In this, the second installment of this series, we will make the “dirt” or Mel’s Mix needed to fill the boxes we built last time.  Mel’s Mix, as stipulated by Mel Bartholomew, author of All New Square Foot Gardening is made up of equal parts peat moss, compost and coarse ground vermiculite.  The peat keeps the mix “loose” making it easy for plants to grow and develop roots, the compost enriches the mix; providing lots of nutrients for the plants, and the vermiculite holds water; making it available to the plant roots for a longer period than regular soil would.

The first order of business in this dirt making project is to visit the local garden supply store.  No, that’s not true; the FIRST order of business is to locate a garden supply store that carries the commodities we will need, and preferably in the quantities specified in the book.  And this is where the problems started for me.

Problems

First off, call the local garden centers and ask if they carry the compressed peat, course ground vermiculite, and multiple brands of compost.  Compressed peat (according to Mel) should expand to twice its volume when removed from its bag.  Course ground vermiculite does a better job of storing water than medium or fine, and because this stuff is expensive, buying it in the big (4 cubic foot) bags will save money.  Compost is made by breaking down vegetable matter with aerobic bacteria.  If you have a large compost pile of your own, you may use that instead of buying compost.  But you want to be sure your compost is “done” before you use it.

Compost

I started making compost from leaves, lawn clippings, kitchen waste (vegetable and rinsed egg shells only - no animal waste) and fireplace ash last spring.  I learned quite a bit along the way.  There are three major concerns to watch as you make compost; 1) keep the pile moist, but not wet.  A little water helps the bacteria grow, too much turns the pile into s sodden, stinking mess. 2) Aerate the pile by turning the pile with a pitch fork or by using a tumbler; the bacteria you want to cultivate needs oxygen to live.  If oxygen is not available, the aerobic bacteria dies and anaerobic bacteria begin breeding.  Anaerobic bacteria will produce compost too, but they take much longer and smell like a garbage dump while they do their work.  And 3) allow the compost to “cook” until the material is a rich, crumbly, black matter.  The inside of a compost pile will reach 150° Fahrenheit, which is hot enough to kill weed seeds if kept at that temperature long enough.  Also, mixing compost that is not done composting into your garden soil can kill your plants because the bacteria that are “rotting” your compost will attack the roots of plants growing in it as well.  Once the process is completed, this is not a problem. 

Commercial compost is usually made from a single source for each brand of compost.  Brand A may use the cast-offs of a mushroom farm to make compost, Brand B may use the hay and manure from a dairy farm barn, Brand C may compost saw-dust from a mill.  All are fine, none are complete.  Mel recommends mixing a blend of at least five brands of commercial compost to get the best nutrient mix.

If you make your own compost, get a wide variety of materials to go into it.  Yard clippings, fall leaves, kitchen scraps, and expended plants from your garden (except nightshades: eggplant, peppers, potato, tomato) are all excellent fodder for your compost mill.  You can add horse or cow manure (but not dog or cat poo) for added richness.  If you know a woodworker, sawdust can be added too, but avoid black walnut if at all possible, black walnut trees produce the chemical juglone in their root systems that kill certain families of plants, and this chemical will be present in the wood produced from a black walnut tree as well.  Common garden vegetables that will not grow within 50 feet of a walnut tree, or in soil containing juglone are cabbage and other cole crops, peppers, tomatoes, eggplants, asparagus, rhubarb and potatoes.  For details, Read This.

Quantities

How many quarts are in a cubic foot?  I didn’t know, and neither did our “expert” at the gardening shop.  Likewise, if a commodity comes in a 35 pound bag, converting it to cubic feet is a matter of guesswork.  A little standardization in the production of soil additives would be a very handy thing but, alas, that is not the case.

I went in armed only with a shopping list based on the formula Mel gave.  For my 6 boxes I would need 2, 3.9 cubic foot bales of compressed peat, 4, 4 cubic foot bags of vermiculite, and 16 cubic feet of compost divided between at least five different manufacturers.

