I recently received a comment from someone who only wanted two crops in their garden and wanted to know how to space those crops.
If you want a lot of peppers, or any other crop in bulk, and you are not sure how to space it in your garden, I would suggest consulting how many of that crop should be planted per square foot. Larger plants, and plants that need to be trellised, or vertical, should be on the north of your box while smaller plants can be positioned near the south. In the case of peppers, normally a person would have two or three pepper plants in their whole garden, not eight or ten. It’s best to space them out for several reasons: one is pest and disease protection, another would be for staggered harvest, and a third would be just for good looks. Remember we are looking for a quilt look to our garden. However, if you want a lot of one thing, such as peppers, then they can all be placed together, even different varieties, so it makes harvest easier. This is all laid out in my second book, CASH from Square Foot Gardening.
The idea of that book is to raise a crop to sell, as if you were a farmer, not a home gardener. In that case, you want a large harvest all at once to go to market. If you read that book you will see that an entire 4×12 bed was planted with one crop, either all at once, if it was a summer fruit crop, or the harvest was staggered in a wave action, if you wanted a continual cool weather crop, so that also depended on the harvest you were looking for.
Concerning tomatoes, if you’re planting a bush variety, if you’ll check the book, you’ll see it needs a 3×3 area. This allows it to grow large and produce enough crop for the season.
The only time we plant one tomato plant per square foot is when we trim that plant to a single stem and grow it vertically up a tomato frame. Those are called vine plants versus bush plants.
In a normal 4×4 you could plant two ways, depending on the crop type. With vine tomatoes, you can plant 4 tomato plants along the north side where you have space for a tomato tower, or trellis, to grow them on. With bush tomatoes, you can put one in the middle of a 3×3 area, or one per 9 square feet (boxes). The outer ledges would contain 7 more squares and you can put peppers in there, since peppers and tomatoes are usually seen together in the garden and on the table together, or another crop of your choosing. However, I would not plant vine tomatoes with bush tomatoes. Keep those varieties separate.
It might help to draw a picture of a 4×4 square bed with 16 squares and then you can see much better how many plants and of what varieties can be put in a 4×4. Just keep in mind the spacing for each particular crop.