Square Foot Gardening Looks Productive, Easy and Sustainable. But Is It? Here Are The Pros & Cons Over No-Dig & Traditional Gardening Techniques
Square Foot Gardening is the gardening technique where the growing bed is divided up in small, orderly subdivisions where individual, or small numbers of plants can be grown.
It was invented by retired engineer Mel Bartholomew in the 1970s and attracted amateur gardeners in the USA and beyond in the 1980s after the first Square Foot Gardening book was published.
Square Foot Gardening (SFG) claims to use 20% less space & 10% of the water, cost 50% less, and only 2% of the work compared to single-row gardening. Claims are also made that it does away with the need for pathways, reduces weeds and does away with the need to dig.
My observations are that some of these claims are certainly justified, and it has the merit of introducing many people to gardening for the first time, but I believe other methods can also match some of these claims. I also have concerns over the sustainability of SFG and its environmental credentials.
Square Foot Gardening: An Introduction
SFG is the practice of dividing the veg garden up into small manageable units that each produces a recommended number of plants. The typically recommended garden comprises a series of 6 inch deep raised beds filled with a recommended growing medium typically made from moss peat, vermiculite and blended organic compost.
Each bed typically measures 4 foot by 4 foot and are then subdivided into square foot units. Hence the typical bed comprises 16 square foot units. Beds can be joined to make units measuring 4×8, 4×12 or longer with pathways between them.
The following video shows typical layouts and cropping and was produced to celebrate SFG Day 2020. It’s quite inspiring but does demonstrate some of the problems that SFG presents gardeners.
Plant Spacing in the Square Foot Garden
As the video indicates plants are laid out in a grid formed by dividers that sit on the beds. The recommended size of each grid is one square foot ie 12 inches by 12 inches. The problem is that nature hasn’t designed plants to fit these grids.
For example an outdoor bush tomato planted n the centre square of a 4×4 bed could easily grow to cover the whole bed. And trying to keep it within the bounds of one square is going to severely limit growth and yield.
Ditto crops such as marrows, courgettes, butternut squash and pumpkins. They all need much more space.
The recommendation for growing carrots is top put 16 in a square foot section. How you germinate and grow 16 evenly spaced carrots isn’t explained on the website (though there are ebooks and videos that can be purchased). It might be possible if we grow each in an individual plug but this seems rather labour intensive for a system that claims to only require 2% of the time conventional methods require.
The other problem with carrots is that many varieties need a greater depth of growing medium than that offered by the recommended 6 inch deep bed. The same applies to parsnips.
My experience of trying SFG is that crops such as leaf lettuce are well suited to SFG if you just scatter the seed and don’t abide by the recommendation to grow just six plants in each square. Ditto many herb crops.
As for brassicas, many require more than a square foot to get to a decent size.
SFG recommended plant spacing can be seen by following this link. In some cases, they recommend up to 72 plants in a 4×4 bed. As a retired commercial grower, this seems complex and tedious to follow and I’m not convinced that it will maximise yields as far as other techniques with which I’m familiar.
SFG Raised Beds
Raised beds appeal to many gardeners and I can see the benefits of table high beds in reducing back strain on those of us that have back problems.
There is no doubt that raised beds can also look very pretty, indeed decorative in the garden. I’ve seen them with fancy paintwork and finials and I can see the attraction.
But this comes at a price. Not just the cost of the timber required to build them but also of the compost to fill them. The cost can be reduced if Hügelkultur is practised but then you need some big trees or tree stumps to put in the bottom of the beds.
The other problem with raised beds is that they provide perfect homes for slugs and other detrimental organisms, from earwigs to fungi.
I’ve also seen complaints about the need to replace beds after a few years as they rot in inclement weather conditions.
Finally, there’s the question of water. Anything raised above the soil level tends to dry out much faster than the soil itself. The sun bakes raised beds and the wind whistles around them, and both manage to draw moisture from the soil however carefully the beds might be lined with plastic.
