Calculating Plants Per Square Foot: Number Of Plants Per Square Foot Guide


By: Anne Baley

An engineer named Mel Bartholomew invented an entirely new type of gardening in the 1970s: the square foot garden. This new and intensive gardening method uses 80 percent less soil and water and about 90 percent less work than traditional gardens. The concept behind square foot gardening is to plant a certain number of seeds or seedlings in each of a series of foot-square (30 x 30 cm.) garden sections. There are either 1, 4, 9 or 16 plants in each square, and how many plants per square foot depends on what variety of plant is in the soil.

Plant Spacing in a Square Foot Garden

Square foot garden plots are set up in grids of 4 x 4 squares, or 2 x 4 if set up against a wall. Strings or thin pieces of wood are attached to the frame to divide the plot into equal square foot (30 x 30 cm.) sections. One type of vegetable plant is planted in each section. If vine plants are grown, they’re generally placed in the back to allow for a straight trellis to be installed at the very back of the bed.

How Many Plants per Square Foot

When calculating plants per square foot (30 x 30 cm.), the most important thing to consider is the size of each adult plant. In the initial planning stages, you may want to consult a plant per square foot guide, but this will only give you a general idea of garden plans. You’ll rarely have a garden book or website with you in the yard, so figuring out your own plant spacing in a square foot garden is an essential thing to learn.

Look on the back of the seed packet or on the tab in the seedling pot. You’ll see two different planting distance numbers. These are based on old-school row planting plans and assume you will have a wide space in between rows. You can ignore this larger number in the instructions and simply concentrate on the smaller one. If, for instance, your carrot seeds packet recommends 3 inches (7.5 cm.) apart for the smaller number, this is how close you can get on all sides and still grow healthy carrots.

Divide the number of inches per distance you need into 12 inches (30 cm.), the size of your plot. For carrots, the answer is 4. This number applies to horizontal rows in the square, as well as vertical. This means that you fill the square with four rows of four plants each, or 16 carrot plants.

This method works for any plant. If you find a range of distance, such as from 4 to 6 inches (10 to 15 cm.), use the smaller number. If you find the rare fraction in your answer, fudge it a little bit and get as close to the answer as you can. Plant spacing in a square foot garden is art, after all, not science.

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Pansy Square Foot Gardening

Seed to Harvest/Flower: 20 weeks

Weeks to Maturity: 14 weeks

Indoor Seed Starting: 14 to 16 weeks

perennial in Zones 7 to 10,

Earliest Outdoor Planting: early

Additional Plantings: not needed

The best word to describe pansy flowers is "adorable/5 The little "faces" look up at you like they offer hope for a lovely spring after a cold winter and as a last hoorah of color in the fall. Even the flowers without the actual black blotches look like happy faces. Pansies come in so many colors and color combinations that its difficult to keep up with the changes and even more difficult to choose which ones to plant. They are easy to grow, as long as you remember that they like cool, moist conditions. When the weather gets hot and dry, plan to either discard or move your pansies. Tiny pansy-like flowers that crop up all over are Johnny-jump-ups, a self-sowing diminutive cousin to the larger pansy. Hybrids come in various colors, but usually revert back to the common purple and yellow color scheme over time. They are not weeds, and rarely dominate other plants, so enjoy their happy faces.

Starting

Location: In hotter areas, look for heat-resistant types and plant in moderate shade. Pansies can be planted in full sun where summers are cool. Seeds Indoors: Growing pansies from seed indoors can be a challenge. Sow indoors 14 to 16 weeks before the last frost date. Barely cover the seed, then refrigerate for 2 weeks. Once exposed to room temperatures, seeds should sprout in 10 days.

Basil and Beyond

Transplanting: Set pansies out in early spring as soon as the ground can be worked, and again in early fall to bring the gardening season to a colorful close. In warmer climates, set them out in fall for early spring bloom.

Watering: Weekly, 2 cups per plant. Water more often if the plants wilt and in the heat of the summer.

Maintenance: Keep pansies cool and moist. Deadhead pansies for continuous bloom, and cut back leggy plants to stimulate new growth.

How: Pansies make a cute cut flower keep in mind that the stems are quite short.

When: Cut pansy flowers just after they unfurl.


Plan for Maximum Harvest

If you plan to minimize the footprint of your garden yet maximize your production, you’ll want to calculate when your squares will be ready to harvest. This is sometimes a range of time indicated by the basket in the chart. Then you can mix a trowel of compost into that harvested square and be ready for the next season’s crop. This is an advanced skill and best planned in the winter if you plan to grow by seed. However, if you have access to summer transplants, you can certainly do this now.

Sample from All New Square Foot Gardening, 3rd edition. Full chart is in the book!


Herb Spacing:


Basil: 1 large per sq ft or 4 small per sq ft


Learn the basics of planning a square-foot garden ( SFG )—which makes efficient use of small spaces by densely planting in squares. Find out the pros and cons, whether square-foot gardening really works, the ideal size and depth that a square-foot garden should be, and more tips. Plus, find six SFG garden plans to reference.

