There are many benefits of raised bed gardening, one of which is the ability to plant far more densely than in-ground gardening.
With raised beds, there’s no need to plant in rows, except for vining beans and peas and only because they need a single-plane vertical support.
Over the years I’ve developed a simple system for spacing summer vegetable plants in raised beds. It’s a secret system, but I’m sharing it with you.
I start with cylinders formed from three zip ties (each about six-inches long) plus one sheet of concrete reinforcing mesh measuring three and a half feet tall by seven feet wide, with openings approximately six inches across.
To make the cylinders, I first lay each sheet on the ground, then pull the short ends together. I lace zip ties through the mesh to hold the ends of the sheets together—one at the top, one at the bottom, and one in the middle. When I turn the cylinder upright, it forms a freestanding cage.
The cylinders then determine how I space plants in raised beds.
For example, each cylinder supports:
Two tomato plants, planted inside the cylinder
Six cucumber plants, three spaced evenly around the inside of the cylinder, three spaced evenly around the
outside (arrange so the inside and outside plants are staggered)
Three melon plants spaced evenly around the outside of the cylinder
I plant eggplants, basil, cilantro, peppers, and so on, in the spaces between the cylinders.
While spacing is important, so is having at least two raised beds to work with, especially if you grow edibles in the nightshade family (tomatoes, eggplants, peppers, tomatillos, potatoes). Plant all those plants (except potatoes, which do better in a half whiskey barrel) into the same bed.
The next year, move them all to the second bed. The third year, they go back in the first bed (or if you have many beds, move them to any bed where no nightshades grew the year before).
This kind of rotation is key to success, and here’s why: Nightshade plants are especially susceptible to root-knot nematode, leaf viruses, fungi, and all sorts of other pathogens that are deadly to the plants. When the pathogens’ favorite food is in the ground, the pathogen populations explode.
The next year, the pathogens are still hanging around in high numbers, ready to go to town on the new seedlings.
Rather than plant nightshades there, go with edibles that the pathogens don’t seem to bother: melons, squash, cucumbers, beans, peas, basil, etc.
Without their favorite food, the pathogens’ populations crash. So, by year three, it’s safe to plant nightshade plants there again.