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Seed starting mix can be expensive to buy, so I came up with my own homemade recipe. This is the best medium to use, and it’s also very easy to make.
In this post, I’ll tell you all you need to know about seed starting soil. Including choosing which type to use, and what properties to look for.
I will also show you exactly how to make your own DIY seed starter soil mix from scratch with only a couple of ingredients, and give you tips for properly storing the leftovers.
Table of Contents
The Best Seed Starting Mix
The best seed starting medium is a soilless mix that’s fast draining, lightweight, aerated, and also holds moisture. You should always either buy a quality brand or make your own using my recipe below.
Trust me, the type of soil you use really does matter – and it can be the difference between seed starting success or epic failure! So read the package to find something with the following properties:
- Well-draining – If the soil holds too much moisture, or becomes overly wet or soggy, it can cause the seeds to rot, prevent germination, or suffocate delicate roots.
- Light & airy – Seed starting mix should be lightweight and fluffy, so that plenty of air can reach the developing roots. Heavy soils tend to become compact in containers, which will inhibit germination.
- Porous mix – A porous medium is loose and aerated. This allows water to drain through it quickly without retaining too much, and also prevents compaction.
- Moisture retentive – It’s extremely important that the soil stays evenly moist for both germination and healthy seedling growth. The mix should retain water to prevent it from drying out too quickly.
- Alkaline – The soil should be alkaline for starting most type of seeds, ideally between 5-8 on a pH probe gauge.
Related Post: Seed Starting Peat Pellets Vs. Soil: Which Should You Use And Why?
How To Make Seed Starting Mix
While there are many different options for commercial seed starting soil on the market these days, it’s usually cheaper to make your own.
Plus it’s quick and easy, and you have full control of what goes into it, so you can ensure it contains quality ingredients. Here’s my recipe:
DIY Seed Starting Mix Recipe
- 8 parts coco coir or peat moss (pre-moistened)
- 1 part vermiculite
- 1 part perlite or pumice
- 1 tablespoon garden lime per gallon (if you use peat moss)
I like to use a 1-cup measure as my “part” because it makes the perfect amount to fill up a commercial seed starting tray. You can use anything you want though, as long as it’s the same thing for each “part”.
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Ingredients
- Coco coir or peat moss – These are interchangeable, so you could use either one as your base ingredient. They both work equally well to improve water retention, aeration, and drainage.
- Vermiculite – This naturally occurring mineral helps the seed starting mix retain moisture, while also preventing it from staying too wet.
- Perlite or pumice – You can use either one of these, they both add drainage to the medium, to keep it from holding too much water or becoming compacted.
- Garden lime – Peat moss is slightly acidic, so you should add lime to neutralize it. You don’t need to use this with coco coir.
Related Post: How To Make Newspaper Seed Starting Pots
Tips For Mixing Your Homemade Seed Starting Soil
Once you gather your ingredients, making your own seed starting mix is very easy. You could whip up a large batch ahead of time, or just a small one when you need it.
Simply dump all of the ingredients into a bowl orpotting tray. Then use a hand trowelto stir them together until they’re well blended. You can use it right away or store it for later.
Related Post: How To Grow Seeds: The Ultimate Guide
Storing Your Leftover DIY Seed Starter Mix
Whether you make your own soil for seed starting, or choose to buy a commercial brand, it’s important to properly store the leftovers to prevent bugs and contamination.
I like to put mine in a plastic bucket with an airtight lid, which works great to keep pathogens out. Store the container in a cool, dry location until you’re ready to use it.
Making your own DIY seed starting mix is easy and economical. Use it right away, or save it for later. You can even use my homemade recipe for repotting your seedlings.
Looking for even more help with growing your own seeds? Then you should enroll in my Seed Starting Course. This fun, in-depth self-paced online course has everything you need to know. Register and get started today!
Otherwise, if you just need a refresher, or want a quick-start guide, my Starting Seeds Indoors eBook is for you!
More Seed Starting Tips
- How To Figure Out When To Start Seeds Indoors
- Tips For Starting Seeds Indoors
- How To Test The Viability Of Old Seeds With An Easy Germination Test
More DIY Potting Soil Recipes
- How To Make Your Own Succulent Soil
- How To Make Your Own Gritty Potting Mix
- How To Make Potting Soil For Indoor Plants
- 7 Easy DIY Potting Soil Recipes To Mix Your Own
Share your favorite recipe for seed starting mix in the comments section below.
Printable Instructions
Yield: A batch using a one cup measure as your "part" is enough to fill one commercial seed starting tray
Seed Starting Mix Recipe & Instructions
This 3 ingredient seed starting mix recipe is easy to make, inexpensive, and the best soil for germination and seedling health. Follow these step-by-step instructions for how to make your own from scratch.
Prep Time5 minutes
Active Time5 minutes
Total Time10 minutes
DifficultyEasy
Materials
- 8 parts coco coir or peat moss (pre-moistened)
- 1 part vermiculite
- 1 part perlite or pumice
- 1 tablespoon garden lime per gallon (if you use peat moss)
Tools
- Measuring container
- Trowel or large spoon
- Mixing container
- Seed starting trays
Instructions
- Pour the coco coir or peat moss, vermiculite, perliteor pumice, and garden lime (if you use peat moss) into a bucket or bowl.
- Mix the ingredients until they are well blended.
- Once mixed together, you can fill your seedling trays and start planting right away.
- Otherwise, store it in a plastic bucket with a tight fitting lid.
Notes
- You can use anything you want for your "part", as long as you use the same measure for each ingredient.
- For example: if you use a 1 cup measure as your part, then this recipe would convert to 8 cups coir, 1 cup vermiculite, and 1 cup perlite.
