Container growing - what's the cost?

How much does it cost in time and money to create a high yielding vertical allotment? I estimate it will cost me £190 and 170 hours this year to build and run my balcony and window sill allotment. Assuming I harvest £800 food over the year, this means that, after costs, I ‘earn’ £3.60 for every hour worked. Well below the minimum wage – but not bad to get any return at all for a hobby I love! If food prices rise as predicted in the future, it will be interesting to see how these figures change.

Do you need to spend this much to recreate a project like this? The answer is that it depends.  With a bit of time, a few DIY skills and a keen eye on local skips, you could build one for less (just a few pounds) in London.  You can also get free municipal compost, save your own seeds and / or attend seed swaps to get seeds for free or for very little. Alternatively, if you buy it all from a garden centre, you'll spend a lot, lot more!

If you’re just starting out, I'd recommend creating a vertical allotment step by step, adding a few containers each year. In this way, you'll learn as you go and spread the work load as well as the cost.

It’s not just about money, of course. The other benefits are why I do it. Top of the list is the simple pleasure of growing and eating fresher food than you can buy, as well as varieties which you rarely see in the shops. Then there’s the satisfaction of cutting food miles, re-using waste resources, and striking up new and unexpected conversations with neighbours and passers-by intrigued by the pots of towering sweetcorn and the trailing squash growing by our front door.

Using old floor boards, plastic boxes, estate agent posts and pvc drainage pipe to make containers with water reservoirs

The Costs

In the table below I’ve estimated the total spend, the number of years I think each item will last for, and then worked out the average cost per year. Some of the figures have been harder to work out than others. For example, I've sourced the growing mix from many different places over several years, some bought and some free. My containers hold 1600 litres of compost, equivalent to twenty-three 60 litre bags. So I've estimated an average cost of £7 a 60 litre bag, which works out at £160 in total.

I've spent significantly more than I need to. I bought a worm bin before Camden Council started to subsidise them and before I learnt how easy they are to make yourself. I buy many more seeds and plants than I need as I'm constantly experimenting to find out what grows best  (two blueberry plants alone set me back about £30 this year). And I spent £70 on  plumbing bits for a self watering system (in picture) which isn't  strictly necessary but does save time.

	Total £	Est no. years	Cost / year
Seeds and plants	176	2	88
Containers
Osmo wood protection oil	24	4	6
Screws	6	4	1.5
Wood from skips	0	4	0
Pondliner	8	4	2
Recycled plastic containers x 11	0	5	0
Plastic containers x 9	18	5	3.6
Earthbox x 1	32	10	3.2
Large plastic container x 1	8	5	1.6
Shelves & platforms
12m reclaimed 2 x2	12	4	3
Wood preserver	8	4	2
Water butt, recylced olive barrel	23.5	10	2.35
Plumbing for self watering	70	10	7
Guttering & downpipe extensions	34	10	3.4
Compost - growing media	160	5	32
Fertiliser
Chicken manure pellets	5	3	1.66
Seaweed fertiliser liquid	6	1	6
Comfrey & nettle leaves	0		0
Wormery	140	5	28
Worm compost	0	1	0
Totals	£730.5		£191.31

The Time

The containers, shelves and watering system took 12 days to build. Working with wood reclaimed from skips is slow but ultimately satisfying. The wooden shelves and wooden containers took the longest time.    You could cut the work considerably by using ready made containers and buying brackets for shelves. This way, I reckon you could construct a high yielding allotment in a weekend or two.

On top of this, I spend an average of 1 day each  month sowing, planting, tieing up etc - most often as two or three sessions of 2-3 hours. I also spend 15 minutes every day in spring, summer and early autumn watering and keeping an eye on the crops. Daily attention is key to a productive container garden. Luckily I also find this part the most rewarding - watching the plants grow, observing the toing and froing of wildlife, and harvesting the crops.

The total time spent on my vertical allotment per year = 3 days or 24 hours construction (assuming the current structure lasts four years) + 12 days or 96 hours sowing and planting + 50 hours watering and observing (based on 15 minutes a day for 200 days) = 170 hours.

"Profit"

Assuming I grow £800 of food over the year, the surplus after the costs of £191 = £609. This equates to £3.60 per hour worked, well below the minimum wage.

This highlights what we already knew: growing food at home is a hobby rather than a potential business or livelihood. But it will be interesing to see how this equation changes when food prices rise as predicted in the future.

Comparison with Allotments

A survey in 2008 / 2009 found that allotment holders spent an average of £202 a year, and worked 203 hours to maintain a 300 square yard plot. The average yield worked out as nearly double mine at £1564 a year.  Based on my figures, this shows that an allotment produces double the return per hour invested. However, these figures don't take into account the time spent travelling to an allotment (significant in some areas) or the benefits of having food growing at home and being able to harvest it just as you need it.