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Soil mix experiment

Posted by naikii 9a / 8b (My Page) on
Thu, Dec 12, 13 at 4:42

Hey all, after reading this forum for ages, and learning all I can, I decided to run a little experiment this year comparing various plants growing in different soil mixes.

I especially got interested after a debate in one of my first posts regarding coconut husk chips vs pine bark fines.

I have 3 okra plants one growing in 5-1-1, one in plain potting mix and one in a mix made mostly of coconut husk chips. I then have 3 Fatalii Chillis again growing in 5-1-1, plain potting mix and coconut husk chips. Finally 3 banana chillis once again in 5-11, plain potting mix and coconut husk chips.

After a long delay of 7 weeks after transplanting I finally got down to measuring and looking at the differences, and have found some interesting and mixed results.

The experiment will run until our first frosts knocks everything dead in April or so, so these results may change over time, especially since it looks like we are in for a really hot summer!

The chart below shows the percentage change in growth of each plant in each mix, measured 1 week after transplanting into their mixes, and today, 7 weeks after initial transplant.

Its worth noting that a particularly cold morning which got down to 2o C totally stopped one okra dead in its tracks, and although it still lives, it has done nothing since then, hence 0% growth.


Follow-Up Postings:

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RE: Soil mix experiment

Interesting experiment.
What is your fertilization regimen like? Did you add any nutrients to the initial mix? Are you watering them all equally, as well?

Josh


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RE: Soil mix experiment

When making up the initial mixes all had an equal amount of slow release fertiliser added, and an equal amount of an organic pellet fertiliser (Dynamic Lifter) and dolomitic lime. The Coconut huk chip mix also had some composted chicken manure added. I didn’t add the chicken manure to 5-1-1 or straight potting mix, mainly because in some posts Tapla talks specifically about not adding manure or organic composts etc, whereas a slow release fertiliser is ok, and I wanted to compare to the mix I was using for my figs, which has some chicken manure added.

They are all fertilised each Saturday with a full dose of soluble miracle grow, from the same can, and all watered on the same schedule, every second or third day dependant on how hot it is. They are placed in an area so that they all get the same amount of sun.

The Fataliis and Okra are in 40-50L containers and the banana chillis are in ~10L containers.

All plants were similar in size on initial transplanting, except for one banana chilli, which was smaller than the other two, and went into the coconut husk mix. All were grown from seed.


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RE: Soil mix experiment

Ah, so it's not really a controlled experiment, as far as the chicken manure is concerned. Still interesting to see what results you have at the end of the season.

Josh


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It is a point that I thought upon, until I considered that my objective was to compare the standard recipe for 5-1-1 with the recipe I was using for my figs. I couldn’t add manure to 5-1-1 and have it remain ‘5-1-1’, and similarly couldn’t remove the manure and still be testing the same mix I was using for my figs.

So I consider it as valid as comparing say the effectiveness of something like two different brands of fertiliser, or two different brands of off-the-shelf potting mix, one brand might have additional ingredients/additives to the other, however that’s kinda the point, which blend of ingredients gives a better result when used under the same conditions.

And in any case, the plain potting mix which I bought for $2.50 a bag has the same slow release fertiliser and lime added as the 5-1-1 but no chicken manure and so can act as the control group for comparison.

Edit; so whilst at the end of everything I may not be able to answer the question was it the CHCs or the manure that made that particular group fare better/worse than 5-1-1 or plain potting mix, I should still be able to state that a mix with CHCs plus manure performs better or worse than plain potting mix which performs better or worse than standard recipe 5-1-1

This post was edited by naikii on Thu, Dec 12, 13 at 22:13


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RE: Soil mix experiment

Coconut husk is used in many products and grades. What exactly did you use? Small grade, medium grade? I heard as a mulch it's not that good with some mold problems.
But looks like a decent amendment for potting soils.

