Questions about seed-starting and potting soil brands are some of the most popular that I receive. They’re tricky to answer because I’ve found that many of the best quality potting soils or soil-less mixes tend to be produced by smaller companies with short distance distribution. In terms of quality and ingredients, soil mixes vary widely — availability in your area will be very different than mine. Besides, I think there is something inherently problematic in wasting resources and money shipping potting soil long-distance. It makes more sense that this would be such a localized product.

My best answer is that it really pays to do your homework and spend your money wisely in this area. I am only comfortable recommending products that I have personally tested, or at the very least, have had the chance to touch and see.

What I can tell you is that I unequivocally do not use and do not recommend anything with the Miracle Gro name on the bag, regardless of whether or not it has OMRI (Organic Materials Review Institute) certification.

Here’s why:

Regardless of the quality of the product, The Scotts Miracle Gro Company is a Monsanto supporter and the exclusive distributor of RoundUp, a Monsanto product. I am committed to gardening organically, and as sustainably as possible and part of that goal is directed at keeping Monsanto and Big Chemical out of my garden in whatever form it takes. They may produce a so-called “organic” line, but as I see it, they want their feet in both worlds and wherever they can get our money. I garden on a budget, but I want the money that I do spend to support companies that are truly committed to the principals of organic gardening and sustainability. Any company that is in bed with Monsanto and continues to produce its own chemically-laden products is not truly invested in anything more than meeting their bottom line.

It used to be that I could talk about the practices and brands that I support while keeping silent about the brands that I don’t. But things have changed. These products are everywhere, and in many communities they are all that is available. Walk down the gardening aisle of any Home Depot, Target, or other department or big box/d.i.y store and they are all you see. New gardeners are often overwhelmed by their own fear of failure and pressured by marketing that leads them to believe that these products are necessary to grow a garden.

How to Find a Good Brand

– Ask around from sources that you trust: A good place to start may be a local community garden, garden shop, or farmers’ market that is committed to selling, using, and promoting ethically responsible organic brands.

– Look at the ingredients listed on the bag: A good potting mix will contain organic matter such as compost, seaweed, manure or mushroom compost, bat guano, bone meal, soybean meal, soft rock phosphate, greensand, fish meal, blood meal,and/or worm castings (to name a few) to provide nutrients. Some mixes contain slow-release, chemical fertilizer pellets that are not considered organic. Perlite, vermiculite, wood chips, rice hulls, turface, chicken (or other) grit, and/or sand is added to prevent compaction and increase drainage. Peat or coir (a renewable resource and peat substitute derived from coconut husks) are two common ingredients used to to absorb water.

– Lift the bag: I know this seems a bit shallow, but I find this is a good quick rule-of-thumb when you’re in a rush and you can’t see inside the bag or an ingredients list. I call this the 3 Bears Method. A bag of potting soil that feels really heavy for its size tends to be full of cheap fillers and compost. Depending on the source of the ingredients, it may be fine for the ground, but in a pot too many dense ingredients will compact and cut off air circulation in the soil. This inevitably leads to rot. Soil that feels too light for its size — not unlike picking up a bag of popcorn — may be heavy on peat, vermiculite, and perlite and lacking in the nutritional matter that plants need to stay healthy. Your best bet is with a bag of soil that feels “just right” for its size. These mixes tend to have a decent balance of nutritional matter and gritty ingredients to help prevent compaction.

When your choices are between a mix that is too heavy or too lightweight, opt for the light and make your own additional amendments based on nutritional need. I find this option is better because you control the source of organic matter i.e. compost, manure, etc. If you do not have compost at home and have to buy this product too, I would opt for vermicompost over any other type. It is lighter weight (avoiding compaction) and I find that small, local, vermicompost brands tends to be more trustworthy (again this is a very general rule-of-thumb, but I’m talking here about when you’re at the store and don’t have the ability to research).

Choosing seed-starting mix: Look for a brand that says it is for seed-starting specifically. Regular potting/container soil ingredients vary wildly and often contain large-sized bits and pieces that can hinder seedlings from pushing up to the soil surface. Seed-starting mixes also tend to contain more moisture-retaining ingredients, yet are light and airy to increase drainage. This is one area where the “3 Bears Method” does not apply. Many brands now include mycorrhizae fungi in their mixes. I think this is a good thing, but I’m a bit worried about how these soils are stored so prefer to add my own.

What about brand name pellets and compressed pots? Don’t do it. They’re more expensive than a bag of seed-starting mix and you can use just about anything from the recycling bin (as long as you add drainage holes) as a free pot. Pellets and paper pots dry out quickly and I find that they tend to swing between either being too dry or too wet, which is a recipe for plant stress and disease. I find them useless for fast-growing plants like tomatoes that need to be moved to a bigger pot in no time. Save the step and just start the seed in a pot.

Potting Soil Alternatives:

It may seem daunting, but preparing your own mixes is rewarding and cheaper in the long run. The tricky thing for small space gardeners is often in finding a place to store the overflow. Believe me, I get it. I have a basement and a shed now, but I gardened for years without storage space of any kind. In that case I suggest buying smaller bags of individual ingredients. Mix them up in a sealable bin and store it wherever you can. In my case that meant out in the open so I opted for the nicest looking container I could find. Keep it sealed. I once found a raccoon sleeping in mine!

All you need really are two basic mixes: a seed-starting mix and a basic potting soil that you can amend based on the needs of individual plants.

Basic Seed-Starting Mix

1 part sifted coir or peat
1 part perlite (best if you can find a fine grade)
1/2 part vermiculite (I used to use 1 part but have started using less).

You can add a bit of sifted and sterilized compost, or vermicompost to this (no more than 20%) or wait until the seedlings have produced their first set of true leaves and start to scratch a small amount at a time into the soil surface. I have started experimenting with mycorrhizae added to my mix, but can’t report on that yet.

Basic Potting Soil

2 parts coir or peat
2 parts sieved compost
1 part course sand (builder’s. Make sure it is free of herbicides), grit, and/or perlite
1 part vermiculite (optional, but I like it for water absorption)

You may need to add nutrition based on the type of plant you intend to grow in the pot. I do not add it to the basic mix so that it can be amended further (with more grit) to make potting soil for herbs, cacti, and succulent plants that do not require as much soil nutrition. This page from the National Sustainable Agriculture Information Service can help further in choosing the right organic nutrients for your mix.