The Great Container Mix Experiment - Part 3 Coconut Husk Chip Mix

In the mail today, I had my coconut husk chips arrive from an online store. The husk chips come in a compressed block which expands as you pull it apart and add water.

The brand that I have found available in Australia is designed for use in orchid growing and has been pre-washed a number of times according to the product description. It is important to have washed coconut husks, as they may otherwise contain high level of salts.

Coconut Husk Chips

I have no set formula for this following mix, and in the past have made it up using whatever ingredients I had laying around and whatever needed to be used up at the time. I really like the texture and feel of the coconut husk chips, as the mixes always come out light and fluffy, and you can just imagine the pockets of air that sit throughout. Coconut husk chips also hold water extremely well.

In general though my mix contains mostly coconut husk chips, but also pine bark, perlite and compost. I always add a little composted bagged manure as well.

I have a number of plants potted in this mix, some of which have gone dormant throughout winter, and some that have put on slight growth. Weed seeds constantly germinate however, and from pulling these out, it becomes easy to see how the roots of plants seek out the husk chips, and their roots grow into the husks itself, a property that pine bark can't match.

Plant Roots Grow Right Through the Coconut Husks!

My logic might not be quite correct here, but I think that if plant roots can not only take up the vacant space within a container, but also through the media itself, surely this will allow more overall root growth?! At the end of this experiment I will upend all the plants and compare the root development of each.

Today I also received with my order a bag of diatomaceous earth, graded to a 5-8mm size. This product looks similar to perlite, or a white rock, and is in a similar size. It has quite a number of properties that make it suitable for container culture, such as its ability to exchange nutrients, buffer soils, hold water within its porous body and will not break down over time, so it suits itself towards long lasting potting mixes. Both coconut husk chips and pine bark also are long lived, and a media made from these substances can often last a number of years.

I decided to add equal amount of perlite and diatomaceous earth to this mix, something I have not tried before.

Making the Mix

As mentioned above, coconut husk chips come in a compressed block. It is quite light, and I prefer to break it up with my hands before soaking it. I used a whole block with this mix, which makes up about 60-70L pure coconut husk chips.

Compressed Coconut Husk Chips

With the Help of a Screwdriver it Took Only a Few Minutes to Break This Up

The coconut husk chips expand quite a bit more once wet, so I split it into two container to mix up in two batches.

Once Wet the Coconut Husk Chips Almost Filled the Wheelbarrow

Once I split the mix I added two pots worth of large composted pine bark pieces. These pine chips were rated at 15mm, and are double the size of most of the pieces used in the 5-1-1 mix.

Two 8L Pots Full of Chunky Composted Pine Bark 

After the pine bark I added one pots worth of perlite, and one pots worth of diatomaceous earth.

One 8L Pot Full of Perlite

One 8L Pot Full of Diatomaceous Earth

Diatomaceous Earth Looks Similar to Perlite, it is Made Up of The Fossilised Remains of Diatoms

Next I mixed everything up and then added one full pot of bagged compost, and half a pot full of bagged composted chicken manure. I also added one handful of dolomitic lime, a small handful of Osmocote and two handfuls of organic Dynamic Lifter, for comparison with the other mixes.

One 8L Pot Full of Compost

One Half 8L Pot of Composted Chicken Manure

This is the final ingredient for this mix, so I gave it a really good mix with the shovel, and added a bit more water to any dry bit of husk I saw. 

The Final Mix Looks Like This

Close-Up of the Final Mix- Very Porous and Light

I added the mix to my pots and lined them up ready for the experiment to begin!

In these pots, the closest three will all be grape tomatoes, the next closest fatalii chillis, the third closest basil or silverbeet (or whatever catches my fancy!), and finally banana chillis.

Previously I said I was going to germinate each seed in its respective pots, but due to the fact winter is not over yet, I have thought better and will germinate all seeds on a heat-mat in my greenhouse until they are of a size to transplant. This will mean that the pots will stay vacant for several weeks. In the meantime I will keep them damp, so that they don't become hydrophobic.

All My Pots Lined Up Ready to Begin!

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The Great Container Mix Experiment - Part 2, Making 5-1-1

In the largest forum on the internet regarding container gardening a very active forum member Tapla is an extremely useful source of information, who has grown container plants and bonsai for a number of years.

His latest thread on the topic, which is constantly being superseded is available here. He is often around and is very generous with his advice and time.