This post was edited by Drew51 on Fri, Dec 13, 13 at 11:15


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RE: Soil mix experiment

I have tried using a mixture of 8 parts red lava rock (about 1/4" size) and 2 parts bagged potting soil for my house plants. But I only use it on corn plants, it worked better than using pure potting soil.


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The coconut husk chips are 5-8mm, I use them for many plants and have not had a problem with mold before.

If you would like to see the method etc making the mix I posted how I did it, as well as making the 5-1-1

Here is a link that might be useful: Making coconut husk chip mix


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Thanks yes I'm considering it for my own mixes. Depends what I'm trying to grow. I believe a mix should be based on what plant you are trying to grow. I don't have any faith in a one size fits all theory of potting mixes. Each plant group has different needs.


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Nathan did you get the Mt Sylvia brand of diatomite?

Alan


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yes, 5-8mm grade

This post was edited by naikii on Sat, Dec 14, 13 at 5:43


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RE: Soil mix experiment

To me pumice looks promising as an amendment. I don't like the idea of handling diatomaceous earth.
I like pine bark for blueberries over husk chips because they are more acidic. But for other plants it seems better.


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I use Pine bark, perlite and azalea mix for my blues which works well


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Naikii,

I feel peat is best, but lot's of peat probably in azalea mix.
I used equal parts of peat, pine bark, and perlite with sulfur and cottonseed as fertilizer. I also hit them with ammonium sulfate three or four times a year too. Future mixes will have pumice instead of perlite. I use only rainwater to water. I'm adding two plants next spring. A couple excellent Southern Highbush types. Southmoon, and Sweetcrisp.
I decided on them from growers in the orchard forum.
Northern types grow better here, and what I have, these southern ones will be grown in pots and kept in the garage in winter. My Northern highbush are in 4x4 raised beds surrounded by strawberries. Eventually the strawberries will be removed once blueberries reach full maturity (5-6 foot ).
They are about 3.5 ft now. I love the berries, so much better than store bought, unreal! Same with the strawberries! And peaches, and raspberries, and plums...


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I had my first Southmoon berries this spring, Drew, and they were outstanding -- early to ripen, crisp, big, and very sweet. I think you'll be very happy with the addition. After all of the accolades from growers on the fruit forum, I'm looking forward to trying Sweetcrisp next spring. I have a small plant that should be fit to yield a few berries.


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Cool Shazaam! I look forward to getting the plants. Blueberries are awesome, I want more too, but no room. When I move I will have a lot more room. I will add many cultivars. Now is a time for me to experiment with soils, getting back on topic. thanks all for the suggestions, and what you use. I have really expanded my thoughts about soils from this forum. Once you know the basics, it gives experimenting a better chance of success.
I have an old bird bath in which I grow small cacti outside.
This is really ornamental and I want to make a mix that is cool looking, and functional. The mix never has to be moved, only the plants. I was thinking of this mix

Decomposed granite
Silica sand (very large grain)
red lava rock
pumice
akadama

It should look awesome and function much like the gritty mix. I may add pine bark too, then it is a variation on the gritty. akadama is a clay-like mineral that replaces turface.
pumice and lava rock could be looked at as substitutes for turface too.


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Well 3 weeks later, little has changed.

I am beginning to have doubts that the time/effort/cost of preparing specialised container mixes is worth it!

Plants in plain $2.50 bagged potting mix continue to perform as well as, or better than 5-1-1, and coconut husk chips.

Compare these fatalii peppers, the plant in the middle is growing in plain potting mix, the one on the right coconut husk chips and the one on the left 5-1-1.

Although since week 1, the plant in coconut husk chips has put on the most growth percentage-wise measured by total height, the plant in the plain potting mix is greener, larger and more dense than the others, with the coconut husk chips and 5-1-1 only slightly behind.

Here are the total percent changes in growth from week 1 to week 10.