What Is Square-Foot Gardening?

Square-foot gardening ( SFG ) is a type of raised-bed gardening—basically, a raised box divided into squares. With the square-foot gardening method, you plant in 4x4-foot blocks instead of traditional rows. Different crops are planted in different blocks according to their size for example, 16 radishes in one square foot, or just one cabbage per square foot. A lattice is laid across the top to clearly separate each square foot.

This planting method was developed by American author and TV presenter Mel Bartholomew in the 1970s. It’s a simple way to create easy-to-manage gardens with raised beds that need a minimum of time spent maintaining them. SFG advocates claim it produces more, uses less soil and water, and takes much less time to maintain than a traditional garden.

Mel Bartholomew had just retired as an engineer and decided to take up gardening as a hobby. It was only natural that he would apply his analytical skills to the problems he encountered. In particular, he found the average gardener was spending hours weeding the big gaps between long rows of plants, creating unnecessary work for themselves. It soon became clear that getting rid of rows and using intensive deep-beds could dramatically cut the amount of maintenance the garden required. Add a one-foot square grid on top and it became easy to space and rotate crops.

What Size Is a Square-Foot Garden Bed?

  • Typically, SFG beds are at least 4 feet by 4 feet, with a square foot lattice placed on top to visually separate the crops. That said, the beds can be 2x 2 feet or 4x12 feet, but the most common is 4x4 feet. This allows plants to be situated more closely together.
  • To keep the planting simple, there are no plant spacings to remember. Instead, each square has either 1, 4, 9, or 16 plants in it depending on the size of the plant—easy to position in each square by making a smaller grid in the soil with your fingers. As an exception to this, there are a few larger plants that span two squares. Climbing peas and beans are planted in two mini-rows of 4 per square.

How Deep Is a Square-Foot Garden Bed?

  • Beds should be deep—between 6 and 12 inches in depth in order to give plants plenty of rich nutrients, while still maintaining good drainage.

Other Square-Foot Gardening Rules

  • A specific soil mix, which is water-retentive and nutrient-rich, is used to fill the beds. This provides a weed-free start as well as being water retentive and full of nutrients. The rich soil enables plants to be grown much more closely than normal, which in turn crowds out weeds.
  • Thin with Scissors: Instead of pulling up excess plants (which can disturb the root systems of the plants you want to grow), snip them off with scissors.
  • Never walk on the soil in the bed, as this will only compact the soil. Back in the 1970s, this was a revolutionary idea!



Pros to Square-Foot Gardening

The “pros” for SFG are primarily ease and simplicity. SFG is a great method for new gardeners, people who have little time, the elderly or disabled ( SFG gardens can be built at a raised height to make them more accessible), and children. Many schools have embraced the SFG method because it’s easy to install and maintain without becoming an additional burden for the teacher.

Cons to Square-Foot Gardening

  • Although many vegetables can be grown in SFG gardens, it struggles to accommodate larger plants (squash, melons, main-crop potatoes etc), perennials (globe artichokes, rhubarb), and fruit bushes/trees. Once new gardeners experience the success of SFG gardens, they often want to expand the range of crops they grow beyond the standard SFG crops.
  • Originally, a soil mixture of peat moss, vermiculite, and compost (“Mel’s Mix”) was recommended in SFG . While this makes an excellent soil for vegetables, two of the three ingredients come from non-renewable sources. Peat takes thousands of years to develop and is a valuable natural sink for greenhouse gases. Vermiculite is mined and is therefore also a non-renewable resource with a significant carbon footprint. In common with many gardeners, we have moved toward using coconut coir instead of peat or vermiculite.
  • The specific soil mix and raised beds can be more expensive to set up than alternative methods, even though SFG is easier to maintain.

None of these reasons prevent SFG from being a useful part of a garden, though! You can use 100% recycled compost in the beds instead of Mel’s Mix, gradually build up the number of SFG beds and combine it with areas of your garden which are set aside for fruit trees and larger crops. Many of the SFG techniques that were revolutionary in the 1980s are now commonly used for vegetable gardening: deep raised beds, not compacting soil, removable covers and plant supports, etc.

Does Square-Foot Gardening Work?

Yes, square-foot gardening works for those who have limited space because it allows plants to be situated more closely together. Also, we have definitely found that there is less weeding. If you don’t have a lot of time available to weed, water, and maintain your vegetable garden, then square-foot gardening could be the answer. Finally, SFG has the benefits of all raised beds in that the soil warms more quickly for earlier planting and harvest.

However, there are limitations in what you can grow. As said above, plants that need more space such as corn, potatoes, watermelon, and pumpkins do not fare as well in boxes.

Square-foot gardening was revolutionary when it was first invented and it’s still a great system for people who are starting out, have limited space, or want a highly organized method to follow. However, you don’t need to follow SFG to benefit from gardening with raised beds and good organization. There’s a great quote: “If the only tool you have is a hammer, you tend to see every problem as a nail.”

