potting soil recipes
There is no one right recipe when you blend your own potting soil. Each plant type, container location and weather region may prefer a little different mix. In time you will adjust some of the basic recipes to suit your own needs. There are literally hundreds and hundreds of different recipes available on the web. If you start simple using ingredients that are easily available to you and meet your basic plant needs, over time you can experiment.
Compost will not only add nutrients to your potting mix, it helps to neutralize the acidity of peat or coir. For recipes that do not include compost you may want to add a half ounce of dolomite lime (which is alkaline) for each gallon of peat.
Seed Starting Potting Mix
An appropriate mix of material is pretty important for starting seeds. You do want the soil to retain moisture, but soil that remains too moist may cause fungus to develop and your seedlings to damp off. The mix should be fine but light and air filled, allowing tiny new roots to spread and grow quickly. And of course a little basic nutrition for the plant to grow strong.
4 parts screened compost
1 part perlite
1 part vermiculite
2 parts coir
If you are using your own compost you should avoid adding anything that may introduce seeds. If my compost doesn’t get hot enough I get cucumbers and tomatoes sprouting up. And coir is good at moisture retention, so for seedlings that are prone to damping off you can substitute peat moss. Slightly moisten your ingredients to help keep the dust down and aid in mixing, and mix thoroughly in a wheelbarrow or wide pan.
If you are not using compost, try this basic seed starting recipe:
1 part perlite
1 part vermiculite
1 part coir or sphagnum peat moss
Basic Potting Mix
6 parts sphagnum peat moss or coir
1 part perlite
1 part vermiculite
If you prefer to add nutrients to your mix:
2 parts screened compost
4 parts sphagnum peat moss or coir
1 part perlite
1 part vermiculite
A good place to find potting mix recipe information is your local University Extension Service or local garden groups. Local sources have developed recipes specifically appropriate to your region, considering regional moisture and humidity levels, easily available ingredients and so forth. Especially if you want to add garden soil to your mix, the locals know if the soil in your region is good and loamy for a mix or if it generally has too much sand or clay.
Start simple and get growing!