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How To Create The Perfect Homemade Seed Starting Soil With 4 Ingredients

Creating your own homemade seed starting soil is not only easy, but can also help to provide young seedlings with the nutrients and structure they need most to develop strong, healthy roots. And all while helping to save on your budget too!

One of the biggest mistakes gardeners make is to start their seeds indoors with the wrong soil mix. To be effective, seed starting soil needs to be lightweight, full of nutrients, and drain extremely well.

Unfortunately, topsoil and even garden soil are not the best choices for starting seeds indoors. They are simply too dense and heavy to allow for good germination or absorption of nutrients into the roots of plants.

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Heavy soils tend to hold excess moisture in, often causing young seedlings to rot below the surface level. And if the seedlings do survive, they often lack the proper root development and structure needed to thrive once being planted outdoors.

What About Potting Soil

At this point, you might be wondering if potting soil might be the answer. After all, potting soil is definitely lighter that regular garden dirt and topsoil. And, depending on the brand and type you choose, it can even contain a bit of fertilizer too.

Potting soil, with its lighter structure and density is certainly a good starting point to create an excellent seed starting soil. But not the total answer.

Potting soil still tends to be heavier than what seedlings need to both sprout and develop strong root growth. In addition, the fertilizers they often contain are usually meant to power more mature plants. Because of this, they and not always easily absorbed by tender, young seedlings.

But here’s the good news. By adding just a few additional ingredients to ordinary potting soil, you can easily turn it into an incredible homemade seed starting soil.

How To Make Amazing Homemade Seed Starting Soil

Although there are a few good seed starting soil mixes available commercially, they can be quite pricey. But by mixing together 4 simple, all-natural ingredients in equal amounts, you can easily make your own right at home.

how to make seed soil
By adding together 4 all-natural ingredients together in equal portions, you can create a powerful homemade seed starting mix. It is not only lightweight, but full of the slow-release nutrients seedlings need.

Not only will making your own mix save you a bit of cash compared to the store-bought brands, it also allows you to create a 100% organic mix. And that can certainly be helpful, especially when growing vegetable plants from seed.

Here is a look at the 4 ingredients, and how they work together to create the perfect homemade seed starting mix.

#1) Potting Soil

Potting soil is the perfect base for creating a rich, healthy seed starting soil mix. Start by selecting a high quality all-purpose potting soil. Be sure that it does not include any fertilizers in the mix, as they can actually hurt young seedlings more than help.

Young seedlings require a lighter, slow-release fertilizer to allow for slow, even growth. If too much fertilizer is present, it can lead to plants with excessive early foliage growth, but weak stems. Unfortunately,too much fertilizer too early can also be fatal to young seedlings.

On the other hand, if the mix includes a bit of perlite, that is more than okay. As you will see next, that is exactly one of the natural ingredients you will be using.

#2) Perlite

Perlite is an all-natural substance made from volcanic glass. When exposed to extremely high temperatures (1500+ degrees), perlite puffs into an airy, lightweight substance that looks quite similar to bits of white styrofoam. And is it ever a helpful ingredient for making great seed starting soil!

Perlite not only lightens the weight of soil, it also helps create air channels that nutrients and water can pass through. It improves soil drainage, and helps young roots to grow more easily through the channels in the soil.

Perlite lightens the soil weight tremendously, all while creating air channels in the soil for water and air. Both of which are vital to strong seedling growth.

Perlite also never breaks down, so it keeps the soil from compacting together permanently. Perlite can be purchased in bags, and will keep indefinitely. Product Link : Espoma Perlite 8 qt. Bag

Compost – Finely Screened / Aged

Finely shredded compost is a critical ingredient to a healthy, powerful seed-starting mix. Compost not only helps to lighten the soil mix even further, but it improves the overall drainage of the soil as well.

Compost is overflowing with nutrients that are easily absorbed by tender roots. In addition, compost can hold in excess of 10 times its weight in moisture,. Talk about a perfect ingredient to help keep tender seedlings hydrated!

Be sure to use finely screened or pulverized compost to keep your seed starting soil fine and loose.

Worm Castings

The 4th and final ingredient to the mix is worm castings. Worm castings are the true power hero of creating a perfect seed starting mix.

The light, airy makeup of the castings helps to break up and lighten soil much like perlite does. But with one big difference. Worm castings are filled with a bevy of trace minerals and nutrients that can easily and quickly be absorbed by seedlings.

worm casting soil
Worm castings are the ultimate slow-release fertilizer. They are perfect for powering young seedlings with a slow, steady diet of nutrients.

These nutrients are slowly released over time and leached into the soil as they break down. Much like with compost, worm castings act as the ultimate slow release fertilizer for young seedlings.

Although you could use just compost, perlite and potting soil – worm castings take homemade potting soil to another level. One that will have your plants strong and healthy come transplant day! Product Link : Pure Worm Castings

A Few Final Thoughts

Creating the mix is as simple as combining equal parts of each of the four ingredients. It is usually best to premix all four in a large wheelbarrow or 5 gallon bucket, and then fill your seed trays.

For best results, always be sure to water down your soil in the trays a few days prior to seed planting day. This will help to provide good moisture in the soil for better germination. It also allows the soil to level off from settling, with time to top off the mix on seed planting day. For great plans on a DIY floor or table top seed starting stand, see : 2×4 Seed Starting Stand Plans

So make this the year you create your own seed starting mix, and grow the best plants on the block! For more information on starting seeds indoors, be sure to check out our article The Secret To Starting Seeds Indoors.

This Is My Garden is a website dedicated to spreading the love and knowledge of gardening around the world. We publish two new garden articles each week. This article may contain affiliate links.