At Seedman Farms, we have been germinating seeds for over a quarter of a century. We germinate everything from the tiniest seeds such as petunias, tobacco and irish moss, to large seeds the size of eggs. Some seeds sprout in a few days, some varieties can take up to two years.

The one constant in these germination endeavours is the seed starting mix we use. We use the same mix for everything. We mix this blend ourselves here on the farm. We have tried every seed starting mix ever offered, hoping find something as good or possible better so that we could better use our time, but so far have not.
Quite often we are surprised at what some consider a seed starting mix, some have bark ( bark? ), twigs and clumpy looking stuff, some just looks like potting soil and is packy.

A good seed starting mix is really very simple, it needs to be a fine mixture with no bark, twigs or anything that would prevent tiny seeds from germinating, it must be loose when wet, allowing air to the roots, it should be somewhat sterile, as in no seeds or disease in it and be conducive to good root growth.

The surprising thing is, this is really rather easy to produce, and we encourage our customers to consider making their own rather than buying it if they can. This saves you money, and is an enjoyable project to undertake.

We start off with only two basic ingredients, sphagnum peat moss and vermiculite. A good blend is about 2 parts peat to 1 part vermiculite. We have customers ask us why we do not use perlite in our blend, the simple answer is that it will often work it's way to the top of the soil during watering, where it does no good. Vermiculite added to the blend increases water and nutrient retention and aerates the soil, resulting in healthier, more robust root systems.
But what you get from garden center is a bit rough, the peat is clumpy and often has bits and lumps, and the common grade vermiculite is too large for use with tiny seeds. We mill ours to a specific size, you can do this with trial and error using a blender ( food processor ) and screen. If you are only starting vegetables such as squash and melons, you need not worry about doing this.

Once you have the peat and vermiculite down to size and grade, blend thoroughly. This is very important. For the best results, it must be blended very well, simply stirring by hand will not do. One way to accomplish this, is to add the ingredients to a five gallon bucket and use a paint mixer paddle with an electric drill motor ( be sure to wear a mask, this is a very dusty process! ). We use a commercial mixer for blending ours ( and it is still very dusty! ).

After the base of peat and vermiculite is blended, you will have a sterile base for your seed starting mix, but you still need to a few things to accommodate the seedlings after they emerge.
We also add a couple of tablespoons of powdered lime to the mix as peat can be a slight bit acidic and the lime counters this.

We also add a bit of Mycorrhizae to our blend. Mycorrhizae ( pronounced my·cor·rhi·za ) refers to a group of fungi which form a mutually beneficial relationship with many plants. These fungi grow either inside of a plant’s roots or attach to the surface of a root. The fungi benefits from the plant’s food and nutrients and in turn send their hyphae (like small roots) out into the surrounding soil to absorb nutrients and water. Simply speaking, mycorrhizae actually enhance a plant’s ability to take up nutrients and water. Because of this, research has shown that the presence of mycorrhizae also help plants deal with drought and some diseases. Adding this is not really a requirement if you are planting the seedlings directly into the garden or any type of container with garden or potting soil as almost all soils will contain mycorrhizae. But since this is a soilless blend and sometimes customers will plant seedlings into pots containing a soilless blend, it is a necessity to have this incorporated into our mix, plus from our observations, it does seem to make seedlings more healthy at an early stage.
There are so many different brands of this on the market, so it is hard to say what quantity to say to use, but a little goes a long way, so a good rule of thumb would be about a teaspoon per 5 gallons.

The final ingredients we add is a low nutrient charge to the mix that allows the seedlings to grow to transplant stage, and a bit of super phosphate ( 0-45-0 ). We have tested many different types, but really found that a general purpose soluble plant food added in granular form works just as well as any and the super phosphate can be found at about any garden center. We use a 12-15-30 blend with micronutrients that seems to simply work best as far as blending and feeding the young seedlings, but any water soluble plant food should work.
For reference, Miracle-Gro Water Soluble All Purpose Plant Food has a ratio of 24-8-16, which means that it contains 24 percent nitrogen, 8 percent phosphorus and 16 percent potassium, as expressed in the national standard format.
The super phosphate will help encourage good root growth in the young seedlings. Rule of thumb is about two tablespoons of plant food ( somewhat in the 20-20-20 range, but can vary ) and a teaspoon of super phosphate per 5 gallons. You will find small bags of super phosphate in almost any garden center or on-line.

And that is it, follow these directions and you will have great, easy to use seed starting mix for starting all varieties of seed. It may seem a bit daunting to accumulate all of this material, but remember, you will always be needing a seed starter mix, and will save money doing it yourself.

Also, waste not, want not. If you are using small containers to start your seeds in, then you should use all seed starting mix, but if you are planting directly into large containers, then only fill about two inch thick layer at the top of container with seed starting mix.