Square Foot Gardening
Written by: Hamish
Published: 20th December 2018
Square Foot Gardening
Occasionally we get asked the question: “What can you do with a square foot of land?”
That question is the inspiration behind this article on Square Foot Gardening.
Here you will discover exactly what square foot gardening entails. We will explore this method of gardening, look into the pros and cons of such a system, and delve into the details of planning and creating such a garden step by step.
Intrigued? Read on to learn more.
What is Square Foot Gardening?
The phrase ‘square foot gardening’ was coined by Mel Bartholomew in his book of the same name, published in 1981. A retired engineer, Bartholomew brought his orderly mind to bear on the oft chaotic world of kitchen gardens.
He designed a ‘square foot gardening’ system in which more food could be grown in less space.
In this system, raised beds that are 4ft square are created. These beds are then separated into sixteen one foot squares, forming a grid. Each of the squares is then planted with a different crop. The number of plants in each square depending on the size and requirements of the crop planted in each.
Once each square foot is harvested, another, different crop can be planted within it, allowing for a continual harvest.
In 2006, Bartholomew updated the concept of square foot gardening in his book, ‘All New Square Foot Gardening’. In this book, he advocated the creating of raised beds just 6 inches in depth, filled with a mix of equal parts compost, peat moss and vermiculite.
After extensive research, he concluded that tweaking the original system in this way gave the best results. This method also eliminated the need for artificial fertilisers, since each square is replenished with compost each time a square is replanted.
The Pros & Cons of Square Foot Gardening
Like almost any gardening system that has been developed over the years, square foot gardening has both pros and cons. In order to determine whether square foot gardening (or some elements thereof) are right for you, it is important to examine these pros and cons in relation to your own garden, gardening style, preferences and requirements.
The pros of square foot gardening:
- Square foot gardening can give high yields in small spaces – far more food can be grown in this way than can be grown in a comparable space given over to traditional rows.
- Growing a variety of different crops close together is a form of companion planting, which increases biodiversity and helps to reduce the threat posed by pests and disease.
- Intensive planting minimises bare soil and acts like a cover crop to protect the important soil ecosystem that lies below.
- Closely planted crops also help to minimise the number of weeds that germinate and establish in the beds.
- The neat, raised beds of square foot gardening make it easier to garden if you are getting on in years or have mobility problems.
- The orderly nature of the system also makes it easier to stay on top of things and create a good plan for the whole of the gardening year.
- The soil-free growing mix proposed by Bartholomew further reduces weed problems and ensures high fertility in the raised beds.
- The raised beds and the garden system are easy to set up, even for complete beginners.
- The small beds are easier to cover with cloches, cages or cold frames to protect your plants than more sprawling and less intensively managed beds.
The cons of square foot gardening:
- The small beds are not ideal for crops that take up a lot of space such as pumpkins and squash, sweet corn or perennials like asparagus. (Though these can be grown elsewhere in your garden, leaving the square foot garden beds for annual vegetables with a more compact growing habit.)
- If placed above hardstanding rather than lawn or soil, 6 inch beds as suggested in Bartholomew’s 2006 book will be too shallow for the roots of many crops. (If raised beds are on a solid surface, they should be at least 12 inches deep.)
- The growing mix described in this book is, unfortunately, undesirable from a sustainability and eco-friendly point of view. Peat moss is not usually sourced sustainably, and vermiculite also comes at a high carbon cost. (Fortunately, greener alternative options for filling your square foot beds are available. These will be discussed in more depth below.)
- Square foot beds (like all raised beds) require more water, as they will dry out more quickly than in in-ground growing growing areas.
- While fewer weeds develop in square foot gardens, those that do establish are harder and more time consuming to remove, as you will have to weed little and often, by hand, rather than going between traditional rows with a hoe.
It is important to remember, when setting up a new growing area in your garden, that you do not need to follow one system religiously. While there are many things to recommend a square foot garden, it may not be right for you.
Some elements of the system may work for you while others need to be changed or adjusted to suit your individual needs. Be open to altering the ideas as you learn and garden, and you will end up with a garden that is best suited to you.
