Square Metre Gardening or SMG for short

I know I have touched briefly on this subject before when describing the set up of my own garden but the more I do it, the more I feel it is worthy to share! I will give a summary of the where, what, and how, here but you really need to get his book for the finer detail if you are going to do this. If I tried to write it all out here…..well, er…..it would be a book! (Affiliate link coming up) Not meaning to be pushy but this book really does have everything you need to know……..

 or to buy your copy click this link

Square Metre Gardening or SMG as it is known by its proponents (and sometimes as Square Foot Gardening or SFG) was brought to my attention in this book by Mel Bartholomew. In it he describes how he usually illustrates his point when giving a talk on the subject. ” How much ground do you need to feed a  family?” he asks, then divides the room in half, and half again and half again. In other words, whatever ground you think would need to grow veg for your family and more, with SMG you will only need roughly 20%. In other words, a traditional kitchen garden needs about 40 square metres to grow enough food for a family of four. But with an SMG system in place you would only need 20% of the space or 1/5th of the ground.

How does SMG work?

Square Metre Gardening Raised Vegetable beds

The principle of Square Metre Gardening is to grow what you need on a successional planting/harvesting basis, inter-planting when and where possible. This is achieved using square metre raised boxes. You can make your boxes as high as you like, mine are 50cms high but 15cms is fine. Each box frame is then divided into 9 equal squares so you no longer plant in rows but squares.  Whilst the saying

One for the blackbird, One for the mouse, One for the rabbit and One for the house 

is a charming ditty prompting the amount of seed to sow, with the intense planting of SMG, you only plant what you will actually need. Sowing and harvesting through the season means continual harvest for as long as your growing season allows. And it avoids the gluts and the burden of what to do with all those veggies, when everyone else is groaning under their harvest too! It is also a “No digging needed” system. You never have to dig the ground, not to set it up, not even each year.  You continually top up the growing medium each time you harvest giving your veggies a nice fluffy bed to grow in!

What you need to do

It does take a bit of time and effort to set up your productive garden using this method but it saves time in the long run. In his book Mel Bartholomew gives the example of a family of four needing approx 1 square metre of salad each person and the same for Supper vegetables, and if they want vegetables for preserving, another square metre box. Or if you prefer, 3 x 1 metre box of salads will feed a family of four for the season.

Raised Veg bed with divisions in place for SMG
Raised SMG bed with wooden dividers in place. (The upright pipes are for netting support)

To work out what we would need for us here at Dovewood, I wrote down all the vegetables (and fruit) I wanted to grow. I then calculated roughly how much I think we use in a year. This wasn’t difficult as one of us – ahem, mentioning no names – doesn’t like salads or many varieties of veg! Using the charts within Mel’s book I checked how many plants I could get in each square within the box and what the likely harvest would be from each plant. From this I was able to calculate how many plants I would need to grow to achieve the harvest I want. For example, we use one head of cauliflower every couple of weeks so 52 weeks ÷ 2 = 26 plants would be needed. I then discovered I could get seed for a variety that produces 4 small heads per plant. As you need one square (30cms) per plant I am planting 6 squares which should give me 24 heads of Cauliflower.

I hope that doesn’t sound too complicated because it really isn’t, and once you’ve done this bit it makes setting up your boxes so much easier. For me, unless a certain member of the household changes his diet, the plan should roll from one year to the next. The only adjustments needed will be if I haven’t got my anticipated harvest quantities right!

Growing Potatoes in sacks

As Potatoes take up a far amount of space I decided that I would grow them in sacks rather than take up valuable bed space and you can read about  how I did that here 

Creating your SMG Beds

As for actually building your beds, there are kits available or you can build your own raised beds out of whatever material you have to hand or can buy. The book gives clear instructions on how to make a timber bed. One word of warning though, if you use treated wood as we have done here, you will need to line the beds (we used surplus pond liner on the inside) to prevent any chemicals leaching into the compost and ultimately into your vegetables.

Raised SMG beds ready for planting

As the only available ground at Dovewood is a rather narrow strip it meant adjusting the shape of my beds to suit. I ended up with two beds approx. 2.4 metres long and 1.2 metres wide. Yes, I know, not one-metre-square-boxes but such is life! The important thing is I can divide them up into squares and apply the principle of SMG. And to make them aesthetically pleasing, the opposing end of each nearest the central path is split level, as it can be seen from the lawn and leads to a focal point of the garden – more on that another time!