SFG works really well for many situations, but it doesn’t fit everything. The success it brings can often lead people on to discovering the delights of fruit trees, using barrels to grow huge crops of potatoes, or managing a greenhouse full of high-value crops. It’s a great stepping-stone to the world of growing your own food and that’s why it’s still going strong 35 years later!

Video: See How to Set Up Your Square-Foot Garden

In this video, we introduce the thinking behind Square-Foot Gardening and explain everything you need to know to setup your own SFG garden beds including the best soil mix, plant spacing, positioning, companion planting and supporting structures to use.

Square-Foot Garden Plans

All of the SFG garden plans below were shared by Almanac readers!

1. Square-Foot Garden for an Apartment

“I live in a small apartment in the city but have a nice sized patio and wanted to take advantage of my space. This application helped me do it! My patio is outlined because it’s a little bit funny-shaped but everything with in the brown lines fits! The small red area is my back door and the larger red area is a shrub that I can’t do much with.”

Garden Size: 18’ 7” x 15’ 11”
Garden Location: La Crosse, Wisconsin
Sun or Shade: Partial Shade
Garden Soil Type: Poor Soil

2. Square-Foot Garden for a Home Garden

“This is my ‘chef’s garden’ with lots of different veggies and fruit that we like to eat.”

Garden Size: 19’ 11” x 19’ 11”
Garden Location: Denver, Colorado
Sun or Shade: Partial Shade
Garden Soil Type: Good Soil

3. Large-Scale SFG Garden

“Raised bed gardens with an emphasis on companion planting with the new tool. Soil is so-so but manure and compost and lime helped and will add more this year. Wondering about the problem of rotating crops next year but I hope the benefit of attracting beneficials will override that. I’ve got a three sisters garden (corn, beans and squash) and onions planted everywhere to help ward off pests. There are all the flowers that attract beneficials that I could fit in. I think it will take a lot of time to plant - but I am looking forward to it! Using the plant list now to organize my seed starts - Onions and leeks and shallots are up and waving! I have notes on seed starting on my plant list page. NOTE : Since I wrote this I have made changes due to the groundhog, primarily putting all the onion family and many herbs/flowers where he came in last year.”

Garden Size: 27’ 11” x 33’ 11”
Garden Location: Georgetown, MA 30x30 Town Garden Plot
Sun or Shade: Sunny
Garden Soil Type: So-So Soil

4. Square-Foot Garden Plan for Home Garden

“Organic garden planted in raised beds made using 4’ fence wire (bent w/1’ sides and 2’ bottom), lined with landscape cloth, then filled with soil made up of Black Gold (a special mix from a Nashville Nursery), worm compost, peat moss, coir, several different composts, mushroom compost and rock dust.”

Garden Size: 29’ 11” x 39’ 11”
Garden Location: Jamestown, TN
Sun or Shade: Partial Shade
Garden Soil Type: Good soil

5. Square-Foot Garden for a Front Yard

“Our front focal point garden will have a ring of strawberries and is planned to grow in a “cone” shape to tall sunflowers at the center.”

Garden Size: 19’ 11” x 19’ 11”
Garden Location: Indianapolis, IN
Sun or Shade: Partial Shade
Garden Soil Type: Good soil

6. Square-Foot Garden for a Front Yard

“Organic Vegetable Garden - Some traditional left but moving toward all square foot garden. Heavy clay soil amended for 3 years with horse manure, leaf humus, household compost, sand, wood chips, fish and organic fertilizer (includes chicken manure and minerals). Soil in square foot gardens according to Mel’s mix.”

Garden Size: 30’ 11” x 34’ 9”
Garden Location: Cleveland, Ohio near Lake Erie
Sun or Shade: Sunny
Garden Soil Type: Good soil, organic

See full plant list and more details about this garden here.

Square-Foot Garden Planner

Our online garden planner tool offers an SFG mode that makes it easy to add one-foot squares of plants as well as using all the other powerful features of the software such as crop rotation, tracking varieties etc. Best of all is that the SFG plants can be part of a larger garden plan that includes more traditional planting layouts and large plants, so there’s the flexibility to combine different methods in a plan of a single garden area.

If you need help designing your vegetable garden, try our Vegetable Garden Planner. We’re offering a free 7-day trial—ample time to play around and plan your first garden! We hope this software works for you.


How do I know how many seeds or plants to put in each square?

Now for the fun part – adding plants to your square foot garden. To calculate how many plants or seeds to plant per square, look at the back of your seed packet. Ignore the space between rows, but pay attention to how much space is needed between plants.

3″ plant spacing = plant 16 in each square.

4″ plant spacing = plant 9 in each square.

6″ plant spacing = plant 4 in each square.

12″ plant spacing = plant 1 in each square.

Some plants (such as melons, large squash, and tomatoes) require more than one square.

Use this tool to space seeds perfectly in your square foot garden.



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