Planning a Square Foot Garden
The simple and methodical approach of square foot gardening makes it appealing to beginners, and easy for anyone to get started with. The first thing to decide is where to locate your new garden bed or beds.
Think about when and where sunlight enters your garden, which areas are in shade for which parts of the day throughout the year, the prevailing wind direction and how sheltered or exposed a potential location will be.
In a temperate climate, you will usually want to choose a spot that is as sunny and sheltered as possible, while shade may be desirable in hotter, drier climes.
Consider the location of other features in your garden – a compost heap, rainwater harvesting system or outside tap and perhaps the shed where tools are kept. Will it be quick and easy for you to move between these points?
Think also about how close your new raised bed should be to your home, and how visible it will be as you go about your daily life. A square foot garden requires regular visits and maintenance – the more easily you can reach it, and the more visible it is, the more likely you are to keep on top of things.
Creating Your Raised Square Foot Garden Bed
Once you have decided where to position your new square foot garden bed or beds, it is necessary to determine how large or small each one will be. As long as the beds are a whole number of square feet in length and width, and as long as you can easily reach each square on the grid without standing on the beds, you can make them as large or as small as you wish.
In a tiny space, you may only be able to accommodate a raised bed of 2ft by 4ft, for example, while in larger gardens you can create one or more larger beds with 16 or more square feet within them.
In larger gardens, it is usually better to have a number of smaller raised beds rather than one big one, as these will be easier to reach and tend, and will also maximise edge – the most productive part of any ecosystem.
What You Need
While there are a number of square foot garden kits that you can buy to make the edges of your raised beds, you can also consider keeping costs down by making your own.
There are a number of different materials that you could use – reclaimed wood from old pallets is a popular choice, though you could also use bricks, reclaimed concrete blocks, stones or even logs from your garden or from local woodland.
The grids to demarcate the squares on the surface of your raised beds can also be made from natural or reclaimed materials – bamboo canes, for example, straight branches pruned from garden trees, natural twine, or perhaps reclaimed plumbing pipes.
You may also, at this stage, wish to consider creating supports for climbing plants on one side of each bed, and may also like to consider frames over the beds to support netting to protect plants or covers to extend the growing season.
In order to stop grass and weeds from growing up through your raised beds, some people advocate the placement of a plastic weed membrane below each bed. A more sustainable and eco-friendly option is to suppress weeds below your new growing areas with a thick layer of cardboard.
Another benefit of this option is that the cardboard will break down over time and allow the roots of your crops to pass through into the soil below.
Filling Your Square Foot Garden Bed
Once you have created your raised square foot garden bed structures, it is time to fill them with your growing medium. You may choose to follow Bartholomew’s book to the letter and use a soil-free mix of peat moss, vermiculite and compost as he suggests.
If you would like a more eco-friendly and sustainable soil-free mix, you could consider using coconut coir as an alternative to peat moss and ‘pine fines’, finely ground pine bark, as an alternative for the water-retentive vermiculite.
You can buy your compost, but it is far more cost effective and sustainable to make your own. If you do not already make your own compost from vegetable scraps and other garden and kitchen waste, now is the time to get started. Make sure you have started your own composting system before you begin to plant, even if you have to buy in compost to get started.
The Lasagna Method
Another thing to consider is building up your raised beds for square foot gardening using the ‘lasagna’ method. This method involves, basically, composting materials not in a separate heap but in the raised beds themselves.
Create thin layers of ‘brown’ carbon rich material (such as straw, cardboard, brown leaves, chipped wood/ bark), and ‘green’ nitrogen rich materials (such as grass clippings and fruit and vegetable scraps). Build these up to the required height and then top the beds up with a top layer of good quality compost.
