Monday, April 15, 2013

What is the best seed raising mix?

For any new followers, I decided to conduct a seedling raising experiment to determine a reliable, simple, cheap and efficient method. Well the first set of the results are now in. One of  the methods I was testing was to first germinate the seeds in a seed raising mix before transplanting them into pots. As part of this I have been testing 3 different seed raising mixes. Other terms for it are 'seed starting' or 'germination' mix.
  1. 1:1 Cow manure & Sand. The cow manure is semi-composted commercial brand.
  2. 1:1 Peat & Sand. The peat is fine grained coir fiber (coconut husk).
  3. 1:1 Horse manure & Sand. The horse manure collected from a stable and crushed.
So which one performed best?

The three mixes were placed side by side in a single polystyrene container with the sides cut down to prevent overheating. I drilled a set of holes in the side for drainage, about 5 millimeters up from the base. This would allow a shallow pool of water to form at the bottom, with a hope that it would better maintain the moisture level. I watered using a spray bottle. The container was kept under shade cloth at all times in a sheltered part of the garden. Maximum temperatures ranged from about 20 to 30 degrees celsius, mostly dry with a few spots of rain.

Four variety of seed - Broccoli, Lettuce, Beetroot and Spinach - were planted at the same time, ok within 15 minutes, on the 29th of March 2013 into each mix. Planting was quite quick and easy. I made a trench with my finger, sprinkled the seed in, then nipped the trench back together with my finger and thumb.

5 days later on the 3rd of April the first signs of life could be clearly seen in the horse and sand mix.

The peat and sand had a reasonable amount of germination.

But the cow and sand was well behind with only a few signs of life just starting to show. So off at the gate it was horse, closely followed by peat, but with cow off to a poor start.

16 days later on the 14th of April I could start to see a second set of leaves forming on some of seedlings and decided it was time to transplant them on into some real soil. This is what they looked like at this point:

Horse and sand had done really well, particularly with the lettuce. Looks like a mini-farm, don't you think?

Peat and sand, despite a slower start, had done nearly equally well. The lettuce was a bit behind that of horse but the broccoli had done better.

But poor old cow and sand not only was running behind but had a very poor germination. My conclusion to this is that the cow manure I had purchased from the store was semi-composed and not equivalent to the dried horse poo I had collected. I would suspect dried crushed cow pads would work equally well as the horse poo. But that I will have to test.

Still why the cow manure didn’t work is a good question. My guess is that composed manure is too rich for the germination stage and baby seedling. In the first few days a seedling only requires moisture to grow. It could probably be compared to feeding a baby human on beef vindaloo.

The WINNER is - Dry crushed horse manure and sand.

But wait there is a twist to this story...


  1. Very interesting. Thanks for sharing. I imagine, though that if the horse manure wasn't heat composted that quite a few weed seeds would germinate. Did you find anything like that happening?

    What sort of sand was it? Builders sand? Beach sand?

    1. Would you believe... No weeds. I was surprised by that too. There was a little mushroom growing though.

      Sorry I should have mentioned the sand I used. It is river sand. It is least sharpest of all the sands, thus gentle on the seedling roots. It took me along time to find until I discovered they use it in kids sandpits, probably for the same reason. You can buy sandpit sand in bags from hardware stores.

  2. An excellent experiment! Thanks for posting your results. I have to say I tend to use a standard seed raising mix, but you have made me reconsider.

    1. I have always used a standard mix too, that's why I though an experiment was in order. Pleased to hear my results are challenging your current ways.

  3. Hi Jason

    Good to hear the results. Interested to hear the twist.

    I have a question about mulch. I got some pea straw, and sure enough, the peas are coming up. Can I leave them and then compost them, or should I pull them out when they are little? So glad to get that rain today.

    Thanks, Geraldine

    1. I hope the anticipation of the twist hasn't kept you awake at night;-)

      Re the pea straw, sure you can let them grow, they won't hurt, but unlikely to yield any peas. Commercial seed is often hybrid variety and yields only once. So a better option would be to pull them out and sprinkle some pea seeds that will be both edible and compostable.

  4. Thanks Jason. Someone suggested I could eat the pea shoots, which I am planning to try. The internet suggests salad or stirfry.


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