From the thread listed above Tapla lists the ingredients for his 5-1-1 mix as;

"The 5:1:1 mix:

5 parts pine bark fines, dust - 3/8 (size is important)
1 part sphagnum peat (not reed or sedge peat please)
1-2 parts perlite (coarse, if you can get it)
garden lime (or gypsum in some cases) 

controlled release fertilizer (if preferred)"

Note 3/8 inch is 9.5mm. So the mix calls for dust size pine bark to 9.5mm.

I have had mixed results with this mix in the past, but am slightly suspicious that it may in fact have been something I have done wrong. I am conducting this experiment in order to work out just how much of a benefit such a mix will give compared to plain potting mix or other media such as coconut husk chips.

As the 5-1-1 mix relies on the right size pine bark to work properly, in this experiement I am mixing two batches of 5-1-1 with two different types of pine bark to give it a proper chance to perform. The mix I made previously seemed too wet and sloshy.

The Ingredients

Pine Bark

I am using two types of pine bark, both graded to the size Tapla suggests, however one tending toward the larger particles and one tending to ward the finer particles. As my problems previously were made with the smaller pine bark fines, I have made mostly larger grade mix, with a single comparison with the finer pine bark for comparison.

Fine Pine Bark

Larger Pine Bark Pieces (most under 10mm)

Here is an indication on their differences in size.

Coarse VS Fine VS Perlite

Perlite

Perlite is a type of volcanic glass that occurs when certain minerals are heated to a certain temperature. It is very light and white and resembles the beans from a bean bag. Perlite is my top contender to why my previous 5-1-1 mix was so wet, as the perlite purchased from Bunnings is very fine. For this experiment I have tracked down a big 100L bag of coarse perlite, which can be found online or your local hydroponic store for around $50. 

Coarse Grade Perlite

Sphagnum Peat Moss

Sphagnum moss is the dead and decayed sphagnum plants that grow in peat bogs around the world. Care should be taken to find a source of peat that is sourced from renewable bogs. I found mine at a local nursery, and it wasn't particularly cheap at around  $80 for the bag below.

Sphagnum Peat Moss 

Mixing the 5-1-1

Mixing up 5-1-1 is very easy, simply 5 parts pine bark, 1 part peat and 1 part perlite. I start by using a wheelbarrow and a 8L pot.

First I measure out five pots worth of pine bark fines and add them to the wheelbarrow.

'Fine' Pine Bark Fines

'Coarse' Pine Bark Fines

Next add one pot worth of perlite

'Fine' Pine Bark

'Coarse' Pine Bark

Next I give it a mix through and then add one pot full of peat.

'Fine' Pine Bark

'Coarse' Pine Bark

Finally, the recipe calls for the additional of dolomitic lime. I added one handful, and one handful of slow release Osmocote fertiliser. I also added two handfuls of organic Dynamic Lifter.

Adding Dolomitic Lime and Osmocote

It is important to wet this mixture well after mixing, as peat moss and pine bark are quite hydrophobic when dry. When I wet this mixtures they both turned to a similar mud-like consistency.

'Fine' 5-1-1

'Coarse' 5-1-1

I then potted up the mix into its pots ready for the experiment. Below is my rows of course and fine 5-1-1 ready to go, as well as the pots of plain potting mix (with added dolomitic lime, osmocote and Dynamic Lifter for consistency). 

Three pots of 'Coarse' and one pot of 'fine' 5-1-1. Potting mix in the centre. 

Next post will be making the coconut husk mix, which kind of has a bit of everything in it. Just waiting on the main ingredient to be delivered!

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Introducing the Great Container Mix Experiment!

Im back! With the beginning of August we begin our countdown to Spring, although you wouldn't be the first to wonder whether or not Spring had already arrived! Across our suburbs cherries and other fruits are blossoming, and a few of my potted plants are showing the first signs of life!

I will leave our unseasonable warmth for another post, for all winter I have been thinking upon more and more  upon another pressing issue... Soil mixes.

Much of last year, I spent my time searching for the best soil medium that would grow a wide range of plants, and I could use as a reliable medium that would both retain a good amount of moisture, but also would also be porous enough to allow the plants roots access to plenty of air.

As can be read in my previous post on soils, the role of the soil medium is simply to anchor the plant, provide dissolved nutrients and water, and to provide air.

I began my search on the GardenWeb forums, and pretty soon into the adventure found that a forum member ‘Tapla’ was renowned for having two soil mixes that met all these properties. One of these mixes his ‘5-1-1’ mix was made up of three ingredients; partially composted pine bark fines, perlite and peat moss.  