This post was edited by naikii on Thu, Jan 2, 14 at 21:45


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RE: Soil mix experiment

Thanks, I think your experiment reveals a lot. I'm going to make some soils next spring, but beyond that I think i will just use Fafard soils as a base and alter to my needs.
I grow a lot of fruit, and vegetables that demand a lot of attention, so the less I have to do the better. Especially if the effort is not going to result in better yields. In another thread a mixture of peat and compost seemed to grow tomatoes beyond expectations. Ideally those mixes should have performed better, but reality begs to differ. Good job! Keep us updated!


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i use shredded coir in amending my outside tropical plant beds.. i like it better than peat..not the price..but..here in utah..it helps around my banana and EE plants the soil doesnt dry out as fast ..
i had thought of using coir chips in my potting mix..but the thing with coir..it retains water.. and for my purposes..using pine chips/fines is better.. i too am a big fan of pumice ..
2014 will only be my 2nd yr using it..but my big amorphophallus plants (inside) have a version of al's
5;1:1 potting mix.. i use 70% pine fines/chips. 30% pumice.. and i had great success with it growing season
2013..


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It really is quite amazing to me, 3 months ago I would have put money for sure on the potting mix performing far worse than either of the other two.

Perhaps, as the season goes on, there will be a change, and the cheap potting mix will begin to falter...


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@ lomodor, the coconut husk chips do seem to remain moist more so than the other mixes.

With the banana chillies in particular, being in smaller pots, the largest, growing in plain potting mix will wilt if not watered every day, the 5-1-1 will wilt if not watered before a very hot day, but the coconut husk chips have not wilted once (although it is a smaller plant).

Before I started the experiment I did some research into the advantages of each soil and came across a site who claimed that coconut husk chips did hold more water, but also simultaneously held more air.

This is what made me really want to test these benefits for myself.

Specifically, the site ( http://www.ladyslipper.com/coco3.htm ) said;

"Two medium components did defy logic and have the capacity to hold large amounts of air and water simultaneously... ...While holding approximately the same level of air immediately after watering and as it dried out over a 5-day period in 2.5-inch rose pots; it also held substantially more water. After six months under greenhouse conditions, fine fir bark had broken down and dramatically lost its air holding capacity and stayed quite soggy, while the small coconut husk performed essentially as it did when new."


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RE: Soil mix experiment

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Fri, Jan 3, 14 at 11:47

so how many pounds each of N,P, and K per cubic yard are in each mix? I ask because your experiment seems to be testing fertilizer levels more than anything else.


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They all had an equal amount of slow release fertilizer, a pelleted organic fertilizer and dolomitic lime added.

The coconut husk chips had some additional chicken manure.

They get equal amounts of soluble fertilizer weekly.

There are no differences in fertilizer at all between pain potting mix and 5-1-1.


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  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Fri, Jan 3, 14 at 15:52

plain potting soil even the cheap stuff often has nutrients added to it.


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So then, you are suggesting that the nutrients added to cheap bags of potting mix are so effective, that it eliminates any differences that would be gained by having a soil mix with improved air/water retention properties?

Fertilization trumps soil medium properties/composition in improving growth in containers?


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  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Fri, Jan 3, 14 at 16:18

The biggest problem however is the small sample size of one for each treatment. Using different plants to expand the sample size doesn't work as is evidenced by the huge disparity in growth rates between different plants that get the same treatment. The difference between plants in all treatments is greater than the disparity between treatments. So you are actually running 3 experiments simultaneously with sample sizes of one. Without a larger sample size it is impossible to determine whether the results seen are because of the treatment or random chance. The other problem with such a small sample size is that you can't control for location. That is why nurseries use randomly assigned blocks when studying treatments. Specifically, the problem is that perhaps one container gets an extra 20minutes of sunlight per day and that either causes an increase or decrease in growth. Without controlling for that with random blocks, you can't determine if the results are a result of the treatment or the location.

