Do you sterilise Seed-raising mix?

I have just bought some expensive rare seeds (passionfruit, pawpaw etc.) that can months to develop, and it is recommended that I sterilise the seed-raising mix.  My usual theory is to use compost and soil on the theory that it already has a good balance of microbes and the bad ones can't get out of control.  It usually works fine for fast growing veges, but I am not sure about this case.  

How many of you sterilise your seed-raising mix?

If it helps to reassure you, I sprouted Paw Paws, Persimmon, Oak, etc in pots that ended up growing successfully in some home made stuff that consisted of a few handfuls of sifted decomposed wood chips, forest soil, and clay-ish topsoil all from the land I'm at - no sterilize as I follow the same thought process as you about the microbiome.

I've also unsuccessfully sprouted Paw Paws and others this way! So who knows!?

Are you able to sterilize some and "feralize" (haha) some to see what happens?

No sterilization for me, because I believe that plants need microbes in order to grow properly. The beneficial microbes live inside the plant. The sooner they get established, the better the plants grow.

As per my knowledge, sterilizing is usually necessary only for slow-growing seeds to shield them from harmful fungi or bacteria. Seeds that take longer to germinate might just need this extra care.

I want my plants to grow with microbes not instead of them.

I am also of the camp of not sterilizing.

I'm going to be real with you, for me personally I don't see tangible benefits from the extra work. I like to think that my additions of compost and worm castings to seed starting mix creates a nice wide range of microbes to help get the plants established but I don't have cold hard facts to back it up. Just my experience.

I like to start my seeds outdoors so not sterilizing of the soil for me.

If I were starting them inside I would use a commercial product for the soil and assume it would already be sterilized.

Hi Annie,
I'm going to buck the flow... just a little bit.

Do I for my seed starting? No

Should you consider it for these seeds? Maybe

Out in the wild, generally speaking, the microbes have had a chance to settle and even out. That way the good ones can connect with a seed right away. But if you are going to start them somewhere not normal... say in a house or in a greenhouse, then you are changing the rules and it might create an environment for the bad microbes to explode. If you have a small cup of water, it is easy for that cup to get too hot or too cold, because it is just a little amount. But a lake takes much longer to change because of its size. I would suggest the same is true of soil. A small amount in a pot would be much easier to get out of balance than a whole garden. It might not hurt to try some sterilized mix. If I were in your situation, I might take half and half and see the difference. Taking lots of pictures and posting them here on Permies of course :)

I used to sterilize the mix when we first started on the transplants trade , 30 yrs ago.  I found that three main points govern the success of a tray of starts, 1. media contact, the grow media must be fine enough to permit great seed contact, 2. moisture, the media must retain moisture but still drain well, 3. warmth nothing impedes germination and invites disease like cold grow media, every seed packet these days has a germination temp range printed on it, hit the range in the middle no problems. I design and created our own compost based media 20 + years ago, its an evolutionary, results based process but doesn't negate the attention to detail needed for healthy plants.  I start everything in the greenhouse using a combination of heat mats and heated cabinets

There won't be much to live for the 'bad bacteria" when the seed is resting. So there won't be that many... But the plant has all the good bacteria in and on the seedcoat that the mother plant transported from it's rootsystem to immediately start working with, when the seeds pop roots.
Sterilizing it will do more bad than good I think.
You could sterilize the soil, but that will leave a lot of food for explosive growth of fast multiplying species, leaving the seed awash in those.
Better to have a healthy balanced soil. Maybe add some sand to your mix not to have it sit in water too long, creating anaerobe conditions which favor destructive bacteria growth.
And I really like the previous suggestion of speeding up germination by warmth.