Roots 'n' Shoots: Composting: Kitchen waste, NPK & Fertilisers

Why is RnS Moving to

Google had brought out an algorithm update in May 2017. With previous updates like Panda or Penguin, Mr G had penalized blogs or websites with low quality content and those more focused on aggressive adverts (including multiple ads or pop-up ads in articles). However, many blogs/websites that weren't shady got penalized beyond recovery too and a lot of people lost their income. The May 2017 update has had wide-scale effect on blogs and websites, but without any explanation from Mr G as to why or what it does. RnS has been hit by it too and hard. RnS organic search stats (i.e. users from Google) have dropped by 75% since. Even though RnS is not a source of income, I tried to figure out why RnS is being culled. It seems that it doesn't really have anything to do with RnS per se, but likely because RnS is FREE and not paying for page ranking (via AdWords or Ad Ranking). Now it is likely being aggressively shoved to lower page rankings to accommodate the paid ads.

I cannot rely on Mr G anymore to get RnS' content where it is needed. So I am busy moving RnS to Wordpress where you can find me as Whisker Flowers @

I am also imposing 301 redirects from already moved posts and pages!

- The Shroom - (AKA Whisker Flowers)

Composting: Kitchen waste, NPK & Fertilisers

Home Style Composting

Composting is a very important section of any good gardening book – but they all fail to mention how wonderful good ol’ kitchen waste is. Some say it takes too long to break down and that it must be degraded before planting... but that is a bunch of half-truths. Kitchen waste will break down while your plants grow and the plant roots will assist with decomposition. So when you plant new seeds or seedlings - add a little kitchen waste to the planting hole, as you would fertiliser. It also is easier to add kitchen waste directly to the garden, since many gardeners do not have enough space for a compost heap or bin. Composting kitchen waste is very sustainable, since it is readily available, high in nutrients, reduces the waste on landfills and is a way of accessing a free service provided by mother nature to assist with your vegetable gardening efforts.

The lowdown: Kitchen waste has an astounding amount of nutrients and breaks down within 1-2 months depending on the season and what you put in the ground. Most things (tea bags, leaf based stuff, whole fruits and vegetables, banana peels) breaks down in 1-2 months, stuff like avocado peels take longer J.

B&B - Banana and Beet Lore
Banana peels and beet leaves are some of the the best nutrients from the kitchen (next to comfrey, but that’s not kitchen waste J) you can give the soil and the plants – I always aim for high potassium foods – not just for fruit and flowers, but for plant resistance! Earthworms love them too!

I did a nutrient study to determine, which is the best kitchen waste to add to my home-style composting, focusing on most of the main plant nutrients – NPK, Mg, Ca, Na:

Food (100g)
Amount of nutrient (mg)
Comfrey (herb)
N, P, K
1190, 100, 740
Mg, P, K
27, 22, 358
Beet Greens
Ca, Mg, P, K, Na, Fe
117, 70, 41, 762, 226, 2.6
Carrot Greens
Ca, P, K, Na
33, 35, 320, 69
Borage (herb)
Ca, Mg, P, K, Na
93, 52, 53, 470, 80
Turnip greens
Ca, Mg, P, K, Na
190, 31, 42, 296, 40
Orange Peel
Ca, Mg, P, K
161, 22, 21, 212
Ca, Mg, P, K, Na, Fe, Zn
37, 33, 129, 332, 25, 1, 1
Ca, Mg, P, K, Na, Fe,  Zn
25, 33, 108, 244, 5, 1.5, 1.2
Ca, Mg, P, K, Na
15, 17, 38, 262, 2
Basil (herb)
Ca, Mg, P, K, Fe
177, 64, 56, 295, 3.2

Now I only added the elements in the nutrient table that matter (values of one type of food relative to the trend amongst all the food), do not want to bore you with numbers. So regarding the table, comfrey is best, followed by borage, but these are herbs and need to be grown specifically for composting. So for kitchen waste: Beets, Bananas, Carrot, Basil … I think you get the picture J. So no throwing away carrot or beet greens! The earthworms will get you!!

Earthworms & Wormeries

Kitchen waste:
Just about anything that is plant based, leaves, roots, shoots, flowers, fruits … seeds! Anything rotten or that you won’t eat (carrot greens) go back into the ground – if it is safe to lick, it goes in!

Just have a large plastic container with a lid in your kitchen that can take about three days worth of kitchen plant material – more than three days sitting it goes really gloopy. Once full, dig a hole in the garden and plop it in there - you can plant immediately once covered. Or put in a ‘drier’. I dry any excess kitchen waste for, which there is no space in the garden – a very large plastic drum (laundry holding size) and put it in the sun – mine takes 1-2 days to dry out to a crisp! Breaks down in a snap when it is dry and then added to the soil.

