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My homemade seed starting mix

You absolutely don’t need to fork out for expensive seed starting soils or mixes from the garden centre. If you need more than a small bag, it’s much cheaper to make your own and it’s very, very simple and needs only a couple of ingredients.

As always there is a video link below to our video on us making our mix and talking about it.

My seed starting mix: https://youtu.be/0ReCOO0H6dc

What is seed starting mix and why make it?

If you have ever bought seed starting mix you might have noticed that that little bag doesn’t cost much really, in the scheme of things. However when you realise that the little bag you bought is nowhere near enough and you need to buy more. It starts to add up.

It might also interest you to read the ingredients list on some of those bags – if they are even honest enough to tell you what’s in there. You might be shocked to find how many chemicals are used to bolster big claims of water retention or fertilisers to aid in boosting your plant’s growth. Which is a waste of money because seed starting 100% doesn’t need any fertiliser at all. A seed is a bit like an egg, everything that little seed needs to germinate and begin to grow is already there inside the seed. It doesn’t need anything else until it starts to get its first true leaves which is usually a few weeks after it germinates. In fact, you only need to give a seed (well most seeds) 3 things in order for them to grow and that’s moisture, oxygen and warmth. Bet you expected soil to be on that list didn’t you?

I said most seeds because some seeds also need light to germinate, but most don’t.

So why bother with a seed starting mix then?

So you would be completely justified in asking now why we bother with seed starting mix if the seed doesn’t need soil at all. It basically comes down to this, as gardeners, when we are trying to grow seeds into plants, we are trying to have the highest success rate we can, so we try to make everything as perfect as we can. That means giving the seedling exactly what it needs and eliminating the things that could reduce success. That will be reducing things that could harm the tiny seedlings like unfriendly bacteria and fungus, pests, disease and even weeds.

So how I make this perfect, safe environment for my seeds and seedlings then… simple, I make a mix that holds moisture but not too much, is light and fluffy so as not to damage or obstruct tiny roots and that is airy to let much-needed oxygen to the plant. And…. I use something that isn’t high in nutrition because for one the seeds and seedlings don’t need it but also over nutritious growing mediums especially chemical fertilisers can actually burn delicate little seedlings.

  1. Spent compost or coco coir is a great moisture retaining growing medium that wouldn’t be too rich in nutrition. We try to avoid buying peat based products and so we usually use spent (used) compost in our mix. Compost is moisture retaining and when it’s already been used, most of the nutrition hs been used up. This is especially cost saving for us as we make our own compost and, that also means we know exactly what is in it. However an alternative to spent compost is coco coir, which isn’t perfect in terms of it’s green credentials when it isn’t local to us, but it is less harmful than peat so I guess it’s about making your own judgement calls on what you want to use and why. I also sieve my compost until it is very fine, I don’t want anything in there that’s too large and could cause issues for very fine plant roots so I sieve to help make it very light and fluffy.
  2. Perlite which is an ultra lightweight volcanic stone, well glass really. Which looks like tiny white pebbles, and as it’s porus it’s excellent for both drainage and aeration.

My Seed Starting Mix

  • 1 part coco coir or spent compost
  • 1 part perlite

That simple. When I sat part I just mean that whatever I add in terms of the amount of compost or coir, I add half as much perlite. That could be a handful, a scoop, a plant pot… whatever measure you have to hand. Now, remember I mentioned eliminating all the potential issues in terms of fungus, bacteria, pests etc? Well especially if you are using spent compost this is really something to think about. Before I use my potting mix, I sterilise that spent compost by roasting it in the oven or outdoor BBQ grill to kill all the nasties off. I actually wrote a blog about this last year:

So once you have all your ingredients ready to use (sterilised if need be), you simply mix it in a clean bucket or tub, add some water to make sure the mixture is moist but not wet and sow your seeds.

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