This is the season for seedlings. Now is the time for germinating them in your home or greenhouse, which of course requires good seed compost. The problem is most compost types (including multipurpose compost) you can buy from garden centres and nurseries are not ideal seed starting mixes. You have probably had some plants that no matter what you did, just did not germinate. They seemed overly watered on top but dry to the bones down below.
The cause? If the compost mixture isn’t right, it can lead to bad water absorption, something that proves fatal to your new seeds because they can rot before they start. If the nutrient content is wrong, it will hinder root growth and seedlings need very little nutrient value at first.
Plus, it’s expensive. No matter where you look, high-quality compost is expensive.
To that end, knowing how to make seed compost for starting seeds can prove very useful, especially if you are going to germinate from seed, season after season.
The perfect recipe for germinating seeds
To make anything, you need the perfect recipe. The seed starting mix needs to be low in nutrients, hold onto moisture without becoming soggy, and it needs to be light and fluffy so the roots can penetrate and spread without much resistance.
Getting the base mix right
Start with the base of your mixture should contain two parts of compost. When reading this compost mix, be advised that the parts are based on volume, so whatever amount you are making, you can keep to the same volume and ratio. We recommend just using a large jug to scoop the correct amounts in equal volumes.
Use 2 parts compost that has been sieved with a riddle
Compost will release nutrients slowly, something the growing seeds need. Break apart the compost with your hands, but we do recommend using a compost riddle to make it as fine as possible.
Mix the compost with 2 parts coir
Mix in two parts coir, or coconut fibre. This is what often lines store-bought wireframes for hanging baskets and it is a great alternative to peat moss, and we are always trying to find good alternatives to peat to do our part to help the environment. While peat moss is the normal additive here, it is not a sustainable product to use while coir is, which is why we recommend it.
If you order coir and it arrives in a block form, you need to rehydrate it in a bucket of water until it breaks apart.
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Finally, add one part of perlite to the mix
Lastly, add one part of perlite to improve air content and lighten the mixture. Sand is an alternative to perlite, but it will produce a heavier mix.
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Mixing the compost mix
When you have all your ingredients, you need to mix them thoroughly. Use your hands for better tactile engagement and thoroughness; the more consistently mixed the better. When you are done, store your mix in a lidded container or thick plastic sack in a cool, dry place.
Germinating seedlings
When it comes time to use your homemade seed mix, moisten it so that it is not too sodden, but not too dry either. Use recycled containers, seed trays, or module trays and gently press down on the mixture as you fill your container of choice. Consider using a heated propagator to improve the germination rate and speed up the process.
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Be sure to sow the seeds according to your packet instructions and water afterwards. Rest assured this mixture can be used as you transplant young seedlings and is something you can make year after year.
Would you rather buy seed compost?
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Last update on 2026-07-22 / Affiliate links / Images from Amazon Product Advertising API
