Urban Food Forest Garden Yields, Three Years In

garden yield graph 2010

Here are the annual figures for the garden yields for the period of Oct 2010 – Oct 2011, the garden’s third year.

The annual production for this garden was 131kg in the first year, 202kg in the second year and 194kg in the third year (as a consequence of a minor disaster!).

The total garden bed area is 686 sq. feet (64 sq. metres).

The average monthly amount of produce was just over 14kg.

Here are some statistics which break this down further:

garden yield graph 2010
Garden yield figures for 2010

This graph is colour-coded for season – yellow (summer), orange (autumn), brown (winter) and green (spring).

The most significant anomaly is the “flat-spot” in August, this is what happens when you get seriously ill, are confined to bed, and can’t harvest anything for a month. Things like this really do happen in a real-life garden!

If we look at the monthly production figures:

Yields Per Month (grams)

200820092010
Jan22,2036,38514,769
Feb10,86013,8919,478
Mar11,01816,70020,813
Apr3,74849,05615,413
May15,56628,2775,304
Jun11,25140,13639,995
Jul14,3413,08544,176
Aug4,12821,804
Sep11,1558464,426
Oct11,25219,35120,393
Nov6,1491,1709,542
Dec9,5561,27410,067
Total 133,235 203,984194,376
Monthly Average10,93616,831   14,018

This year was fraught with disasters, mostly weather related, so we’ve fared pretty well considering…

Previously, Cyclone Yasi struck Australia – this category 5 tropical cyclone hit North Queensland on February 3, 2011 and caused major disruptions to the weather further south here in Melbourne. As a result, our weather changed from a hot, dry Mediterranean summer to a hot, wet, tropical one.

To quote a previous article report:

We experienced an unseasonably wet spring and an early summer, which has then made a reversal into cold weather, and then reverted back to summer heat. If that wasn’t bad enough, for the first time we’ve experienced what you’d call tropical weather, a period of very hot weather with continuous rain.

The result was pretty much a disaster for people growing food. It was reported in the news that the weather “…took its toll on cherries, table grapes, strawberries, stone-fruit and wine grapes, which have suffered cracking, splitting, marking, softening, fruit drop and disease outbreaks.”

In Victoria, commercial growers lost up to one-third of their early season stone-fruit and wine grape growers expect to lose one-fifth of their yields because they experienced the worst downy mildew outbreak in 20 years. they only managed to rescue their harvests by extensively spraying with fungicides!

It’s fairly easy to calculate the harvest losses for this year.

Stone fruit – I counted 52 full sized nectarines and 38 full sized peaches rotting on the ground under the trees. If I very conservatively estimate the weight of these fruit at 100 grams, we are talking about (52+38)x100=9000g, that’s 9kg of stone fruit.

Grapes – there were over 9kg produced last year, and the grape vine has been steadily increasing its harvest. If we once again conservatively assume that it would have produced at least as much as it did the year before, then that’s 9kg of grapes.

Tomatoes – since there was virtually no summer this year, expectedly, tomato yields reduced from 15kg last year to 8.5kg this year, so that’s a loss of over 6kg of tomatoes.

There were other losses, such as other vegetables, cherries, about three weeks worth of raspberries, but I wont bother counting this for now.

If I add up our figures for lost harvest, 9kg of stone fruit, 9kg of grapes and 6 kg of tomatoes adds up to a severely underestimated harvest loss of 24kg. If I add this figure to the harvest total, 24+194=218kg, which would have been 14kg more than last years harvest figure at the very least, but hey, this is the real world, and disasters do happen.

Essentially. this represents a 4.7% loss in harvest, but from a more positive perspective, it shows that the garden design is rather resilient and we were able to harvest 95.3% of our usual amount of produce even with a major disastrous weather change. I’ll count myself lucky that I have a biodiverse food forest, unlike the commercial monocultures, where commercial growers lost up to one-third of their early season stone-fruit. That’s the benefit of polyculture vs. monoculture folks!

If we break down the figures by type of produce (fruits, vegetables and berries), we can see the how much produce we got in each of these categories.

FruitYield (g)
apple 8,264
apricots 220
babaco 8,666
cherry guava 151
feijoa 218
fig 8,643
grapefruit 5,120
lemon 10,029
lemon guava 207
lime 165
mandarin 42,954
mulberry 2,123
orange 3,203
pepino 6,839
plum 12,651
pomegranate 6,680
rockmelon 773
sloe berry 341
total 117,247
2009 total 127,723
2008 total 53,636

This year, fruit production decreased by almost 8%. This decrease is expected, as all the grapes, cherries and stone fruit were lost due to unseasonal weather. The biggest contributing factor though was a major pruning of the pomegranate tree, last year it produced 47kg, this year it only produced less than 7kg, but then again, more than 2/3 of the tree was pruned away! I have planted a few new fruit trees, so there are still many young trees that still have not established themselves yet. My pear trees are now three years old now and might produce their first fruit this year. It appears that fruit trees take around five years to establish and give reasonable yields, and it is evident that yields increase progressively from year to year as the trees mature.

