Do you screen out fines from pine bark mulch for 5-1-1?

7 years ago

last modified: 7 years ago

When making the 5-1-1 mix, I put the pine bark mulch thorough a 1/2 inch screen to get rid of large pieces but do not screen out smaller pieces. I have noticed that trees in this mix do not need watering for long periods - like 5 - 6 sunny days - while those in gritty mix require daily watering. I am thinking that perhaps I should screen out mulch particles smaller than 1/8 inch.

Do you think that 5 - 6 day watering intervals are excessively long?

Do you screen out smaller that 1/8 inch particles?

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axier - Z10, Basque Country (Spain)

7 years ago

last modified: 7 years ago

I will tell you my experience with 5-1-1 mix, which I changed for a 6-1 mix (I will explain it).

Until one year now, I used a commercial mix of compost and peat for citrus containers, with very good results in the short term (several months), but with further problems due to organic matter decomposition with lake of air and and the resulting problems.

Then, I decided to move to 5-1-1 mix, but it is difficult to find pine bark of 3/8" size. Repti bark and Orchid mixes are very expensive.

I buy 1 inch size bark mulch in 6 gallon bags at a very good price. Later, using a pruning woods chopper, I triturate the bark mulches and screen out pieces bigger than 3/8" size.

What I get is a family of bark particles from fines to 3/8" size.

I tested by myself several mixes in a container of 25 Oz volume and 6 inch high and I got the following results:

5-1-1 mix (chopped and 3/8" screened bark+perlite+peat):

Total pore volume: 300 ml
Aeration pore volume: 130 ml
Total porosity: 40 %
Aeration porosity: 17.3 %
Water-holding porosity: 22.7 %

6-1 mix (chopped and 3/8" screened bark+perlite):

Total pore volume: 400 ml
Aeration pore volume: 250 ml
Total porosity: 53.3 %
Aeration porosity: 33.3 %
Water-holding porosity: 20 %

As you can see, I got better results, by far, from 6-1 mix, without peat.

I decided to try without peat, following a Josh (Greenman28) advice in an old post. He said that sometimes he didn't use peat in 5-1-1 mix with good results.

Peat decomposes faster than bark, and you know that decomposed particles penalises aeration.

Well, after one year of use of 6-1 mix, I bare rooted the past week a healthy Tango mandarin grafted on Poncirus trifoliata in a 12 gal container, for planting in ground, and I can tell you that the mix was in a very similar condition to the original, and I don't remember so well developed and healthy roots in a container citrus plant.

I am very satisfied with this mix.

Just one additional care with it, you have to monitor more closely the fertilization, because minerals leach out easier than in a traditional peat mix. In any case, it remains for an acceptable time.

And, coming back to your question, I don't remove fines.

If you removed fines, in my opinion, it would be imperative to use peat.

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Comments (7)

poncirusguy6b452xx
7 years ago
Has anyone used pin bark mulch and run it through a shredder bagger to reduce the size of th large pieces instead of screening them out.
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The top one looks great. The bottom one is probably acceptable, I've used bark with a similar amount of sapwood. Not ideal but probably OK. For 5-1-1, the intention is that you should not need to screen at all. Guidance for 5-1-1 pine bark is dust to 1/2" with a majority being close to 3/8". Your top bark looks like screening at 1/2" is probably a waste of time for the tiny amount it might eliminate. Before bothering to screen bark destined for 5-1-1 for fines, I'd mix up 1 pots worth (with appropriate amounts of perlite+peat) and see how it drains - you dont need to use a plant for this. Since you already screened some, you can do a side by side. I have found myself screening 5-1-1 bark for fines, at times, but usually that means you just need to shop a bit more for bark sources. You can also eliminate the peat if the bark starts out with "too many" fines. Daniel
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myermike_1micha
7 years ago
Right on Axier!!!

Vladimir, in some cases I have to screen out most of the fines and add no peat at all...That's in the de composted pine bark.

Of course with the rest-bark you have to add peat or turface
suzuchan
7 years ago
I've wondered about that, too, due to Al's posts about container soils compacting. Our garden shops here sell screens for screening fines (insect screen size)

, or so it seems to me. I'm constantly poking in my pots with a rod to be sure the soil is loose and aerated (as well as to check moisture) but I've wondered about going for a coarser mix next repot.
ubro
7 years ago
Steve, I use larger pine bark nuggets and run them thru my leaf blower/mulcher and it chops them up pretty good, but wear ear muffs, it is extremely noisy. I got the idea off another link in GW, and they suggested you make sure it has a metal impeller, not plastic. And remember to zip up the bag, I forgot once and I had a rooster tail of pine bark shooting randomly all over with the larger pieces pinging off the side of my greenhouse. :)

I like the idea of being able to just use the pine bark without screening and eliminating the peat.
nomen_nudum
7 years ago
last modified: 7 years ago
Dreamy sifter on the far right too but that's a different species

Side note: A hello to you too as requested.
myermike_1micha
7 years ago
In most cases. there really is no need to screen out the fines all depending on what you use...Every ones interpretation of the bark fines can be so different..

Vladimir, if you are talking about the bark we use, you really don't have too)

Do you screen out fines from pine bark mulch for 5-1-1?

axier - Z10, Basque Country (Spain)

Comments (7)

poncirusguy6b452xx

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