Kitchen waste you can give to garden in copious amounts:

Banana peels
Carrot leaves
Beet greens
Herb leaves (everything, lavender, basil, sage…)
Herb stems
Vegetable shavings (after peeling)
Tea bags!
Spent coffee
Onion leaves
Roots (from spinach or lettuce harvesting)
Citrus peels
Rotten stuff: tomatoes, peppers, apples…
Spent spices
Flowers (rose petals, squash flowers)
Turnip and radish greens
Peels (pineapple, squash, carrots, potato)

Basically anything that is plant-based can go into the ground – do not bother with processed foods like bread, cheese – as these have little nutrient value for plants in terms of NPK. If you do throw whole fruits (with seeds) into the ground, expect to have some germinate – simply pluck them out and throw them back onto the soil, if you do not want to keep the plants they produce.

I always add some compost and fertiliser to the soil in addition to the kitchen waste (every month during summer, every two during winter).

Compost should be well degraded as to not burn the plants, so use ‘diluted’ add about half the volume of compost to the soil you want.

For granulated fertiliser – sprinkle on, DO NOT FOLLOW THE SUPPLIERS INSTRUCTIONS – USE LESS – a lot less – sprinkle a little bit only to dot about the ground, every two months. That should be enough, as fertilisers are synthetic and potent – so a little goes a long way. Rather use powdered fertiliser that is added to water, follow the supplier’s instructions for these as they are less potent and more "bioavailable" – can be used once a month to every two weeks without plant burn.

The fertilisers I use are:

2:3:2 NPK Granulated fertiliser (Cultura)
2.5:1:5 NPK Soluble powdered fertiliser (Starke Ayres Nutrifeed)

The Starke Ayres stuff is wonderful – the plants respond really well to this and can be used often (every two weeks for the tomatoes – cause they are hungry!).

I also add wood ash to my garden regularly as it contains a lot of potassium and other wonderful bioavailable nutrients for the garden... also used as cutworm control J

Update - 2017 - 

Please have a look at my series Sustainable, Productive & Economical Vegetable Gardening comprising of several articles in which I have expanded on my conservation agriculture principles in the garden:

            Part 1: Vegetables Worth Growing
            Part 2: Conservation Agriculture
            Part 3: Integrated Organic Gardening
            Part 4: Vegetable Garden Planting Guide & Management

Organic Composting Methods: Related Posts


Green Manures

Instant Compost
Comfrey: Organic fetiliser

Soil Profiles

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  1. Hi Shroom,

    Thank you for your informative blog. I have recently laid out an organic perma-culture, suburban food garden, also in Roodepoort (in Wilgeheuwel, on the West facing slope looking down onto Strubens Valley). The vegetable garden is set on reasonable slope towards the valley. It has been terraced to take the slope into account and to prevent run-off. It enjoys reasonable shelter. As I have recently moved to the area I am not familiar with the frost patterns and endemic sowing seasons. History of the area says that the valley was used extensively for food crops at the turn of the last century. As you live in the area, could I ask you which Winter food & herb crops you would grow from seed - direct & indirect? Would you propagate indoors, in a greenhouse or directly into well composted beds?

    Many thanks,


  2. Hey hey!
    Welcome to my crazy little universe - I am happy to hear the locals are finding me :)
    Frost is usually late July to August (sometimes we have had late frost in September). Considering the amount of dew this year, we have a sneaky feeling that black frost might be possible this year! Hopefully not... but some fruit trees (especially from the apricot/nectarine family) have a habit of blooming during the frost times so just take some precautionary measures with frost fleece to protect the buds. Most of the other plants should be fine and I usually sow summer crops middle to late August depending on the activity of the other plants. If you want to be safe you can plant around the Spring equinox (20-23 September), which should be clear of frost and promise some rain!

    Winter vegetables have been doing poorly the last two years as the winters have been to warm (around 20oC) - last year we had no winter crops, beautiful plants but no production... this year I have some beans going as they grow at a wider temperature range and they are doing quite well (the how to grow Beans post it still on the home page of the blog). Most of the other vegetables, such as peas, all the cabbages and leafy veg like temperatures below 20 degrees to grow and produce properly. The biggest problem is that you plant your winter veg and hope the temperature drops LOL! I think next winter should be colder and then I would be able to get some broccoli and peas for the first time in three years!

