How to Make Your Own Seed Starting Mix

Save money on starting seeds

Basil seedlings
Image by Chris Winsor / Getty Images

If you are a small farmer or want to grow a lot of plants from seed, buying pre-made seed starting mix can get a bit pricey. You want a quality seeding mix, but you don't want to spend a fortune. That's why many small farmers do not buy pre-made seeding mix. If you can buy the primary ingredients in bulk, it's easy to make a seed starting mix and not spend too much money on it. The best part is that you can tell exactly what is going into your seed starting mix, which is ideal if you are an organic farmer.

Why Make Your Own Seed Starting Mix

It can be much easier to buy large amounts of the essential ingredients for seed starting mix than buying it already made. And you can use your compost to make seed mix—screen it first by passing it through a framed screen fitted over a wheelbarrow or other large container to sift out large particles, rocks, or other foreign material. Composting on your farm can save you a ton of money if you previously bought compost to amend your soil.

The other main reason small farmers choose to make their seed starting mix is the same reason they start from seed: to have control over the mixture and, ultimately, their food. Making your seed mix gives you more control over what goes into growing your crops versus buying a pre-made blend. Eventually, you may want to customize the ratio or add other soil amendments, depending on that seeds you're planting.

Tip

Transplanting a seedling into the ground can be stressful for the plant. Compostable seeds pots allow for an easier transition. Plant the compostable seed pot in the ground where the growing plant will live in your garden. The natural fibers from the pot biodegrade, allowing moisture and air to get to the roots that can grow past the container. Using biodegradable pots eliminate the need to discard plastic pots. 

Creating a Seed Starting Mix


What You'll Need

Equipment / Tools

  • Wheelbarrow or large basin
  • Garden trowel, hand shovel, or spade
  • Watering can or fine misting sprayer
  • Large container with an airtight lid
  • Gloves

Materials

  • Four parts of screened compost
  • One part perlite
  • One part vermiculite
  • Two parts rehydrated coir (follow directions on the label)

Instructions

This basic recipe for an indoor seed starting mix can be customized, sized up or down, based on the amount you need. Whenever you are working with soil or compost, wear gloves.

  1. Mix Ingredients Together

    Mix in the compost, perlite, vermiculite, and coir in the wheelbarrow or bin. You can make as much or as little as you want. Some prefer working with "parts" terminology, or others prefer fractions: The mix is 1/2 compost, 1/8 perlite, 1/8 vermiculite, and 1/4 coir.

  2. Moisten and Blend

    Moisten ingredients well, then blend thoroughly using a hand shovel, trowel, or spade in a large container, such as a wheelbarrow.

  3. Balance the Moisture and Drainage

    When making your mix, aim for something that balances moisture and drainage. If seedlings are too wet, they may suffer from damping off, a fungal disease that causes them to wither where the stem meets the soil. When this disease afflicts seedlings, they eventually fall over and die.

    If you need a mix that drains more easily, use less compost and more peat moss or perlite. If you are looking for a mix that holds more water, add more compost or vermiculite proportionally.

  4. Store in an Airtight Container

    Whether you make your seed starting mix or buy a commercial soil for starting seed, store your leftover soil in an airtight container to avoid attracting bugs.

What About Peat Moss?

Peat moss was used for years as an additive for soil mixes, because it absorbs and retains water and nutrients, prevents soil compaction, it's sterile, and it's acidic (great for acid-loving plants). However, it has a major downside: peat moss is a non-renewable resource, and it best serves our planet remaining in peat bogs to combat climate change. Use alternatives in place of peat moss, such as compost, coconut coir (coconut fibers), pine bark, PittMoss (recycled paper pulp), and worm castings.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Damping-Off. Utah State University Extension.