SFG & Weeds
Because new com-ost is used from the outset I’ve no doubt that weed problems are minimal from the outset. However, weed seeds blow in, are carried in by birds and other animals and can come from any weeds left to seed. So the weed-free element could be short-lived unless firm control of weeding is maintained.
No-Dig offers the same weeding pros and cons so this situation is not unique to SFG.
SFG: Recommended Soil Mixes & Their Environmental Cost
Within the raised beds it’s recommended that a specific growing medium is used. This is comprised of :-
1/3 Coarse grade Vermiculite
1/3 Blended Organic Compost
1/3 Sphagnum Peat Moss (The recommended alternative is Coconut Coir)
Vermiculite is a natural product but has to be processed. It is mined and shipped around the world from mines in South Africa, China, Brazil and Russia. At some point in the process, it has to be heated to extremely high temperatures in furnaces, usually powered by natural gas. The environmental cost of mining, heating and transport is huge. Huge amounts of CO2 are produced in the mining, manufacture and shipping of vermiculite.
This I believe makes the use of vermiculite in such large quantities as a third of the growing medium very environmentally unfriendly and seems to go against the ethos of home-produced sustainable vegetables.
The use of sphagnum moss peat is also extremely questionable. Environmentalists have been warning against the use of peat for many years and it used far less commercially these days than it was previously. In some countries, it can be banned within a few years.
The reason it is not being used is that the public recognises the environmental damage that is done by ripping out peat from fragile ecosystems. Plants, insects and larger animals are destroyed in the process. It also releases huge quantities of CO2 that have been tied up in peat wetlands for centuries and CO2 is responsible for global warming.
So I don’t believe that this square foot gardening mix is sustainable or that anyone that cares about their environment would use it if they realised how bad it was.
Square Foot Gardening: The Financial Cost
Proponents of SFG claim it is low cost. I struggle with this as being factual when the cost of raised beds and the compost mix is considered. We are talking about hundreds of £s for a small to medium size garden before any seed is bought. How this can be 50% of the cost of conventional gardening or No-Dig gardening I’ve no idea and no one has managed to explain the reasons to me.
SFG: Time Considerations
It is claimed that SFG takes just 2% of the time that row cultivation takes. It can take less time perhaps, but I find 2% impossible to believe. And if it did I’d probably not enjoy my gardening nearly as much.
Certainly smaller areas, that are used intensively, can mean reduced labour requirement.
The efficient No-Dig garden is an alternative when time is the measure being used. No-Dig is very time efficient and doesn’t need additional time and expense.
Square Foot Gardening: Watering Frequency and Quantity
Raised beds readily drain and being raised they catch the wind and sun more than beds at ground level. And if the recommended compost dries out it can be very difficult to re-wet.
This means that the SFG gardener needs to be vigilant. They must never let the compost dry out or they will have various growing problems, from tomatoes with blossom end rot to split carrot and parsnip roots.
This means constant hand watering, overhead irrigation or a drip system is needed. This can be time-consuming, expensive or both.
At the very least a good layer of mulch will be needed to keep the compost moist. And though mulch is good for the garden it’s another time or money pit.
SFG: My Conclusions
Raised beds, whether for SFG or any other growing system can look good. And if the look of the garden is a very high priority then they make sense.
I’m sold on the idea that SFG has attracted many new gardeners and can see why the claimed certainty and promises are attractive. But I think the reality is often different from the claims.
One thing that worries me is the expensive growing medium, artificial soilless media is never going to be as good as soil used in a No-Dig garden. In No-Dig the soil is full of fungal hyphae that span the whole garden and beyond. The hyphae access moisture, nutrients and bacteria that drive a natural process. To me, SFG will grow crops but it’s heartless and the home of people that don’t really understand nature, sustainability and how plants tie mankind to nature in the way that others do.
If it were such a good system it would have been invented much longer ago than the 1970s and today it would be giving free advice on how to garden this way, not making it all about having to buy a book to learn more.
I’m not against books being sold, I sell books myself. But I also provide answers to any gardening question posed to me on my Facebook gardening group. And that will always be free.