I don't mean to be a PITA, I just see people attributing meaning to meaningless results from poorly constructed experiments far too often. Thankfuly in this case, there won't be real world implications like there might be with say a poorly constructed rat feed experiment.


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Naikii,

I think your experiment points out the obvious. The 5-1-1 mix has too much bark to be useful. a 3-1-1 mix is better.
Most potting soil like Fafard, and many others whom livelihood depends on what they make all pretty much use a 3-1-1 mix. Even a 1-1-1 mix is decent. Many universities recommend this. I use a 1-1-1 for blueberries myself. I find it works better. But I probably will start using pumice instead of perlite as I want to recycle the product to raised beds and perlite breaks down to useless mush over time. Pumice keeps working for about 20 thousand years. The peat and bark are just a compost mulch that will break down to nutrients, they add little to soil fertility, but don't harm it either. The pumice will keep the soil moist and aerated for my lifetime and beyond. Lava rock is also as good as pumice too, a little heavier, but is basically just like pumice. Sometimes you can get that cheaper.

No professional soil makers use a 5-1-1- mix, that tells you a lot. They have already done the tests. Bark is cheaper than peat moss, so if it worked they certianly would use more bark and save money and offer a better price point. It doesn't work.

This post was edited by Drew51 on Fri, Jan 3, 14 at 16:34


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Edit: new posts appeared before I responded. My apologies. I see that Nil added an excellent comment. I'll leave my original comment, however, for posterity.

I think what Nil is suggesting, and pardon me for speaking for him/her, is that in this experiment the cheap potting medium is not the Limiting Factor.

Josh

This post was edited by greenman28 on Fri, Jan 3, 14 at 16:34


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Drew, at least a few professional nurseries use a mix that is very close to the 5-1-1, sometimes with even more bark. Conifer nurseries especially....but also I heard Debbie Flowers talking about bark mixes three weekends ago, and how her horticultural students use this type of mix for sale plants.

Josh


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Well tbh this was never meant to be a conclusive experiment done to research standards to conclude anything.

Pretty much, having used bagged mixes for years I wanted to improve growth and yield and came across these forums. I read about how to improve mixes through Al's posts and was excited to give them a try.

I also read about different potential medium such as the chc and thought the only real way to decide would be to test them out and see how they go.

My expactations were something like; potting mix would grow plants just as well as previous years, but due to the reasons spoken about in Al's threads there would be a marked difference when using 5-1-1 or other mixes designed to have no perched water and improved aeration.

Now, all my plants are healthy and producing well, regardless of mix. Had I just potted everything into 5-1-1 or chcs I would have probably been extremely happy with the results of the change and attributed everything to the mix used. There is no real way to compare plant performance across years because of the multitude of changing variables.

So that's when I thought I'll just grow the plants side by side. I'll use a couple of different plant varieties and they will be grown under the same conditions. These conditions will be the same backyard conditions that the plants would have been seen this season regardless of mix.

The hope of course is that there would be a distinct difference between groups that reflects the extra work and expense that goes into sourcing ingredients and putting them together.

I am not growing in a theoretical or nursery environment where optimum growth can be obtained under perfect conditions, but rathera real life, this is my backyard this is where I grow my plants and the methods used to grow them.

The fact that for my backyard over 10 weeks there is no difference so far to me says that the return on investment is questionable.

I have no attachment or desire for any particular mix to succeed over another, I have figs and nectarines and apples and grapes in coconut husk and grapes and peaches and bay and blueberries and tomatoes in 5-1-1 or slight variations or mixtures of the two. All do well.

I just want to say at the end of the season, growing seasonal vegetables is it worthwhile or not to make up specialized mixes such as 5-1-1 or am I going to see the same results using cheap bagged mixes.


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RE: Soil mix experiment

"I use a 1-1-1 for blueberries myself. I find it works better."

