In nature, most seeds falls off the plant and lie on the surface. They germinate ok.
So why do instructions in some seed packets specify planting seeds upto an inch in the soil?
- Not all seeds should be buried and for those that do the depth varies. Lettuce seeds need light to germinate and should be strewn on the surface and then tamped down to make good soil contact.
The size of a seed is sometimes said to relate to how far down to plant it based on some proportion (2 or 3 times, for example). But the best strategy is to RTF … seed packet.
- Random strewing is highly lossy. A good proportion of the seeds get eaten, don’t germinate right, etc. For vegetable, flower gardening and farming you don’t want to lose 90%+ of your seeds. So you plant them the right distance in the soil.
Lots of things work better if you improve on nature.
If plants could have evolved practical means of pushing their seeds into the ground, weeding around them, and pouring Miracle Gro on them every day, I’m sure they would have.
That’s part of the reason human babies have a higher survival rate than grass seeds.
As ftg said, some seed does need to be on the surface, because some species need light to germinate.
Other seed won’t germinate in light and needs darkness; so it needs to be buried. In nature, seed that needs darkness gets buried or otherwise pulled down into the soil by squirrels and other creatures, by being stepped on and pressed into the soil, by deposits of silt by wind and/or water, by accumulations of leaf mold, and so on.
Most vegetable seed doesn’t much care whether it’s in light or in darkness; but it does care whether it gets dried out after the germination process has started but before it’s got roots to reach down for water; that can kill it. It’s much easier to keep seed consistently wet if it’s covered by soil.
Burying seed too deep for the particular species can result in its not germinating, or in its germinating but not having sufficient energy reserves to push its first leaves up above the soil surface, where they can produce more energy from sunlight. So seed buried too deep will often die; though in some species it may not start the germination process until/unless it’s raised up nearer the surface (some brief light exposure may be needed).
If?
I get your post except the Miracle grow part. Most seeds I have germinated have clear instructions on not fertilizing until they have grown a few leaves.
Most seeds in nature do not, in fact, “do OK”. The vast, vast majority do not reach adulthood.
Think of an oak tree. It can live for hundreds of years, and each year produce hundreds of thousands of acorns. Out of those tens of millions of acorns, how many eventually become mature oak trees? Assuming that the population of oak trees is stable, one.
That’s a bit of an extreme case, as most plants neither live as long as oak trees nor produce as many seeds per season, but it remains true that most plants produce many, many seeds, of which on average only one survives.
OP: Are you germinating indoors to keep seeds and seedlings from being devoured? Any seeds we strew about are happily taken by local small wildlife. Can you accommodate a greenhouse or equivalent?
In nature, a plant broadcasts a lot of seeds in the hope that a few make it. Some of the successful ones are covered by things like leaf litter, dust and windblown dirt, and otherwise hidden and protected by seed predator’s. Seeds and nuts are a major food source for many animals and insects. And then there is the issue of keeping them moist enough, for long enough, to germinate and become a seedling. Just a small cover of soil really helps with all of that.
Along with all the other points about inefficiency in nature, there is another big issue.
The seeds you are getting in those packets mostly don’t produce plants that naturally evolved in the absence of humans. Even heirloom seeds are generally the results of millenia of selective human intervention to produce crops we want. Some of our food crops look very little like their closest living natural relative. We were doing that even before we had scientific theories guiding the efforts. Simply saving the seeds from the best crop every year to plant the next year selected for the traits humanity valued.
It really ramped up about a century ago. We figured out that we could force higher rates of mutations by injecting the plants with mutagenic chemicals or exposing them to radiation. We could then grow the resulting seeds. Some would have interesting properties that we could then breed/crossbreed to retain. We had been doing that even before figuring out more modern genetic modification techniques.
The seeds you buying off the shelf are mostly tailored to thrive in an environment that includes the efforts of human farmers. You shouldn’t expect them to do well without your involvement. We are their natural environment.
So that’s what I’ve been doing wrong.
And oaks have, indeed, found a way to get some portion of their seeds “pushed into the ground”, by way of squirrels and various birds, who dig them down to retrieve them later, but forget about them! (Of course, a greater lot simply get eaten.)
If I don’t bury my tiny Basil seeds, the first rain that comes along washes them all down to the low end of my garden. Cruddy germination and overcrowded plants are the result. It doesn’t take more than a little dirt, or a few layers of leaves to prevent that.
A lot of ‘natural’ reproduction relies on producing vast numbers of offspring in the hope that a few will survive. Although a single female salmon can lay 1,000 to 17,000 eggs, very few of those eggs actually survive from fertilization to maturity. An average of 3 fish returning for every parent fish that spawns would be considered good.
Go back to the 19th century and humans used the same logic, albeit with lower numbers.