Planting Your Square Foot Garden
As soon as the requisite season arrives, you can start sowing or planting seedlings into your square foot beds. The key when planting is to make sure that you are placing the right number of each type of crop into each square foot of the garden. Here is a brief guide to the spacing requirements for many of the most common crops:
One Plant Per Square Foot
The largest plants that can easily be included in a square foot gardening system will require one whole square foot each. These include brassica such as cabbages, broccoli, Brussels sprouts & cauliflower, geraniums, tomatoes, peppers, aubergines and herbs such as coriander, rosemary, oregano, sage and mint.
Four Plants Per Square Foot
Some plants in this category could grow to full size if planted one per square foot, but can be more intensively planted if you harvest them as they grow, which will keep them in check.
These plants include leaf lettuce, chard, Swiss chard, parsley, basil and a number of other leafy greens. Dwarf marigolds, an incredibly useful companion plant, can also be spaced at four per square foot.
Nine Plants Per Square Foot
Crops in this category include bush beans, peas, beetroots, large turnips, parsnips, kohlrabi, bok choi and spinach. Each of your seeds or seedlings will be placed at four inches apart.
Sixteen Plants Per Square Foot
Carrots, radishes, onions, garlic and spring onions are all examples of plants that can be grown intensively at a spacing of 3 inches, in blocks of four by four.
When planning your planting scheme, take into account how much of each crop you wish to grow and the requirements of your own household. You will also need to consider the requirements of the plants in question, and whether each crop you choose will do well when planted next to its neighbours.
Companion planting is an inexact science and we know surprisingly little about how different plants interact with one another. That said, it is clear that plants with similar requirements will do well when grouped together.
For example, it is best not to place Mediterranean herbs, with their lower water requirements, next to especially thirsty plants that you will have to water often.
Similarly, it is easy to see how certain plants can help others by improving their environment. For example – taller plants used to provide mid-summer shade for neighbouring spinach or lettuce, helping reduce the risk that it will bolt in hot weather.
Some plants can help those in neighbouring squares by gathering nutrients. Dynamic accumulators such as peas and beans fix nitrogen from the air, while deep rooted plants like borage or yarrow can reach right down deep into the soil below your raised bed and bring nutrients back up. When leaves from these plants are used as a mulch around your crops, those nutrients are returned to the soil surface where they can then be taken up by neighbouring plants.
Other plants can help reduce the incidence of pests or disease in their neighbours. Marigolds are a useful ‘nurse’ plant to place throughout your square foot garden. Aromatic herbs and flowers can often help neighbours by repelling certain pests, or attracting their predators. Some also act as sacrificial trap crops, keeping pests away from neighbouring plants.
Thinking about companion planting can help you to design square foot garden beds with beneficial mixtures of plants which can aid one another and create healthy, diverse eco-systems. These collections of plants are sometimes called polycultures.
Another thing to think about when planning and planting your new growing areas is that certain plants should not be grown in the same location year after year. Certain plant families, such as brassicas, and the nightshade family (potatoes, tomatoes, peppers etc…) should be rotated between different square feet/ beds on a three or four year cycle.
Legumes such as peas and beans are also rotated, to allow them to provide nitrogen to different areas of the garden, and are usually followed by a nitrogen-hungry, leafy crop. To keep things simple, square foot gardeners often choose to have three or four beds in their gardens, so they can practice crop rotation for those crops for which it is important.
Maintaining Your Square Foot Garden
In a square foot garden, there is an emphasis on making the most of time as well as space. Bare soil is kept to a minimum and as soon as one crop is harvested, another one will take its place. This intensive use of the growing area means that it is vitally important to make sure that you replenish the nutrients that have been used and maintain the fertility of your garden.
Adding compost each time you harvest a square, and adding mulches of compost or other organic materials between plants can help to make sure soil health is maintained over time. You can also make organic liquid feeds from compost, weeds etc. to give hungry plants a boost without harming wildlife or the planet.
As well as maintaining fertility, square foot gardeners will have to keep on top of weeds, weeding little yet often, and water the raised beds well during any dry spells. They will have to keep an eye out for pests and disease, and harvest on an ongoing basis throughout the growing season.
Take care of your square foot garden and it will continue to take care of you, feeding you and your family now and in the years to come.