Once you have decided how many beds you need, and built them, the next task is to fill them with compost/growing medium. Mel Bartholomew is very specific about this – any old soil just won’t do. As you will be planting crops closely  – remember no rows, no conventional spacing – your precious plants will need to be growing in good healthy stuff. He gives his “MelMix recipe” in his book the formula of which is

1/3 Garden compost

1/3 Peat Moss or Coir

1/3 Vermiculite

NOTE if you haven’t any garden compost available buy bags of general purpose compost but get it from several suppliers to get a good range of compost material

Shock horror at the mention of Peat? Well this is a one-off time to buy in and you can get some from a company that harvests peat from drain water. If your conscience doesn’t allow any Peat, then use Coir – as I have – that is fine as an alternative. Vermiculite is preferable but you can use Perlite. I don’t like it as it just doesn’t look as nice, with all those white blobs in the soil.

After the initial set up, all you will need is home-made compost. You do have a Compost bin, right? You are making it aren’t you?!

Each time you harvest a ‘square’ you add back a spoonful of compost to replenish the plot with nutrients. Easy!

Square Metre gardening harvest

A Difference of opinion!

Mel helpfully explains how to work out the quantities of each compost component that you will need for each Square Metre Garden bed.

There is one point I do disagree with him.

If you are making the beds deep like ours Mr Bartholomew suggests filling the base up with gravel! Aargh! No Way! Mel’s Mix is quite free draining  and putting 15cms of compost over the top would be like putting it in a sieve, all the water will drain straight through, if not just wash down into the gravel. Besides if you want to grow full length carrots or parsnips you need greater depth than 15cms! They hate stoney soil. If you must use gravel to fill up the base of a deep bed cover it with a membrane or water-retentive material (punctured with drain holes) to retain the growing medium which need to be deeper than 15cms for deep growing vegetables. We opted for using some spare top soil for the lower half of each of our beds, and used the Mel Mix for the top half. I admit this was quite expensive as I used:-

700 litres of Coir (10 x 70lt Bricks of compressed and dehydrated Coir which we then soaked – one brick to a wheelbarrow full of water!)

10 x 70 litre bags of general purpose compost bought from three different suppliers

600 litres of Horticultural Vermiculite which I bought on eBay

Mel Mix SMG compost mixed by foot

The best way to mix these is to tip them onto a large plastic sheet, or as we did, onto a tarpaulin. Only mix as much as you can handle in one go. I did it by scuffing up and down in my wellies – which has to be the best work-out ever!

Once the beds were filled and levelled, my husband made a grid of timber using Roofing lathes. You could use anything to make the dividers such as: String and drawing pins, curtain rods, or metal poles. The important thing is to divide your boxes up. It might look nerdy but it is really helpful when it comes to planting the individual squares as you can actually see them. It also creates a conversation starter when showing friends around your new kitchen garden!

Planting time – help is at hand

Planting in Square Metre Garden

This is the really fun part when you finally get to start your crops. You’ve bought the seed,  you’ve got your baby plants, you head to the garden and……

If you are anything like me you can’t remember how many plants go in each square! The planting distances on the back of the seed packet will probably only have the traditional spacings written on them.You will need to look each variety up but if you are a veg growing newbie how on earth are you going to remember that cauliflowers belong to the Brassica family or which family will you find sweetcorn in? Sorry Mel, you’ve lost me there! I need a quick planting reference…….

Planting Distances

To solve this problem, I have made a Veg Planting Distances cheat sheet which I have laminated and I take it into the garden each time I am planting. For ease of use it is arranged alphabetically, by the common names of each vegetable, (rather than by plant family names), and has the number of plants per square alongside. Such a help. So if you would to get one for yourself, you can get it here…….



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2 thoughts on “Square Metre Gardening or SMG for short

  1. I began my veg plot this way and I think it’s a great way to start. It enables you to try lots of different things and then, in time, you home in on what you really eat and want to grow going forward.

    • Helen Cronin

      Thanks for your comment. So glad you enjoy the benefits of Square Metre Gardening too!

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