You need to make sure that the soil in which your seeds are going to be planted is fertile, contains the right balance of nutrients, and has the proper pH balance to provide those growing seeds with a healthy environment in which to grow. To do that, you have to find the right seed starting potting mixes.

The good news is that most seeds contain all the nutrients needed to start growing. You won’t need to look for special nutrient-rich seed starting soil right away–not until you transplant the seedlings. Only once the first leaves begin to grow on the seedlings will you need the special soil. For now, stick with a soil that offers:

• Plenty of air space, ensuring the seed and the newly-sprouting roots have plenty of oxygen to grow. Air space also ensures proper humidity and water absorption in the soil.
• Proper moisture. Your plants need a lot of water to grow, so you want to find seed starting potting mix that holds moisture properly.

Also, look for soil that is free of toxic substances and weed seeds. You shouldn’t use the soil from your garden, especially if you have sprayed chemical herbicides, fungicides, or pesticides. The chemicals in the soil will kill the seedlings before they have a chance to grow. And, of course, there are lots of weed seeds in your garden soil, and those weed seeds may steal the moisture and nutrients needed by the seeds–stopping them from growing. This is why it’s always best to buy a fresh batch of soil when you are going to start seeds. That way, you can be certain that the soil is free of weeds and any toxic substances, and that it is just the right consistency to promote healthy seed growth.

One very popular mixture for healthy potting soil contains:

• 1 part compost (great for feeding the seeds)
• 1 part perlite or builder’s sand (the larger particles ensures better airflow and water run-off)
• 1 to 2 parts freshly bought gardening soil

By mixing these ingredients, you’ll make the perfect soil to start your seeds growing.

If you’re going to buy a seed-starting mix from the gardening store, look for soil that is labeled as “seed-starting mix” and not “potting soil”. And, of course, don’t forget the fertilizer–seaweed or fish fertilizer, compost tea, or some other organic seedling fertilizer.

Recommendation: Espoma Organic Seed Starting Mix. Unless I am making my own mix or have some soil from another gardening project, this is my go-to seed starting mix. It’s organic, has mycorrhizae to promote root growth, and works perfectly for almost any plants you need to start indoors.

An excerpt from “Essential Seed Starting Equipment“, courtesy of Epic Gardening.