesn't account for the possibility that LE, passers by, locals, etc., discover whole populations and eradicate them on sight.
The good news is that each plant bearing seeds can produce many seeds. So if Generation 1 survives and goes to seed in sufficient numbers, then G2 and G3 will be self-sustaining or even self-expanding. But our likelihood of getting a sufficiently sizable G1 in the first place is quite low.
