Preferred Method Of Seeding/Transplanting
When I first started gardening I followed those seed packets religiously. If the directions stated seeding every 6", then that's what went into the soil, same with transplants.
But being a small at-home gardener it didn't take me long to figure out this sure was a big waste of space. By placing one brussels sprouts transplant every 18 to 24" I had all kinds of space for months that was accomplishing nothing until that plant grew and matured.
So I ended up starting to place a low grower underneath a tall grower and now I was getting two kinds of harvest from the same soil area. I was just careful about placing a shade-loving variety under the tall variety. So now I generally place radishes, lettuce, spinach and other seeds like that under my broccoli, brussels sprouts, cukes/squash and other plant families as I grow.
Trying it this way I soon learned I don't have to keep ripping out my yard to make my garden area bigger. I just had to do a little homework and figure out which plants would be compatible together because one is high, one is low. One will be ready for harvest early while the other needs to stay in ground for more time.
I also realized broadcasting seed instead of all those single seeds in a row gave me more harvest also. Who says radishes, carrots, spinach, leaf lettuce etc. can only grow in single file? Make a two foot wide row of seeds and then as the plants mature you just start harvesting as you would thinning. As you are harvesting you are automatically making more room for the next plant to grow in.
Another easy fix is vertical gardening. Any plant (like squash/zucchini, melons, cukes, pole beans etc) which grow long winding tendrils take up tons of space on the ground. But give that plant a steady support to climb up and now it takes mere inches to a foot instead of 3-5 feet of space. So instead of putting in one plant you can now put in five plants, maybe more just by letting that plant go up.
Because of these methods I now get double, triple or even more the harvest from my garden with out adding even an extra inch of space.
Give it a try if you have a small area or if you just wish to find a way to increase your yields etc. It doesn't take long for you to find this truly works.