Each season this year I have posted on the Top 5 crops for that season based on their value space ratio. Value Space Ratio is a concept introduced to me by Mark at Mark’s Veg Plot and is a tool I use to try and ensure I am maximising the productive space within my somewhat limited gardening area. The basic idea is to work out the amount of value a crop produces taking into account the amount of space it occupies and how long it occupies that space. The hard part of this calculation is getting the value part right.
For me value is a combination of:
- The monetary value of the crop. I use the Woolworths Online price for conventionally produced produce. This is not because I want to devalue my crops but simply to give a realistic estimate of the base level of how much I save gardening. Also I’m lazy and I can check the prices easily online throughout the year.
- The benefit of having it fresh and readily available. This incorporates both the taste and vitamin benefit you get from eating the crop straight from the plant, as well as the convenience of having the plant on hand and ready to harvest when you need it. An example of a plant which scores really highly in these areas is parsley: you can harvest a bit or a lot depending on your needs. It tastes better fresh and the vitamin content is generally higher when freshly picked.
- The taste differential. While the obvious crop here would probably be tomatoes I also think potatoes score pretty well on this measure. This is entirely subjective of course but also hugely important to me.
- The availability of crop (ideally relatively sustainably/cheaply) elsewhere. Potatoes are not going to score highly on this measure as they store well and are readily available at the farmers markets. Fresh horseradish on the other hand would store well as its not that easy to find. Garlic also scores well here as if you don’t grow your own you are left with a choice of either paying a lot for it at Farmers Markets or buying often tasteless stuff with ridiculously high food miles attached (at various times of the year we import garlic from China, Spain & Mexico).
- The benefit to the garden of growing that crop – this might be aesthetic (I’m thinking chillies or climbing beans here) or as in the case of crops like broad beans, the nutrients they add to the soil.
I don’t think I’ve perfected how to weight each of these categories but using equal weightings across the board these are this years Top 5 crops:
- Cucumbers
- Parsley
- Coriander
- Basil
- Silver Beet
If you group the herbs together the list becomes:
- Herbs
- Cucumbers
- Silver Beet
- Salad Leaves
- Kale
Based purely on monetary value the list was:
- Cucumber
- Silver Beet
- Herbs (lemongrass & coriander scored particularly well)
- Shallots
- Passionfruit
My tomato crop wasn’t great in 2012 so this affected the scoring a fair bit and in previous years I think they would have made the top 5. Otherwise (the cucumbers excepted) the list is pretty heavily geared towards cut and come again style crops which I guess makes sense as they are generally productive for a larger proportion of the period they occupy space in the garden.
Is there actually a spreadsheet you’re using for this calculation? Or is it more back of the envelope?
Yeah I have a spreadsheet that I record all my harvest weights on and I use it to calculate VSR as well. My maths probably isn’t good enough for the back of an envelope….
Very impressive! I think I use my intuition at this point (“oh, the eggplants did much better this year than two years ago”) but getting some actual data is great. But weighing all season would be a drag!
Sometimes value is also based on your own desire to grow a crop. I’m lucky now that I have enough space to grow what I want. I can’t raise all my seeds, but I can grow my veggies. So I really don’t look at value anymore. Or I never, never would have grown mustard seed. I knew it would be a low value crops.
Very true! My experiments with turmeric and ginger definitely fall into this category, somethings you just have to do for fun don’t you. I have to say i use the system more to prioritise amounts of crops that eliminate things that i enjoy growing. Seeing the results the first things I will always make sure i have space for are cucumbers so in that respect I find it really useful.
That’s my girl! Another convert to VSR. I’m probably less scientific in my application of the principle than you are, but I do believe we have to go through a thought process like this in order to make sensible decisions on what to grow.
It has been really illuminating I must say. There are things in my garden that i don’t think i’ll bother with again and its nice to have a spreadsheet justify what would otherwise be a gut feeling.
Very interesting read. I only have a courtyard garden so space is always on my mind. My priorities are: salad leaves (any sort), herbs (most economical I find), spring onions (mainly because I only use a few at a time and don’t want to buy a huge bunch only for it to waste in my fridge), chillis and beetroot (because it’s hard to buy beetroot with the leaves still intact!) Great blog.
Thanks Auds – those crops are my priorities too. You might not save much money on the chillies but they are fun and I love the plants themselves. You point about beetroot is a good one – and even if you could buy them with leaves intact it would probably mean the actual root had wilted a bit as its water transfered to the hungry leaves.
I love it when other people ( you and Mark) do the hard work for us all. Thank you both of you. Considering about the only things I am likely to be picking are cucumbers and basil I am even more delighted with your calculations!
you couldn’t have chosen better if you tried could you? Hope you get rain soon!
I certainly go through a thought process like this even if I don’t do it as analytically as you. I agree with your first four values, the fifth is less important to me since I garden in raised beds and my soil improvement is perking away in the compost pile (although not so much here in January). At first I was surprised at all the herbs in your top 5, but I agree (although I would have rosemary in there somewhere). A Summer Dance cuke from my garden is better than anything I can buy for any price. Silver Beet is something I would never buy from a store here because the quality is so bad, and we only have it because I grow it.
The herbs feature so highly on my lists because I use a lot of them and they are comparatively expensive to buy plus the convenience value of having them on hand is invaluable I guess.
I like your criteria for calculating the value of a crop – I’d also have to factor in how well the crop would grow given the conditions we have here. I’d love to grow more of the crops that need long, warm summers, but that just wouldn’t work.
I like the Value Space Ratio to an extent. There are many ways in which I determine what I want to grow and when. Over time I have had to use a measure to decide whether to grow a crop again or not. The two main factors for me are: 1. Did it produce well and 2. Is it highly prized by myself, my family, or potential buyers. If the crop doesn’t fit either one of these categories it is out. We have problems producing tomatoes very well here. Instead I grow a lot of cucumber-melons. They do really well in our hot climate!
Interesting. I think everyone approaches it from the angle that works best for them. Not sure i could ever stop attempting tomatoes though – having said that they do (or should) do pretty well here.
Do you managed to weight all your harvest. I know its a bit tricky with the kids ;).
Yeah I do try – I don’t manage everything but enough to get a general idea. i have to admit to being better at it at the start of the year than the end though.
I don’t weigh my stuff (apart from for a week when I was really enthusiastic, about a year ago!) as I usually just dash out and grab veggies as I need them and don’t even think about it. One day, when things are more leisurely, I plan to and I reckon I will enjoy seeing the tallies.
For now, I just go by my gut and think – yep, those broad beans were prolific or nup, that garlic was crap. 🙂
Yes – I am a nerd it has to be saidf I do get a ridiculous amount of pleasure from seeing the harvest totals push my spreadsheet from the red (acccrued cost of creating the beds etc) to the black.