Seed Starting Soil Mix Recipe

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When you’re operating a plant based homestead, seed starting is one of the most important tasks you do. Because we grow so many plants, I begin my seed starting in January, and will continue through April. Then again in August for the fall garden, and any plants I am overwintering (such as kale, mizuna, broccoli, etc.). Today I am transplanting 150 tomato plants, along with about 100 pepper starts, just to give you an idea of the scope of seedlings I’m talking about.

When you’re starting your plants from seed rather than buying starts, the soil you use is one of the most important things to keep in mind, and luckily, one you can easily control. Many of the soils you can buy pre-bagged are too dense for the tender, tiny roots of new seedlings to navigate. Using these can leave your seedlings stunted, or even keep them from growing at all. There are seedling mixes on the market that are made specifically to deal with this issue, but they can be harder to find and often quite expensive.

I prefer to create my own seedling mix. The recipe I follow was developed through trial and error, but has now successfully grown hundreds, if not thousands of seedlings. In fact, this year we have (so far) had a success rate of 100% germination. 

You need to keep three things in mind when creating soil for your seedlings:

1. They need light, fluffy soil to encourage the growth of tiny roots and stems.

2. They need soil that will hold moisture and not dry out too fast, but also that drains well so they don’t drown or mold.

3. A seed has everything it needs for the first few weeks of its life contained in its shell so there’s no need for compost or fertilizer until the first transplant.

That is really the basis for excellent seed starting soil, and keeping those three things in mind, this is the recipe I use for all of my seed starting.

Seed Starting Soil Mix

1 8 quart bag of organic potting soil

2 blocks of coconut coir

1.5 gallons of vermiculite

Mix those all together and water them very well with warm water. You want the mix to be nice and damp and warm when you plant your seeds because that helps them to germinate quickly. The vermiculite and coconut coif both help to make the soil loose and fluffy while holding in moisture so your plants don’t dry out as quickly. A dry start is a dead start. You don’t want that.

When I transplant my starts to a bigger container, I use the same mixture but add in 16 quarts of compost. You can buy the compost or use your own, but it gives the plants a lot of good microbial life which helps to feed plants by converting organic matter into plant accessible nutrients, along with a good boost of organic material for the microbial life.

Using this seed mix also helps reduce my watering. I only have to water every other day to every three days, depending on the plant size and how close to the heater the shelf is. The added components really help to maintain moisture. With a good start to their soil life, plants are more likely to thrive, giving you the garden of your dreams.