Hi, I'm a total novice gardener. I read in the planting instructions for many herbs and vegetables that you should thin the seedlings when they're small. Is this good advice? It seems to go against the idea that you should plant in high density without leaving any bare ground, but it seems so universal I thought maybe it was the best thing to do anyway. Does planting vegetables too close to each other cause them to starve for nutrients? Is the idea to plant something else in between? Is thinning good for some things but not for others? What should I do?
It depends on a whole bunch of things, not the least of all what specifically you are talking about. Mainly, the idea is that if you plant too many plants together they will not have room to grow to maturity. You can fit 3000 broccoli seeds in one square foot, but you can't grow a yield of 3000 broccoli plants per square foot.
Think of the specific plant and how much space it takes. This is Zone 1 gardening, not to be confused with a food forest or anything less labour intensive. And if you are planting seeds in place, they generally need bare earth to start off well, just like the weeds do. They are all plants.
I tend to plant thickly and eat the thinnings or transplant them around to grow on. I call it "square inch gardening"!