BerriesYield (g)
blackberry26
blackcurrant15
goji berry64
raspberry5,687
redcurrant236
strawberry1,088
total7,116
2009 total4,021
2008 total2,584

The performance of the berries is once again outstanding this year, as it was in the last year. Last year yields have increased by 56%, this year they increased by a whopping 77%. This berries I added last year – youngberries, thornless blackberries, loganberries, thornless gooseberries, black currants, red currants and golden currants are growing well. I’ve added a few more this year, some boysenberries, silvanberries, lawtonberries and marionberries! I’m expecting next years berry harvests to be phenomenal!

VegetablesYield (g)
broad beans20,267
cauliflower553
chilli473
climbing beans47
edible canna760
eggplant764
jerusalem artichoke9,400
kale220
lettuce536
loofah846
potato2,501
pumpkin1,917
rhubarb1,199
silverbeet1,700
sweet corn1,954
tomato10,056
water chestnut1,115
yacon15,705
total70,013
2009 total70,231
2008 total75,052

This year I actually got exactly the same amount of vegetables as the year before, that’s 70kg, even though I couldn’t harvest anything for a whole month being bedridden with a bad fever, I forgot to harvest nearly all of my potatoes (they re-sprouted after being left too long in the soil!) and most of the annual vegetables ‘bolted’ and went to seed after we had a two or three extremely hot days during a very mild spring.

So, I’m really producing 70kg of vegetables a year without really trying…

To get some perspective on these yield statistics, we see that production is commonly measured in terms of yield/acre.

  • One acre is approximately 4047 sq. meters

Now, if we look at my garden, still in its infancy at three years of age, its best production to date is:

  • 202kg/64 square metres

To convert this to acres, we do dome simple maths: 4047/64 = 63.23 (so you can squeeze approximately 63 of my whole gardens into one acre!)
Now, a bit more math to get the yield per acre: 202×63.23 = 12,773kg/acre

Without the harvest losses, the theoretical yield per acre: 218×63.23 = 13,784kg/acre, almost 14 metric tonnes per acre.

So, my 3 year old garden that is just getting started is producing the equivalent of 12,773kg/acre, in other words, close to 12.77 metric tonnes per acre!

Now that I’ve added a few more trees – a mango, another babaco, a persimmon, and another half dozen varieties of berries, I’m curious to see how the garden will perform over the next two years, even in adverse weather conditions.

Also. in case people miss this fact, this garden is completely organic, no pesticide was used this year at all. I’ve used a bare touch of organic neem horticultural soap or white oil in previous years, but absolutely none was required this year. Fertilizer was provided courtesy of my three worm farms and five compost bins, and a few bags of sheep manure to replace the nutrients lost from the produce I give away!

The fruit trees are starting to fruit once more as summer arrives once again, the berries are beginning to grow quite vigorously, and by all appearances it’s promising to be better than ever this coming year!

6 Comments

  1. shanegenziuk says:

    A fabulous piece of data gathering, and shows how efficient Jerusalem artichoke and Yacon are in food production.
    I had so much JA last season I passed it on to a local fruit and veg shop, and should have about 30kg of it come Autumn.

    Was at your place this Winter, and if you are ever out around Bentleigh way let me know so I can return the favour.

    1. Blackthorn says:

      Thanks Shane,

      Yes, root crops are the most productive land plants, they provide excellent returns from a small space!

  2. Frogdancer says:

    I was there with Shane and want to thank you for the rhubarb and raspberry plants. Currently harvesting my first boysenberries and am amazed at the amount of fruit I’m getting.Just magic!

    1. Blackthorn says:

      You’re welcome, glad the raspberries have gone to a good home!

  3. sanjita says:

    So wonderful and plentiful information you have put together for a newbie garden enthusiast like me. Thanks a bunch ! I am in a sub-tropical temperate climate of san francisco bay area planning to put some gooseberries and currant. But I was told my climate may not be cold enough for them, same way not hot enough for tropical fruits. How do you pull off growing babaco and currants in the same garden?

    1. Angelo (admin) says:

      Currants need a specific number of hours of cold, a ‘chill period’ for them to produce. We have fairly cold winters (without frost) and very hot summers (but unfortunately quite short). Each climate has its challenges! You can try growing sub-tropicals, and ‘low chill’ varieties of plants and trees that require a winter chilling period. There are some low chill currant varieties out there that may be worth a try.

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