What Is Square Foot Gardening and How the Grid Works
As an Amazon Associate we earn from qualifying purchases.
What is square foot gardening? It is a method of intensive planting in which a bed is divided into one-foot squares, and each square holds a set number of plants based on their mature size. Instead of planting in long rows, the gardener works in a grid. This article explains how the grid works, why the spacing rules matter, and what university extension material says about the method and its limits.
Quick answer
- Square foot gardening divides a bed into a grid of one-foot squares.
- Each square is planted with a fixed number of plants, based on crop size.
- The classic model is a 4 by 4 foot bed with 16 planting areas.
- Dense planting shades the soil, which helps suppress weeds.
The basic idea
The method replaces rows with squares. A gardener builds a bed, lays out a grid with string or thin boards, and plants a different crop in each square. The Washington State University Extension material describes the grid as the core of the system: “The grids in your SFG should be “prominent and permanent” (Bartholomew).” A visible grid makes it easier to plant, harvest and rotate crops.
The layout is not required to be square in every case. The WSU publication notes that “While the classic model is a 4×4 foot square, providing 16 planting areas, a SFG can be long (such as 16 x 2 feet), very small, or even a container or pot.” The principle is the one-foot unit, not a fixed bed size.
How plant counts are set
Each square holds a set number of plants, and the number depends on how large the mature plant will be. The WSU publication gives the general logic: Bartholomew “has developed guidelines for the number of plants per square foot, based on the size of the” plant. Large crops take one plant per square, while smaller crops can take many more.
The WSU material gives examples by size. Extra-large crops such as nightshades, cabbage and broccoli take one plant per square, while large crops such as kale and potatoes take four per square, and medium crops such as bush beans and spinach take nine per square. The counts follow the spacing that each crop needs to reach full size, so the square is filled without overcrowding.
Why dense planting reduces weeds
Packing plants close together has a side effect. Leaves from neighboring plants shade the soil, which limits the light that weed seeds need to sprout. The WSU publication puts it this way: “intensive planting suppresses weed growth, as the leaves of the plants quickly fill in and shade the soil.” That is one reason the method is often described as low maintenance.
The effect depends on the crop, the spacing and how quickly the canopy closes. Bare squares between plantings or crops that grow slowly will not shade the soil in the same way, so weeding is still needed in some cases.
The soil and the bed
Square foot gardening usually uses a raised bed with a soil mix suited to dense planting. The WSU material describes a mix built from equal parts of vermiculite or perlite, peat moss and compost, and it notes that coconut coir can replace peat moss. The mix is meant to drain well while holding enough moisture and nutrients for closely spaced plants.
The bed itself is usually raised so the soil can be deeper and better controlled than the native ground. The WSU publication describes the approach as simple, and it treats the soil mix as the key part of the system rather than the frame.
Why the grid matters for planting
The grid is a planning tool as much as a planting pattern. A gardener can plan crop rotation, succession planting and harvest timing square by square. The WSU material notes that succession planting is easy in this system, because when plants in one square are finished, that square can be replanted without disturbing the rest of the bed.
The grid also reduces seed waste. Because each square has a set plant count, the gardener plants only the number of seeds the square needs, rather than sowing thickly in a row and thinning later.
Planning a grid on paper
Before building a bed, many gardeners sketch the grid on paper, marking each one-foot square and writing the planned crop and plant count inside it. This makes it easier to see how many squares each crop needs and to spot crowding before any seed is sown. The WSU material notes that the grid should be easy to see, which is the reason it recommends string or thin boards for laying it out.
A plan also helps with succession planting. Squares that will be harvested early, such as a fast crop, can be marked so that a second crop is ready to go in once the first is cleared. The method works best when the plan is kept up to date through the season.
How we chose
The source in this article was chosen because it could be opened and read at the time of checking, and because it comes from a university extension service. Only statements found in the fetched text are quoted. Other extension pages returned errors when checked, and Wikipedia and commercial pages were not used as sources for the claims in this article.
What we could not verify
Several details that often appear in square foot gardening guides were not confirmed by the extension source used here. These include the exact yield per square, the claim that the method uses a specific amount of water and the exact timing of successive plantings. Those points are not quoted because the checked text does not state them.
What the sources do not say
The source does not compare square foot gardening yields with row gardening under the same conditions, and it does not give a measured figure for how much less water or fertilizer the method uses. It also does not give a single standard for every climate or bed depth. Those questions need controlled comparisons that the sources used here do not provide.
Frequently asked questions
How big is a square foot garden?
The classic model is a 4 by 4 foot bed with 16 one-foot squares. The WSU material notes that the bed can be longer, smaller or set in a container, as long as the one-foot grid is kept.
How many plants go in each square?
The count depends on the crop. Large plants such as cabbage take one per square, while smaller plants take more. The WSU examples give one per square for extra-large crops, four for large crops and nine for medium crops.
Do square foot gardens need fertilizer?
The WSU publication describes the method as needing no regular fertilizing when the soil mix is built well, but that is a description of the method’s design rather than a measured result. Gardeners should still watch their plants and adjust the mix or feeding as needed.
Why is the grid kept permanent?
The WSU publication quotes Bartholomew that the grids should be “prominent and permanent.” A visible grid makes it easier to keep track of which crop is in which square and to plan replanting.
Can square foot gardening be done in containers?
Yes. The WSU publication says a square foot garden can be “very small, or even a container or pot,” so the grid can be used on a smaller scale.
For related reading, see how to make garden soil better and how to grow herbs in pots.
Sources
- Washington State University Extension (WSU Skagit County Master Gardeners), “Square Foot Gardening – Simple, Versatile and Fun!,” https://wpcdn.web.wsu.edu/wp-extension/uploads/sites/2056/2018/10/Square-Foot-Gardening.pdf (opened 2026-10-27).