Fall Creek Farm & Nursery disagrees, Drew. In fact, they suggest an 8-1-1 blueberry potting mix that includes 8.5% more bark than does Al's 5-1-1 mix. Similarly, Four Winds Growers recommends a blueberry potting mix that's composed of up to 80% bark (they suggest a range of ratios from 6-3-1 up to 8-1-1). Perhaps you should let them know that "it doesn't work," because apparently they haven't figured that out for themselves.

This post was edited by shazaam on Sat, Jan 4, 14 at 12:20


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"The most common components in an outdoor container nursery mix are bark, sphagnum peat moss, and sand...Softwood bark typically comprises from 80 to 100% of a mix...Many growers use a recipe of 80% pine bark, 10% peat and 10% sand."

This conspiracy of ignorance seems to be wide ranging, Drew. It looks like Fall Creek and Four Winds aren't alone in utilizing a mix "that doesn't work," and this ignorance isn't just restricted to blueberry cultivation.

Here is a link that might be useful: From the UMass Extension: CONTAINER NURSERIES��

This post was edited by shazaam on Fri, Jan 3, 14 at 22:15


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Thanks naikii for posting your experiment.

Coconut husk chips do seem ideal for roots. I spend a lot of time digging up roots in my garden & containers to see what they do. They certainly like finely porous medium, (especially partially rotted wood). My plants never did well in 5-1-1, partly b/c the bark I used, while small, wasn't porous at all.

the husk chips look similar to hydroponic rockwool.


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Your experiment has proven to be interesting thus far, naikii. While I'm happy with the results that I achieve with bark based mixes, it's always good to look for opportunities to challenge your assumptions. I'll be curious to see how your experiment plays out through the remainder of your growing season. In the meantime, I have some questions for you. First, what do you know about the contents of the bagged mix that you're using? Does it list the ingredients? Also, I'd like to know more about your fertilization methods. What slow release fertilizer did you use? What's the analysis? How much did you apply per liter of potting mix?


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This coming spring I intend to use a 5-1-1 or similar mix for growing trees, mostly conifers, in small plastic containers. Depending on the type of tree I will use more bark or more drainage material.

I've noticed that the local independent or family-owned garden centers typically use lots of bark for their soil mixes, while HD and other big box stores who do not grow their own plants more often than not use lots of peat and sand. Several times I've purchased trees and shrubs from Lowes and found the roots buried in thick, heavy muck, totally soaked with water. There's no way that most plants, except those that crave constant water, could possible thrive in that kind of soil for any length of time.

Based on what I have read here the bark mixes are a big improvement. Maybe conifers and other trees are not so fussy but those peat and sandy soils typically found at the big box stores just seem very unhealthy and compacted.

Thanks.

TYG


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If one is an experienced and seasoned gardener , he/she can grow in various media. Lets don't forget that medium is just a medium to hold and provide the nutrients and moisture that plant needs You can solve DRAINAGE and moisture retention by many ways. This experiment, although might not be FULLY conclusive but it is indicative what I just mentioned above.

Having said all that, I have a feeling that bark based mixes are worth trying and that is what I am going to do this coming season. It might not be 511. Might be 4-2-1. I might also introduce another component to it , like compost and generic inexpensive potting soil..


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@Shazaam the bagged mix didnt have any ingredients sadly, simply stating something to the extent of 'balanced nutrients for all your plant needs' or something similar.

Initially, I added osmocote, ingredient profile below;

And organic dynamic lifter, on their website the ingredient profile are;
Composted chicken manure, Blood and Bone, fish meal and seaweed
NPK analysis: 3.7 - 2 - 1.8
WA NPK analysis: 5.4 : 1 : 2.7

As I was mixing, to each full wheelbarrow (40L pine bark) I added one full handful of osmocote and two full handfuls of dynamic lifter.

Weekly I use a full dose of soluble miracle grow.