    These days I rip out the summer crops by mid February, let the soil rest till mid March and then I plant our all the winter crops. It seems that they like to 'grow' when it is hot and then crop in the cool winter - so these would be lettuce, pak choy, cauliflower, brussels, broccoli (I recommend planting the stem types), dill, fennel, baby spinach, Swiss chard, beans, radishes and all types of onions. I have a few how to grow posts on each of them that you can find under the Index Page. I am still sorting out a few kinks with the winter garden after which I will post on how to set it up, but that will probably be when I have a decent winter harvest again! Our winters are short so it is best to just plant our everything (no staggering), since some of the plants such as the peas and large cabbages (cauliflower, brussels) need a long growing period.

    I try to direct seed as much as possible as I have noticed that the plant grow better when their roots aren't. However you might have a cutworm problem (cutworms come with lawns) who will mow down the seedlings - so you can put half a toilet roll into the ground, about 5 cm deep and plant the seed inside - that should keep the cutworms out. Once the seedlings have stems thicker than a pencil then the cutworms won't eat them anymore. I use Maria Thun's Biodynamic calander for specific fruit types for the summer garden - you can check it out @

  3. Had to break up my comment blogger was complaining - LOL!

    Summer crops are all of the Solonaceae Family (eggplants, tomatoes, peppers), Curcubits (Cucumber, squash and pumpkins), Maize, runner beans, carrots, beetroot, sweet potatoes, potatoes and just about every herb imaginable. I highly recommend planting a basil not only for culinary purposes, but for the bees, other pollinators and insects as well - they love basil! I have a whole bunch of how to grow profiles under the Index page for these. I plant these in two batches (one during September according the Biodynamics calander and another in December). This gives you enough crop for the whole season, just experiment with the second batch of zucchinis and pumpkins as you might encounter the Curcubit fruit fly during January which destroys the entire crop! See more here @

    If you can start the summer garden early by using a greenhouse - it would benefit you greatly, but sometimes the late September frost can catch you out or even worse the hail - one year I had nice knee high plants and three days after moving them to the garden the hail massacred them! The last few years the hail has been just awful - due to the whole El Nino system... and it is completely unpredictable, the only warning you have is when you see huge black clouds coming from the mountain (South-Western direction) and the hail falls at that angle too! I have my annual Weather Report in July, so next month I will elaborate more on recent weather events, but the previous ones also have general seasonality information in them @

    I only propagate herbs and I usually do this in December.

    I hope this helps with the start up! Keep me posted on all your gardening happenings!
    Good luck! :)

  4. Hi Shroom,

    Thank you for your comprehensive advice, there are some real pearls! As the garden is new and compost was bought in by the bakkie load, I have planted a whole lot of commercial (as opposed to organic) seeds to habituate the soil before planting all the organic seeds in August/September for the Summer crop. I missed the Winter sowing as the garden was only ready for sowing less than a month ago. It will be an interesting experiment as to what seeds can withstand being sown, either directly or in trays, in the middle of Winter and still germinate and grow. Luckily I have no real attachment to the outcome of the commercial seed, bar the Inca corn which is organic and the seeds a gift from a friend. Sowing the commercial seed was really just to prepare the soil for sowing the organic seeds in late Winter/Spring. So far 8 out of 10 of the Inca corn has germinated (I kept half back just in case) and is growing well. Hopefully it sets seed before the hailstorms! I have a small greenhouse, just large enough for 4 or 5 dozen seedling trays so will start of seeds late August, bar those that like going in direct. I have also planted berries (blueberry, cranberry, tayberry, blackberry and gojiberry) and hope they are well enough sheltered by the boundary wall where they will be trellised. Some sort of protection for the hail is something I should start thinking about now, thanks for the advice! Fruit trees are fig, olive, lemon & lime and a weeping mulberry. I have buyers remorse on the mulberry as I have a suspicion, beyond the nursery's insistence to the contrary, that it is cultivated more as an ornamental than for great berries. It is grafted so there is a little bit of hope! Fruit trees still to go in are pomegranate, mango & paw-paw. The primary objective being an urban food garden. I have a wormery and a plastic composter so am hoping that beyond the initial outlay, it will be fully sustainable from here on out. As soon as there is more to see I will send photos.

    Have a super day and thanks again for the excellent advice!


  5. Hi everyone. I have a vege garden in Westdene. 4 raised beds each 2m x 1m. When do you plant runner beans broccoli and cauliflower?

  6. I planted runner beans as a summer crop and I would also recommend only planting one of them as they make a lot of beans! Broccoli and cauliflower are both winter vegetables (planted after autumn equinox). The last to winters have not been cold enough for these to head properly - you can always plant a trail (2-3) of each next season and see how they perform (I would however recommend the stem broccoli or brocollini as they produce earlier and its easier for the plant to make more loose heads than one large firm head).

    Hope that helps! Keep me posted on your garden progress :)

    Good luck!


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