Arlene,

I really, really like Pro-Mix for my seeds. It's just peat and perlite, but really overall a simple, clean soilless soil. Depending on what I am planting, I may screen the mix to remove the perlite entirely, or add in more perlite for seeds I think will take longer and I'm worried they will rot in the meantime.

With ProMix and a good spritzer, I find it's just a safe bet. I'm sure there are fancier soils out there for seeds...but of all the ones I've tried, I like this one the most. I keep going to other types to try (for seeds or plants) but in the end, I find ProMix to be the most reliable.

This is Pro-Mix with added perlite that I didn't screen. Being off-season, I wasn't certain how long I'd have to wait for them to germinate, so I added perlite.

Sugi, thanks for the recommendation! Do you add any supplemental fertilizer to your seedlings? On the Pro Mix site, an organic fertilizer is listed in the ingredients for the seed starting mix so I'm wondering if I could skip the regular waterings with half strength miracle grow if I use this.

Arlene - you mean to start the seeds? I don't add anything to the soil in terms of fertilizers.
When they begin leafing out -- like when the second leaf set after the cotyledons and first leaf set have already grown, I'll begin to add a tiny bit of fertilizer to my water bottle, carefully. The seed and seedling shouldn't need any fertilizers to get to that stage regardless of which soil mix you use.

I think each ProMix soil type has different things -- like some have mycorrhizae, others have fertilizer, etc. Right now, I have Promix HP, but I've used some of the others too. When it comes to seeds, my treatment is exactly the same no matter what soil I'm using, so long as it's simple and clean enough for seed growing.

Hope that answers your question. If you try - let me know how it goes! :)

Grace

Arlene - for just starting seeds for transplant out, honestly, any halfway decent commercial soilless potting mix will do. I tend to avoid the ones that contain coir just because I feel the jury is still out on the safety/efficacy of unknown sources of coir; but that said, I accidentally bought some Miracle Gro Moisture Control mix this past spring and it doesn't seem to have killed anything so far, LOL! The MG Moisture Control has coir in it; the "regular" MG does not.

When I used to mix my own, it was 1:1 or 2:1 peat and coarse vermiculite but I haven't been able to lay hands on coarse vermiculite for ages. Apparently, it turns out, the major mining operation/producer of vermiculite shut down in the 90s (I gather there was some scandal involved, over safety or what, I don't know) and since then sources of vermiculite are much fewer and farther between.

Then I was using 1:1 peat and a good garden soil (MG was my choice) - which is OK for seed starting but no great shakes for anything likely to be in a pot for more than a single growing season.

Now I am experimenting with various peat and "other stuff" mixes, including some barks that have been deemed unsuitable for long term mixes (too many fines, etc). For longer term I will be trying peat/pumice and peat/pumice/bark blends but haven't got started on that yet. Today I will be planting some ginger in a 1:1:1 peat/pumice/soil conditioner blend.

My seed starting mix for the coming season will be:

1:1 peat and fines sifted from pine bark
OR
1:1 peat and Scotts Turf Builder - a very consistent but very small pine bark product, with a small component of compost and "forest products" plus a very very small amount of fertilizer (1:1:1)

I will alternate rows in my paks with one or the other, with the same plants planted in one row of each. I will have lots of extra starts to share, I think, LOL!

I have actually started seeds in 100% peat. While there are undoubtedly seeds that won't start well in that, nothing I grew that year turned a hair.

Seeds are generally pretty darn forgiving. I don't think you have a lot to worry about, whatever you choose. I would suggest choosing the option that is most economical for you, whether that is watching for sales of MG or Hyponex or what have you, or going with a mix of your own.