Making Your Potting Mix
1 part wet wood stove pellet (make sure its pure wood)
1 part fine pine bark
1 part peat moss (optional) can substitute coconut coir instead of peat
1 part coarse sand
For a starter soil you want something fine and light. You also want to have something that doesn’t dry out too quickly. It must have enough strength to hold the plants roots together as well. Starter soil is available at most greenhouse supply and home and garden centers but its easy to make. If you grow lots of plants its better in our experience to have a supply of different types of media on hand to mix tailor made potting soils. Its cheaper and its easy.
The main ingredients to most any potting soil is something to hold moisture in and commercially to be light so that handling and trucking weights are kept down. Mixing sand in isnt normally done for most greenhouse grown plants. At home it doesnt matter so much because you arent moving them around nationally by truck. Since theres no compost, theres less chance of fungus, disease, or weeds.
The sawdust holds water and although it takes more carbon than other ingredients its cheap and light. You will be starting the seeds and fertilizing them in a mixture of other ingredients as well. The fine pine bark helps water retention and aerates the soil. Peat moss has anti fungal properties, and sand creates strong roots and aerates the mix. Since it is a soilless media there is a greatly reduced risk of introducing pests and disease from dirt taken from elsewhere. Its a win win for you and your plants.
The pine bark holds tiny little air pockets in the soil so that your plants roots get plenty of oxygen. Pine generally doesnt break down very fast. You dont want something that will pack down and turn to mush. Like the sawdust, pine bark also holds water but drains well.
Peat is sometimes a touchy subject for some as it isnt always collected with the best ecological interest. If you choose to use it in your mix it will produce a lighweight soil. It will hold water well and will drain well.
As the last cheap ingredient we have sand. Coarse sand is best. You want the sand to make tiny little air pockets so your roots can enjoy some oxygen. It prevents it from packing down and also holding too much water.
You keep hearing the word drainage. Drainage is very important. It is as important as the water holding capabilities of the pine bark, sawdust, and peat moss. You want it to retain water for a long time but you dont want it to be soggy. Drainage is very impiortant because holding water will kill your young plants and create breeding grounds for fungus and disease.
Vermiculite, perlite, and other similar ingredients are good but they are costly. They are also sometimes hard to find and just not necessary for the home gardener. We quit using it altogether. There is supposedly no longer asbestos in the new mining areas and they test it. In the past some have strayed away from those types of media from fear of asbestos.
Fertilize with a basic fertilizer after they start growing their leaves as there is no nutrients in the soil mix. There’s really no need to have nutrient to start with as the seed is an embryo. Mix an all purpose fertilizer of your liking and feed them with that a few times a week once they get growing. There are certain types of fertilizers that will help compact growth so they dont get leggy and spindly.
Professional nurseries use a growth chemical mixture to purposely produce those compact little plant starts. In Washington state you need an applicators license to buy it. We use fertilizers to get the same result. We will elaborate on that in a later article but its something to consider when wanting those compact and lush plant starts come springtime.