Winter ponderings about my Mel's mix

Hi all, 

I'm 4 years into my small-time SFG - two 4x4 beds in my front yard in Zone 5 suburban Indiana, my only unshaded real estate. I have experienced decreasing yields over the last several years due to a number of causes and am hoping to set myself up for greater success this spring.  (I need to troubleshoot on several fronts, but this question is meant to focus on my Mel's mix.)

Is there any way to assess the current ratios in my mix? I have been adding a diverse mix of compost each year as prescribed, but my mix just doesn't look like it did originally. It is still loose and easy to plant in, etc. - it just looks like there is much less vermiculite, and it does seem to retain water less well.  I am also considering that I may have had an "oops" in 2020 where one of my composts may have contained a good deal of peat and I wasn't paying enough attention to how the supply chain was causing manufacturers to make "adjustments" to their products. I am not opposed to starting over entirely to make sure I get the mix right, and I am inclined to think it might also help with disease control.  I wanted to see what others think here - does anyone have experience with diagnosing MM ratios, restoring MM, or with getting a fresh start by replacing MM? Thanks in advance!

Welcome to the boards!  You probably don't need to overthink trying to analyze the ratio of mixes in your current soil blend, but you can easily "refresh" the mix. Vermiculite does break down in to a powder over the years, and becomes less effective.  I periodically add a layer of coarse vermiculite to top of a bed, and then work it into the top 3 or 4 inches with a hand cultivator. That greatly improves water retention.  You may also be interested in adding some worm castings to your beds to improve the nutrient and microbe levels.

Note: What part of Indiana are you in? I spent my youth near Valparaiso, many years ago.

Hi riled, welcome to the forum!  I agree with OG, you probably just need to amend with some straight up good quality compost and top off the beds with more vermiculite.  I have to do that every few years.  Plus the MM seems to shrink, I think from compaction as well as actual loss from harvesting.  

I have used chicken poo from TSC, worm castings, and will add blood and bone meal too depending.  And I do have a kitchen scrap compost bin to help!

OhioGardener wrote:Welcome to the boards!  You probably don't need to overthink trying to analyze the ratio of mixes in your current soil blend, but you can easily "refresh" the mix. Vermiculite does break down in to a powder over the years, and becomes less effective.  I periodically add a layer of coarse vermiculite to top of a bed, and then work it into the top 3 or 4 inches with a hand cultivator. That greatly improves water retention.  You may also be interested in adding some worm castings to your beds to improve the nutrient and microbe levels.

Note: What part of Indiana are you in? I spent my youth near Valparaiso, many years ago.

Thanks! Will definitely add some coarse vermiculite this time - very helpful to have some confirmation that it does degrade and my eyes do not deceive me!  And yes, I am a huge fan of worm castings! Was thinking about scratching some into my house plant mixes too, once we get through the winter.... 

I'm in Tippecanoe County - I get up to Valpo/Hammond area occasionally...

riled wrote:I'm in Tippecanoe County - I get up to Valpo/Hammond area occasionally...

I am familiar with that area. There are relatives living near Battle Ground, and we occasionally get to visit there.  If you were closer to the Ohio border, you could get fresh worm castings from a local worm farm here - but, they don't ship. I've had great success with them.

Hi Riled, Welcome to the Forum!

So, your Mel's Mix is only 4 years old?

If you started with medium Vermiculite, it may be broken down further and not be as visible. If you started with coarse Vermiculite, and mixed in the compost additions each season/year, you should still see it. If you started with medium, you can add 1/2" - 1" of coarse at this 4 year mark.

The accidental addition of compost with peat moss is not fatal, but you need to add straight compost from now on. Do screen bagged composts and any home compost using a frame with 1/4" hardware cloth to remove wood pieces.

How deep are the beds and how high is the Mel's Mix? If you are short on head room in the beds, you can remove some of the MM, like an inch, to make room for the coarse vermiculite and composts. If you have been mixing in the new composts each time you amend, then it doesn't matter if you remove just the surface MM.

sanderson wrote:Hi Riled, Welcome to the Forum!

So, your Mel's Mix is only 4 years old?

If you started with medium Vermiculite, it may be broken down further and not be as visible.  If you started with coarse Vermiculite, and mixed in the compost additions each season/year, you should still see it.  If you started with medium, you can add 1/2" - 1" of coarse at this 4 year mark.  

The accidental addition of compost with peat moss is not fatal, but you need to add straight compost from now on. Do screen bagged composts and any home compost using a frame with 1/4" hardware cloth to remove wood pieces.

How deep are the beds and how high is the Mel's Mix?  If you are short on head room in the beds, you can remove some of the MM, like an inch, to make room for the coarse vermiculite and composts.  If you have been mixing in the new composts each time you amend, then it doesn't matter if you remove just the surface MM.

Thanks! Yes I think I did start with medium from my big box store, as I had trouble sourcing coarse... should be solvable now that I am connected here, as well as knowing my local area better too!   

I have 6" deep beds, and I filled it right up to the top - so 6" of Mel's Mix (replacing with compost each year till full & mixing in).  It seems to deplete maybe an inch or two over the course of the season. I'm snow covered right now, otherwise I'd check, but I imagine I'll have enough room or can make room as you say... and I think I've got some good kitchen scrap compost ready for the thaw!

Riled, Another option is to add another short board to make the bed taller to accommodate additional coarse vermiculite, compost plus straw mulch.

What material did you use to make the 6" bed? I ask because a 6" wide board is actually 5 1/2" which means the MM will only be 5 1/2" high. We often recommend using an 8" board with a finished height of 7 1/2". Plenty of room for MM plus mulch.