Growing seeds in home made potting soil?

[tenar]

Hi all,

I'm brand new to the forum, have some questions, hope someone can help! I'm in Melbourne, Australia.

I am experimenting with home made potting soil. I used roughly:

1/3 worm compost (from our own worm farms that we use to process vegetable waste from the kitchen: usually I spread this as fertilizer on any/all of my plants.
1/3 coconut coir (with water added etc)
1/3 vermiculite.

Mixed it all up, looks great, etc.

Since I don't want to test it with expensive plants, I'm trialling it with growing some seeds I had to hand (things I want to plant now anyway). So I made myself two sets of containers: one with my potting soil and the other with a commercial mix I usually use.

In one pair of containers I planted some broad bean seeds.
In the other pair of containers I planted some rainbow chard seeds.

I was cheerfully hoping to see luscious and amazing growth from the home made mix, because why not dream... It's been about a week or two. I now have some broad beans sprouting and some of what I guess is rainbow chard sprouting. However unfortunately the sprouting things are in the commercial mix, not mine. Nothing sprouting in my mix at all, as yet.

Has anyone had trouble getting seeds to germinate in their own home-made potting soil using vermicompost? I'll be a bit shattered if this stuff turns out to be toxic to plants... I can't see any reason why it would be.

 

[DirtMechanic]

What soil would the seeds naturally germinate in? You have focused a lot, a bunch, in a growth medium. Maybe just warm them? I do not know the specific gravity of the 2 mixes but the denser a material, the more ambient energy it takes to change temp. What do they weigh for any given volume you choose? Anyway temps make more of an impact in the spring than I realized so just trying to share the germination temp idea

 

[Tetters]

G'day Bruce (aka @tenar ) .....welcome to the forums, it's good to have you on board.

That sounds like an interesting experiment. I'm wondering if the worm compost might be a bit rich for seedlings - which don't actually require any feed in order to germinate. The other two ingredients mixed with some ordinary sieved soil might work though - worth a try maybe.
I can't think of anything in your worm compost that could possibly be harmful to plants, and am wondering if you have used this stuff to grow anything on in?
Please do keep us informed about how the experiment proceeds - very interesting

 

[NigelJ]

Those seeds you mention take a while to germinate. You could try something fast germinating like cress, mustard, radish or similar.

 

[tenar]

Thanks all, and g'day yourselves

I don't think temperature is the issue. Melbourne has a temperate climate, ranging from minimums of about 5 degrees C to maximums of low 40s in high summer. It's autumn here now, mild weather (maximums in the low 20s Celcius, minimums in the mid teens, so something like 60-80 degrees F through the course of a day. And of course the seeds I planted in the commercial potting mix are germinating, so if they can do it I'd hope my own mix would do it too...

I have wondered if it might be too rich for them, though I'm not sure if that would manifest in a failure to germinate or problems further down the track. I'm not sure.

I don't have sieved soil, unless I buy some. I have a terrace garden: everything is in pots, which is why I'm interested in home-produced potting soil, as I use a lot of the stuff (also I reckon, at least in theory, that I should be able to do it better!).

I have used the worm compost as a fertiliser for years without obvious problems, and mixed it through the existing potting soil of all my pots when I change the plants in them. This is the first time I've attempted to make "proper" potting mixture from scratch with structure in the form of the vermiculite/coir as well as the compost. Certainly heaps of things sprout from the compost all the time: the seeds the worms don't eat end up as weeds the following year, which is a whole other issue, but not a major problem to me: I just pull a million baby tomatoes and pumpkins out from everywhere.