This project is open
Updated purchase values
As of June 2022, the purchase values for crops in the calculator have been updated based on then-current prices. As a result, harvests may have increased their equivalent real-world value by 20-30% - so make sure you have the most recent version of the calculator!
How much does your garden grow?
Getting out in the garden is a great pastime. With the popularity of ‘growing your own’ on the rise again, many people are increasingly thinking about how to make their gardens and allotments more wildlife-friendly. There are lots of reasons to make space in your garden for wildlife, and this project looks into the help that those attracted animals provide to our own growing efforts:
Bees (and other pollinating insects) are needed for many of our garden favourites to produce a good harvest, but the impact of insect pollination varies by crop. E.g. Apples really need pollinators, since their pollen is heavy, doesn’t get wind-distributed well, and the flowers don’t fertilise themselves. Tomatoes can set fruits without insect help through wind disturbance and self-compatibility, but still produce a greater yield of fruit if well-pollinated by bees. On the other hand you mostly grow lettuce, or self-pollinating peas, then your garden bees won't have contributed much to the final salad!
The Garden Shop calculator is a simple spreadsheet that helps you to get an idea of:
How much your 'garden shop' (your harvest) would have cost you to buy in a supermarket.
What proportion of that is directly a result of insect pollination.
This gives you a clearer picture of how much your garden wildlife help out - and gives us a better understanding of how much UK gardening relies on insects, and how best to encourage people to make space for these important creatures in their green space.
Download it from the link below. There are instructions in the sheet on how to use it, as well as on this page.
Name: Garden shopping
Year(s): 2016 -
Focus? Pollination value
Results? Ongoing analysis
Project lead contact:
~£2300 of fruit & vegetables
(organic values). Insect pollination was 62%; ~£5000 'earned'!
Downloading the Garden Shop calculator
The calculator is free to download from the Buzz Club, from the links to the right,. It is an MS Excel xls. file, so is compatible with MS Office and Google Sheets (and likely any third-party software you use to read / edit xls. files, although it has not been tested out on others).
If you are unable to download the spreadsheet, please let us know, and we can send you a copy of the file, or a google sheets version just for you.
Or you can use the new printable recording sheet to track your harvests, and let us know later to get your calculations!
Please note that the file may open in ‘protected view’ when you’ve downloaded it – this is because it has come from an internet location. This can cause validation errors with newer versions of Office (see the Microsoft Support Page on these errors).
The file should be fine, although do give it a quick scan with your virus-checker if you’re uncertain!
Save it to your computer to get rid of the error.
You might get one of these warnings at the top of your page, because this is a downloaded file.
Using the Garden Shop calculator
To use the calculator, you will need to record how much you have grown of each crop type. This can be by weight (in grams or ounces); by number of things (counts); or by more approximate measures of handfuls, mugfuls, and supermarket portions.
There are sheets in the file for organic and standard values of produce. It is up to you which one you use, since you know your own gardening practices best!
The calculator uses quite broad categories of crops, and the purchase values are based on averages from different varieties. So apples are divided into 'cooking' and 'eating' apples, but not into different varieties within that (e.g. braeburn and discovery would both just be counted as 'eating').
You can either keep track of your yield overall and put in the total amount of each crop picked (e.g. "500g of redcurrants in total"), or add any sequential harvests (e.g. as =200+300).
The spreadsheet will do the calculation, and update the small report at the top with:
How much it would have cost you to buy that produce in a supermarket *
= The ‘total crop’ value.
How much of that value is directly a result of insect pollination **
= The ‘bee value’ value.
What percentage of your crop value is directly the result of insect pollination.
= The '% directly from bees'. ***
* based on online prices from Waitrose, Riverford, Abel & Cole, and Sainsburys 2022.
** Pollination requirements of fruit and vegetables are taken primarily from Carreck and Williams (1998), Corbet et al., (1991) and Klein et al., (2007).
*** 'bee' value is really 'insect pollinator value' since insects that are not bees do contribute, but for ease / space, we use 'bee value'!
How it works / where the numbers come from.
Assigning a cash value to home grown produce can be difficult. People garden for different reasons, including: pure enjoyment; access to unusual varieties of crops; reduction in food carbon miles; education; and so on. Saving money is a possible motivator, although not necessarily the primary one. Plus, gardening actions have costs themselves, in time, equipment, compost, seeds etc.
Rather than try to take every possibility into account – and produce something that is overly complex for the project task – the Garden Shop Calculator takes some shortcuts to represent all the other factors that might be in play for users.
That shortcut is Waitrose prices.
Waitrose is in the high-end of supermarkets in the UK, often identified as having higher prices than other supermarkets. However, they have stated a strong focus on using environmentally friendly farming in their supplies and promoting leaf marque standards for their fruit and vegetables, as well as scoring highly on a 2022 Which? report into sustainability.
So, the calculator is based on Waitrose prices. These are on the higher end of what you might find for similar types of fruit / veg for in other supermarkets, but we are using this higher price to encompass the range of other values that growers may be getting from their food, without having to work those out directly. Of course, Waitrose does not sell everything in the calculator, so we have used other sources too. The main other one being Riverford – a UK organic veg box delivery scheme – to make sure we have organic prices to use as well.
Sources of all pricing information is available on request (it is actually in the calculator itself if you unhide some cells). Correct as of 23/06/2022. Broadly, the prices came from:
1) Waitrose ‘Essential’ range
2) Waitrose own brands (if Essentials not available)
3) Other supermarket source (e.g. Sainsburys; Ocado)
4) Closest equivalent food / or the organic value if there is no other info available. (e.g. most things that are unusual raspberry relatives use raspberry values)
1) Waitrose Organic / Dutchy range
2) Riverford Organic values
3) - Other veg box delivery / supermarket organic range
4) Closest equivalent food if there is no other info source available