After finding suitable pine bark fines, I quickly potted up a number of plants including fig trees, blueberries, bay tree, dwarf lemon tree and a dwarf peach. 

All potted in Tapla's 5-1-1

I was very excited and expected a tonne of new growth. The season however by this stage was nearly over, having potted everything up in the beginning of February, the final month of summer.

Besides one or two blueberry bushes, I saw very little growth from any of my plants after planting in the mix, despite having a month of summer remaining. I have various possible theories why, in particular some very hot days which might have stressed the plants. I have a suspicion that my figs in particular were heat stressed, because when the heat finally dissipated the figs started to put on some new leaf growth.

May 2013 - Where's my growth!?

Feb 2013

I had a couple of other issues with the mix, on most days I would water it in the morning, and come home to find plants wilting- despite the soil being obviously damp. A quick drink and plants perked up again. The biggest issue however came when I had some issues with my blueberries suffering a nutrient deficiency and beginning to show signs of leaf chloriosis.

Chloriotic Blueberry Leaves due pH

Blueberries are picky plants in their pH requirements, and despite the 5-1-1 mix being inherently acidic the water I was using was too alkaline, and was slowly killing my plants. I fixed this by adding small amounts of sulphuric acid to the watering can before watering, but in the process also added more soil mix to the plants.

It was during this process that I noticed that the soil mix was absolutely saturated despite not having been watered at all that day. The mix had collapsed to the point of a store bought mix, but seemed to be holding excess water, not the porous aerating soil I hoped for. I amended the mix, adding larger pine bark pieces, and the plants seem to be doing ok, although they are all now dormant.

Unhappy, I decided to follow in the path another forum user had suggested, coconut husk chips (CHCs). CHCs are the fibrous part of the coconut that have been cut into fairly uniform square sizes. The chips come in a compressed block that supposedly expands to make up to about 60L when hydrated. Coconut husk chips have some beneficial properties to pine bark, such as hydrating from a dry state easily, where pine bark fines tend to become hydrophobic once dry.  CHCs also held a good amount of air and water.

Using CHCs I have potted up most of my plants, and now only a few plants remain in the original 5-1-1 mix I made in February, despite having not had a chance to see if it is effective or not.

My current mix- Primarily coconut husk chips, with perlite and pine bark

 Still, doubts remain. Did I throw the 5-1-1 aside too quickly, and judge it too harshly? If I had potted in Spring would there have been a difference? Will the CHCs even perform well (everything has been potted whilst dormant).

The CHCs certainly look good when mixing, and look like they will perform an excellent job, but even this, perhaps, is unnecessary.

And so, beginning in the Spring of 2013 I intend to test all of this with an experiment.

The Great Container Mix Experiment

Introducing now the great soil mix experiment, where I will attempt to determine for myself once and for all the best mix to put my potted vegies and fruit trees into! Is it really worth all that effort to source fancy ingredients when a $5 bag of potting mix from Bunnings will do the same thing?!

There is only one hopefully, mostly scientific way to determine this. Grow a number of the same plants in different soil mixes and see how they perform under the same conditions. And to be super sure, I will grow a couple of different types of plants side by side.

I am going to grow four types of plants each in three different soil mixes and measure the differences in growth across the season. I am going to record all growth against a control group of plants using straight potting mix from Bunnings. In total, I will have three different mixes to test;

·         Pure potting mix

·         Tapla’s 5-1-1 mix (two versions)

·         My current experimental mix which is made up primarily of CHCs but also has pine bark, perlite, compost           and manure    

  

For this experiment I have decided to use four different types of plant so that my results are more than just the result of a particular type of plant preferring a particular mix. The plants I will choose for this are;

·         Grape tomato, which does not require staking

·         Fatalli Chilli

·        Basil (or possibly egglant)

·        Banana Chilli 

These plants have been chosen for their size and suitability for pots, and also based upon what I use a lot in cooking.

Plants will be grown in two different sized pots. Half will be in smaller 8L pots and the other half in larger 30(ish)L pots. All seeds will be germinated directly in the mix so that transplant shock is not a concern. 3 seeds will be planted in each pot and the most healthy seedling kept.

Plant growth will be measured in a number of ways, including germination time, height and apparent vigour. Fruit count and quality will also be recorded at intervals. Photos will, of course, be provided at weekly intervals.

I am quite excited to get this on the road, and have already mixed up the 5-1-1 mix! Read more in my other post!

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