Green City Gardens

During 2017 I took part in a research project being conducted by staff at University of Sheffield, under the banner of MY Harvest, into the impact of home grown produce on UK food production.  The project involved enlisting domestic gardeners who grow their own fruit and vegetables, either on an allotment or at home, to submit data about their crop yields throughout the year.  This blog post is about what the data for my own plot has revealed about this year’s harvest and has been written in conjunction with Datawoj (otherwise known as my husband!) who did some snazzy data visualisation for me.

The MY Harvest Project

The MY Harvest project is focussed on recording data for 25 of the most popular home grown crops such as potatoes, salad crops and soft fruit.  Participants were asked to submit data via the website on the space used to grow named crops and the yield in kilograms each time the crops were harvested throughout the season.  The project team have produced an infographic summarising the findings from the first year of the project.  The website also allows participants to download their own data which has been used for this blog.

I submitted data for 15 different crops.  There were other crops such as Rhubarb and Swiss Chard which are not included in the 25 selected for the project which had good yields, and equally there are crops such as Parsnips and Brussels Sprouts which we grew but have not yet submitted data on.

Factors which can effect the harvest

A number of aspects can effect the harvest of different crops including:

• Weather – in 2017 the Spring and early Summer were dry and warm while mid to late Summer was much wetter.  This worked well for some crops but not for others e.g. courgettes were disappointing perhaps due to the wet weather later on.
• Pests – in 2017 I tried using nematodes for the first time in an effort to reduce the impact of slug damage.  This worked well in terms of allowing seedlings to establish but with only one application and wet weather later in the season the slugs fought back.  Other issues included bird damage to crops such as turnips which were not netted initially.
• Crop variety – I like to grow different cultivars of crops and rotate these every couple of years.  Some inevitably perform better than others depending on the conditions in which they are grown so this can be a factor in overall yield from one year to the next.  *Details of the cultivars grown in 2017 can be found at the end of this blog.
• Timing – planting crops at the right time of year and also planning for succession sowing can influence the overall yield for individual crops.  Planting too early or too late can result in crop failure.  In 2017 I mostly got this right with the exception of the later stages of the season (putting paid to the Kale and Broccoli) for the reasons given below …
• Time – how much time you have to spend tending to your plot can influence yield in terms of pest control, weeding, succession planting etc.  An issue for me particular to 2017 was that I was pregnant for the whole growing season, which meant that I was physically unable to devote as much effort as I normally would in August/September, and this may have influenced the harvest later on.

What the data tells us

The data extracted from MY Harvest relates to the space allocated to each crop and its yield.  In addition I thought it would be interesting to look at crop values in relation to their sale price in the supermarket at the time of harvesting and have therefore added this into the data set.  The following charts represent different aspects of this data including space used, yield and value for different crops.

Some insights arising from the data include:

• Potatoes are a high yield crop by weight, particularly the maincrop potatoes.  However, they are fairly low value in relation to the space they occupy.  That said the fact that maincrop potatoes can be stored over winter adds to their usefulness and so if space is restricted maincrop varieties may be the best option.
• I grew waaaay too many Runner Beans!  I don’t really need the data to know this – the stacks of beans still in the freezer are enough of a reminder!  That said Runner Beans are a high yield, high value crop and occupy relatively little space and so are good option if you like them.
• Although Squash occupy a fairly large amount of space they produce good yields by weight, are fairly high value and, like potatoes, can be stored over winter.  Plus they often look great!
• Soft Fruit including Strawberries, Gooseberries, Redcurrants and Blackcurrants are very good value crops for the space required.  I grow the Gooseberries and Redcurrants as cordons which take up very little ground space.  They are also not always readily available in the shops so a good choice for grow your own.
• Summer Cabbage occupied a large area for the yield.  Cabbages in particular I find are prone to slug damage and without adequate storage space are difficult to harvest quickly enough to avoid the most severe attacks.  They do not appear in the value charts as they were priced per item rather than by kg but are also a low value crop at less than £1 per cabbage.
• Sugar Snaps performed particularly poorly.  I have grown these for two years and in neither season did they produce good yields.
• Courgettes and Broad Beans are normally reliable performers but were disappointing in 2017.  In another year I would expect these to appear higher up in the yield charts.
• Beetroot is a reliable cropper, requires little space and is relatively high value so definitely one to include if you like it.

In Conclusion …

Sugar Snaps are certainly off my agenda for 2018 and, in light of this analysis, I am considering either significantly reducing the space given to Summer Cabbage or abandoning it altogether.  After the overwhelming mega-glut of Runner Beans in 2017, I am going to grow a different type of climbing bean in 2018, but will certainly return to them again in future.

My motivation for having an allotment is very much more about growing for pleasure, health and well-being, but if financial considerations were to the fore I would certainly focus on fruit along with crops such as Squash, which provide high value for the space required.  Potatoes are perhaps less of a necessity in this respect but freshly dug potatoes are a lovely thing to have access to, and maincrop potatoes have additional value in terms of their suitability for storage.

The MY Harvest project is set to continue through 2018 so it will be interesting to see how next year’s data compares to that for 2017.  In addition to continuing data collection, volunteers are being sought to keep a journal for 12 months about the time they spend on the allotment, materials used, activities performed and wildlife encountered to build up further detail about the impact of grow your own, and this is something I have already started doing.  Looking forward to the 2018 season to come!

*2017 Cultivars

Crop	Cultivar
Beetroot	Boldor F1
Blackcurrants	Ben Sarek
Broad Beans	Masterpiece Green Longpod
Carrots	Mixed
Courgettes	Atena Polka F1
Summer Cabbage	Golden Acre (Primo II)
Gooseberries	Invicta
Potatoes (Early)	Duke of York
Potatoes (Maincrop)	Stemster
Redcurrants	Laxton’s Number One
Runner Beans	Firestorm
Squash	Crown Prince
Strawberries	Unknown
Sugar Snaps	Sugar Ann
Turnip	Milan Purple Top