Tuesday, 3 February 2009

Save some money...make potting soil

Posted by: Paul Gardener
A posse ad esse (From possibility to reality)

Keeping costs down around the garden is one of the ways that we are able to really get our bang for the buck. It's how we put the "frugal" in our simple-green-frugal. Being in the northern hemisphere, I'm just a little while out from the time when I'll start planting a lot of the early season crops like cabbage, spinach, broccoli and the like as well as getting an early start on some of the slow growers like peppers and luffas. That in mind, it's about time for me to whip up this years batch of potting mix.

As I said before, I started gardening using Mel Bartholomews square foot gardening method. Some things I've tossed out and some I've kept in my regimen. One of the biggest holdovers I took from the process was Mel's mix. It's a simple and effective soiless potting mix that I've found to be really good for starting my seeds in.

If you've never made your own potting or starting soil, it's really a pretty basic thing. You're not really looking for a soil for the plants as much as you're looking for something that will allow good moisture retention, easy root growth and some nutritive value.

Of the three basic ingredients, two of them are things that I will only buy once a year and will use throughout the season. Those are peat moss and vermiculite. The reason I only buy these things once a year is because they are not cheap necessarily, and because they will go a long way.
Here you can see the three parts that I add to the soiless potting mix. The top item is the peat moss, it is mainly a conditioning agent that helps the mix to retain water. To the left is vermiculite whos main purpose in the mix is to also hold water. These two ingredients are both very resistent to compaction as well so they will give the mix a good texture and will be very welcoming to the new sprouts roots giving them a good headstart.

The third ingredient is the compost. This is the part of the mix that I make myself. It does well in both the water retention area as well as in allowing root formation, but more important it provides the new sprout with a consistent and slow releasing supply of nutrients.

When I make this mix, I generally get an old 30 gallon plastic tote that I have and add half bucketfuls of each one at a time in even ratios. As I'm adding the ingredients I will occasionally spritz the mix with some water from a spray bottle and mix it together. This helps the mix to combine better and starts to re-hydrate the dry ingredients. After I've added everything I can set it in the shed and bring it out as needed for all my potting or sprouting needs.

Doing this, provides me with plenty of mix for the cost of what a tenth of the quantity might cost if I were to buy it retail. It's just another way that putting a little effort into the things that we want and trying our best to do it ourselves can really add to our bottom line.

All the best to you all till next time!


Janelle said...

thanks, this is my first real garden and I'm starting from seeds so I am thankful for any tips :)


Rosa said...

~P, have you ever found a good substitute for peat moss?

We bought a big cube of peat moss when we planted our blueberries, four years ago. I used up the last of it last year. Since then, I've learned that harvesting peat moss is destructive to bog land, and causes the bogs to release a lot of carbon.

Last year I substituted in worm castings and a little composted manure after I ran out of peat moss, but that soil didnt' stay evenly moist so I lost some seedlings.

Hippy Goodwife said...

where oh where do you buy vermiculite? We are in pacific northwest and it is not available anywhere locally.

miss frugal in training said...

thx for the tip...I did read your post on your gardening method it seem simple enough i want to try it. I will be looking for the products as I am now preparing for my first vegetable garden... as my blog name states i am in training so every bit of help i can get is appreciated, especially when the cost is minimal. thx again.

Maureen said...

Ditto on Rosa's question, we are also looking for a peat moss substitute.

Chiot's Run said...

This is the same recipe I use.

Throwback at Trapper Creek said...

Hippy Goodwife, you can get vermiculite at Concentrates, Inc in Portland. They have all kinds of organic and conventional amendments.

Just be careful when using with vermiculite or perlite, wear a dust mask.

Kristin said...

The harvest of peat moss is not necessarily a problem. Elliot Coleman talks about it in one of his books and makes many excellent points. I blogged about it here:


That said, I am trying to do without purchased items at all. I'm using a mix of top soil (washed down the hill when our land was logged 50 years ago) and homemade compost. I figure they must have done this years ago as peat & other purchased items just weren't available to most people.

Darren (Green Change) said...

You can find vermiculite in nice large bags at hydroponic supply shops. It's very light (almost like popcorn!), so don't be put off by the size of the bag.

Instead of peat moss, I use coir. It's waste coconut fibre shredded up. When dry, it compresses down very compact, and it swells when you wet it. A half-brick sized block will expand to fill a bucket.

P~ said...

I was concerned about the peat as well. I still am honestly. It's one of the reasons that I try to limit my use of it to just once a year. Actually last year I even only needed to buy a small one. I have heard of Coconut coir as well, but try as I may I cannot find it anywhere but the hydroponic stores. They only sell packages of the bricks and they're very expensive.

Anonymous said...

This is the same mix I use as well. Good results last year. Used Coconut Coir too. You can use washed sand to sub for vermiculite, as per Lynn Gillespie who wrote "Cinder Block Gardens".

Anonymous said...

I'm brand new to this forum and I too an concerned, as others have stated, about the use of peat moss (actually should be called Moss Peat) and vermiculite. They are not the most environmentally friendly substances out there.

Paula said...

I am curious. We are planning to start our first garden this year ala SFG. I read the recipe for Mel's Mix and plan on using it. I am curious. Do you have to remake the mix every year? How do you use up the rest of the extra ingredients? When do you add compost to your garden? Do you ever add the peat moss or vermiculite? Thanks for ANY help on this!!!

P~ said...

No, you don't need to re-make it at all. You can add compost really at any time you'd like, but generally either when adding plants is a good time because it provides good nutrients for them. Also, in the fall I will add whatever finished compost I have left while I'm turning and prepping for the next year. As for the leftovers. Keep them handy for making more mels mix. It makes a great seed starting mix!
Best of luck to you!