The peat came in 3 cubic foot bales, not 3.9 and it turned out that this brand did NOT double it’s volume when released from its binding.  The vermiculite was available only in 8 quart bags.  Compost was available in 1 cubic foot bags, but they had only one brand available.  As a result I came up short on peat and vermiculite, and the compost is all from a single brand for the first year.  I’ll add my home-brew compost to fill the boxes starting next year.  Last year’s batch got tilled into the garden soil last fall.  Had I known then that I would be doing this, I’d have kept it, but I didn’t.

Weed Barrier

Attaching a weed barrier cloth to the bottom of your boxes is highly recommended, especially if you are fortunate enough to be able to simply plunk your boxes down on top of your lawn and fill them with the soil mix.  I’m using this gardening method primarily to deal with the problem of a sloping garden plot, so I had to dig the boxes in to level them up as much as possible.  And, the spot where the boxes are going was a garden last year, so there is no “lawn” to deal with.  But I decided to install the fabric just the same.  Since the boxes are already dug in, I stapled it to the inside of the boxes rather than trying to pull them back up and attach it to the bottom.  A 100 foot roll of 4’ wide weed barrier cloth only cost about $12.00.  What I don’t use in the garden will go under Marie’s flower gardens as she landscapes around the house.

Doling and Mixing

Once we gather our materials we set them into our boxes in the quantities needed.  Mel recommends using a large tarp to roll the Mel’s Mix around to combine it, but since I’m on this project by my lonesome, and because of our geographic features, I decided to mix up my Mel’s Mix right in the boxes.

Open the bags and pour out the contents.  Had the peat been what it was supposed to be, I would have used 1/2 a bale per box.  It wasn’t so I ended up using a full bale and ran short.

Our “expert” guestimated the 8 quart bags of vermiculite to be about 3/4 of a cubic foot.  They turned out to be no more than half a cubic foot, and somehow my in-my-head math turned out the result that to get 2½ cubic feet each for 6 boxes I would need 12 bags.  Wrong!  The calculator (which was lounging at home) says it should have been 21.  And the bags only contained a half a foot not three quarters, so I would have needed 30 bags at $6.00 a bag or $180 just for the vermiculite.  I think I’ll pinch-hit on this one and water a little more often.

The compost came in 1 cubic foot bags - even I can do that: 2½ bags per box, 6 boxes equals 15 bags.  Actually the formula requires 2.6 cubic feet of each item, so I’ll get an extra bag to divvy up, but to keep the math simple enough for my rotted brain to handle I was using 2.5 as my target number.  Compost is cheap: $1.40 a bag.

I used a flat-nosed spade to mix the mix.  I chose this tool because a regular garden spade, with its “pointy” end might snag the fabric and tear a hole.  I worked carefully and gently and it took a while but in the end the results were quite good.  Because of the shortage of peat the boxes are not quite full.  I’ll buy more and work it in during the coming week.

Next Up

The next step will be to make the grid and work out where I will plant what.  We will address that in the next episode.  Join us again next time, same plant time, same plant channel!

Last year when I put the garden to bed for the winter I pulled out all the nightshades for burning, then tilled everything else under and covered the dirt with a blanket of the fall leaves and grass clippings.  Over the winter we added kitchen scraps and ash from the fireplace.  There was nothing scientific about this, just toss it all in there somewhere.

Changes in the Offing

I was going to need to make major changes to my little garden plot this year; there is too much slope and heavy rains wash away my top soil and re-arrange my crops.  They don’t like being shuffled about and some of them decided they’d rather just die than live an integrated life style.

My first thought was to build several retaining walls of landscape timbers and terrace the garden to level out the growing areas.  Even at the beginning this did not seem like a perfect solution: Some of the retaining walls could get to be around 3 feet tall.  Those would require tie-backs to keep the dirt from pushing the walls over.  If I curved the walls, it would help but making curved walls from straight timbers is a bit problematic itself.  Digging (or drilling) pits for concrete anchors and burying steel tie-rods between anchors and walls is a fair bit of work, and the rods will interfere with tilling.  Then there is the issue of water retention.  Someone who knows this stuff warned me against this plan because water would just drain out the bottom by the terrace walls.