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Although I still use 5-1-1 for many plants,I want to take a moment to talk about why I wasn’t entirely satisfied with the results from my 5-1-1, especially my figs, and decided to change many of my plants into coconut husk, and then later making me decide to grow some plants side by side to see if I made the right decision.

Last year in January I began a thread to ask about advice onto what soil mix I should use to pot a variety of plants, specifically figs, blueberries, a bay tree and a dwarf nectarine. You can read through here if you are interested; http://forums2.gardenweb.com/forums/load/contain/msg0120561912795.html?72

28 days later I came back with a follow-up on how the plants were going since they were re-potted into 5-1-1, and in most cases no plants were doing particularly well! This thread is here; http://forums2.gardenweb.com/forums/load/contain/msg0301115119857.html

Because of this, when many of my plants went dormant in winter I potted them into a new mix, in larger pots using the coconut husk chips.

After bud break all my plants took off in their new mix. Unfortunately I dont know if this would have happened anyway, had they remained in 5-1-1. Perhaps their growth now is because they have not been disturbed after bud break. Perhaps it was too hot last year. Perhaps there is another cause.

Either way, take for example two of my original figs- White Adriatic and Black Genoa. In the 4 months from Feb to May and up until the first frosts, many of my plants did nothing, or put off a single leaf or two.

Now, in just over 3 months since they woke from dormancy, in coconut husk chips all my figs (and my other plants in husk) are doing amazingly.

2nd Feb 2013 White Adriatic planted into 5-1-1

19 March 2013 - 6 Weeks Later

5 April White Adriatic - small amount of growth

23 September - Breaking bud in coconut husk chips

9 October - Less than a month later

22 November - About 6 weeks after breaking bud

Now

Black Genoa
Feb

April

October after being put into coconut husk while dormant

Today


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RE: Soil mix experiment

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Sun, Jan 5, 14 at 1:31

I understand that people want to do experiments in their backyards. I like doing them as well. I just think that people have to be aware that experiments that are constructed this way with too many variables don't provide you the information you think it does. When there are too many variables that are not controlled all you end up learning is that one time you had one plant grow at a recorded rate in a specific medium. The problem is you can't really have any idea why. Was it light, nutrients, available water in the medium, humid microclimate due to being in the middle, etc. All this doesn't mean that backyard gardeners can't do quality science. We can. But sometimes we have to let some of our desires go for a single season in order to get results that are meaningful. For instance if this study had only used a single pepper variety there would be 9 plants with 3 treatments and that would be the makings of a decent block 3x3. Now that would still not really be enough to fully control for location, you would want to repeat that block a few times getting 27 plants (good enough for the backyard). Now sure 27 pepper plants of all the same variety sounds like waaay too many of the same pepper, but for one year you just make a whole lot of pepper jelly or something and give it away for xmas. You just have to give up having a bunch of different varieties.


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RE: Soil mix experiment

Its been a number of weeks, but I thought I would update again, its week 19 now, and I got a bit distracted with the birth of our twins 3 weeks ago!

Anyhow, results look quite similar to my previous. Plain potting mix continues to perform admirably, doing better in some instances than either 5-1-1 or coconut husk chips.

The differences in most cases between 5-1-1 and coconut husk chips is minimal, sometimes one slightly outperforming the other, but nothing extreme.

My fataliis in particular are doing great, and I really love the look of the bright yellow pods.

Side by side it would be hard to say there was any difference in the fataliis.


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I consider your experiment conclusive for all practical intent and purposes. To me all 3 plants are about the same, with no noticeable visual difference among the.

Having said that, I have more faith in 511 than before. I am not looking for a miracle medium. As long as it does just as good as others, that is fine with me. What I like about 511 is that it is cost effective. I can make a mix at about $3 per cubic feet. Plus, you can never kill a plant by over watering, since it has good drainage.
Depending on the structure of the pine bark, one can play with the bark to peat ratio. For coarser bark, I would alter 511 to 4-2-1 or even 3-3-1


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