My seed starting mix is steril right out of the bag I do not add anything till I "pot uo" rate of growth is more dependent on light, water, ground temperature& less on adding fertilizer.
I prefer a short/compact plant to one that is leggy

I agree about providing the light that will prevent legginess.

I'll add one interesting bit of info, at this point.

I was disappointed in the results of planting seeds in sterile commercial potting soil... EXCEPT in the case of a few trays where I mixed about 15% volcanic-rock powder in with the potting soil. Jeepers! the seedlings in those trays grew twice as big and twice as healthy in the same period of time as some in trays for comparison. In the comparison trays, I used the same commercial potting mix, the same seed, the same light and the same watering schedule & technique - just no crushed volcanic rock.

Adding the volcanic rock did not add fertilizer, but it did improve the porosity and the air in the mix. To me it seems obvious that your bagged mix holds too much water and excludes air. If you are going to buy a bagged mix I would look at another brand. Al

calistoga, thanks for replying.

I'm not sure that the bagged soil is too exclusive of air and too retentive of water. It contains a fairly significnt proportion of perlite. But it was pretty clear that the bagged potting mix did not offer much in the way of nutrients.

In my assessment, the volcanic rock powder that I used wouldn't seem to be as good as the perlite in terms of keeping the soil loose, hence in aerating the soil. Because it is a very fine powder (very much finer than sand).

I tend to feel it's some other property of this amendment that is responsible for the pronounced difference in the health and development rate of the seedlings.

As time goes on, I'm more and more interested in the crushed volcanic-rock that I mixed in with some experimental trays of seedlings. The difference in results was so startling!

Anyhow, my problem is that I'm not sure how to source more of it. The company that sent me the sample seems to be dormant, and - as they were a new company - I fear that they've run into financing challenges or something.

So I'd like to find other sources, brand names, etc. Have any to share? (I'm in western Canada, but some products sold in the west and northwest of the U.S. are also sold up here.)

Another question that I have, because I'm so new to using the volcanic-rock powder: are all volcanic-powders essentially the same in their effectiveness, or are there significant differences in terms of how they enhance plant growth?

Gardening is really all about trial and error. What works for one may not work for others. There are many factors that one must take into consideration. Have you ever tried to grow seeds in milk jugs outside in the wintertime? Sure beats worrying about them inside. Look at member's pictures of their flowers; there is a forum of members who grow inside under the lights setup..if their pictures of their seedlings and flowers appeal to you, send them an email and ask them what they use. Most people will be more than happy to share their secrets to successful planting indoors or outdoors(Wintersowing). Sometimes it is difficult to find products that others find locally, so you have to spend money to order from online sources. Shipping rates can put a crimp in one's budget but sometimes there's no other way.
I would love to try growing indoors under lights, but have no space for it and since we get such glare and reflections from outside on our tv, my husband keeps the blinds closed all day. It drives me crazy to be closed up like that, but when we open the blinds, we see reflections of everything from outside, regardless of where we have the tv in the sunroom. I may try growing some seeds indoors in another room on a tv snack tray, just to see if it will work next winter. I pull my blind up in the office so I can look outside. I can't stand the winters because of the the cold weather but just having to stay cooped inside so much. I need to see people and in the wintertime a lot of people have a tendency to stay inside for whatever their reasons.

pippi21, you wrote: "Sometimes it is difficult to find products that others find locally, so you have to spend money to order from online sources. Shipping rates can put a crimp in one's budget but sometimes there's no other way."

Well, the shipping rates from the place I know of to order the volcanic rock powder are really prohibitively expensive.

Actually, I'm quite surprised that others here have not tried, or even heard of, volcanic-rock powder. If there was enough demand from those of us in western Canada, I'm sure wholesalers and retailers of the product would emerge!

My own small, informal trials are enough to convince me of the value of using the "paramagnetic" volcanic powder. Back in the spring, I was starting several kinds of plants using a bagged potting soil my wife and I bought. I used that "growing medium" unamended, in sets of matched starter trays, except for those trays in which I'd added about 15% volcanic rock powder to the mixture. All those seedlings were started under grow lights. (I didn't take pictures of the results.)

Somewhat over a week ago, I again used starting trays ("six packs") and matched the basic growing medium, the watering regime, and the lighting on the experimental and control trays. However, I made up my own starter medium as follows: 50% sphagnum peat moss; 30% worm castings; 20% perlite - well stirred. This, in itself, is a pretty rich mix because of the worm castings. One of the trays contains this mixture as such. The other has this mixture with about 12% volcanic rock powder stirred into it. I made up only two trays, and identified each one to be able to interpret my results.

With each of the six packs, I filled each of the cells as close to the same level as I could. I planted each cell with two radish seeds from the same packet. I kept the trays on a bench in our greenhouse. Then I was careful to keep the watering and the light exposure the same. Seed germination took about 48 hours, on average - and the germination rate was pretty much the same, comparing the two six packs.

The picture, taken eight days after planting the seeds, pretty much tells the story. The seedlings (on the left) with the volcanic powder in their growing medium are clearly doing better. I'd estimate the difference in vitality and growth to be maybe 20%, at this early stage.
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With my spring-time experiment, the difference seemed more marked - probably because the commercial growing medium was very basic and not high in nutrients (such as those the worm castings provide to the new mixture). With the spring experiments, the seedlings growing in the medium that included the volcanic rock powder did twice as well, in my assessment, in terms of vitality and size. However, I judged this difference not after eight days, but after a month or so.

I was thinking some people who look at this thread might like to see a picture that conveys the benefit. While Paramount Growth Holdings is not yet retailing their product, other sources for this sort of volcanic rock powder in the U.S. and Canada might be available.