So I began looking for a better solution.  I came across several mentions of Mel Bartholomew’s Square Foot Gardening method, and it seemed like a good alternative.  This system has been around since 1981 and still has many devotees.  This method uses raised boxes filled with a special “dirt” mixture and a grid-work planting lay-out instead of planting in rows.  I decided to give it a whirl.

Building the Boxes

 A couple of weeks ago I borrowed a monster 8 hp rear-tine tiller and worked the garden again.  I won’t use that soil right away, but it will come in handy later.

Then we went to Lowe’s and bought the lumber and deck screws.  I’m going to start with six 4’x4’ boxes, so I bought twelve 8 foot 2x6’s; untreated, and a box of 2½” deck screws.  Total cost $96.00.  I knew I would need 72 screws, but the boxes only give a weight, not the count of screws contained.  They had one pound boxes and 5 pound boxes.  I decided to play it safe and buy the 5 pound box.  I could have used cheaper screws - this box set me back $30, but I was afraid cheaper, interior use screws would rust out and the boxes would fall apart.

I started by cutting all the 2x6’s in half and marking a line 1½” in from one end of each.  This helps me center the screws in the adjoining 2x6.

Then I drill three shank holes for the screws in just that end of each board.  I used a drill press because I have one handy - and because it insures that the holes are straight and square to the board, but a hand drill would work too.

I found a spot where I could stand one 4 foot board upright and lay another on a work counter and get the corners to come together properly.  I could have laid them on the floor, by my old knees complain bitterly when I do a lot of up-and-down, up-and-down stuff, so I prefer to work in a standing position.

I used a QuickClamp to hold the edges of the boards even, and the soft rubber faces helped keep the boards from shifting in and out while I drove the screws with a power screwdriver/drill.  I used a small framing square to get it close to square, but wasn’t going to get to obsessive about that.  This is not furniture after all.

I built each box in two steps, by first making two ‘L’ shaped sub-assemblies, then flipped one over and set it atop the other and drove in the screws.  This seemed to work better than trying to attach each side one at a time and having to roll the assembly around… especially at the point where it would be ‘U’ shaped and the chances of cracking one of those loose legs is pretty high.

While I have easy access, I take the chance to mark the top edges of the box for the grid work that will divide up the planting box.  I will probably just use string as a means of visually dividing up the box for planting, some use wooden slats.  This grid will yield 16 cells per box, each almost 1 foot square - it actually works out to 11 3/4” if you divide up the interior dimension equally.  I taped the yardstick in place for the photo as I am working alone, to do the marking I just held it in place against the left vertical and marked the rail at each point.

As I get them done, I carry the boxes out and set them on my loading dock and out of my way.  Three done, three to go.

As it turned out, when all six boxes were done, I had more than half of the box of screws left.  Two one pound boxes probably would have been sufficient for 6 boxes.  Oh, well, I’ll probably be building more, I’ll use these up eventually.

Then I spent about 3 hours scraping the composted, rich top soil back out of the area where I want to mount the boxes, and digging three of them in so they are level.

Good Dirt; Good Start

Our soil here is fractal red clay.  Red clay has two states of being: if it has rained recently it’s mucky and sticky; if not, it’s hard as concrete.  Neither state is ideal.  Being spring, it has rained - a lot - recently, so the clay under the garden soil was pretty sticky; gumming up my tools and my shoes, but at least I didn’t need a jackhammer!

The composted soil that I removed was nice, black, rich-looking soil and was just infested with earthworms.  It was very gratifying to see that my efforts to amend the red clay last year produced such good results.  I will use this composted soil in the Mel’s Mix that will go back into these boxes once I have them all in place.

This is all I can do for today, I’ll move more top soil and dig in the other three boxes during the evenings next week. 

In my next installment we’ll make up the Mel’s Mix and fill the boxes.  It should be safe to plant outdoors next week and I’ll transplant the seedlings that have already sprouted in an indoor mini-greenhouse.

Thanks for reading!