Seed Starting Soil vs Regular Potting Soil for seeds (growing, manure, seeding)

[Cambium]

Was curious what you guys thought or if you experimented with it.

I understand the difference based on what its made of and the benefits... but ... When we direct sow into the ground or a pot we're not using seed starting soil. It's just regular potting soil and they germinate and grow nice.

So is it because they are inside in a seed tray why we can't use the regular potting soil?

[mizar]

Well, it depends on the nutritional requirements of the particular seed you're sowing, as well as the nutritional analysis of the potting soil you're using.

Seeds have enough starch stored to feed them for awhile, and can usually do fine for a week or so on their stored energy. Some seeds with low nutritional requirements will burn when started in a high nitrogen potting soil, and are better off started in seeding mix, then transplanted to a richer mix when they're 2-3 inches tall, or when the tiny round first leaves (cotyledons) start to yellow. The yellow tells you the plant is cannabilising nitrogen from itself, and is an indicator that it needs more nutrients.

Many of the potting soils today are pre-fertilised with artificial NPK, which is a shock to sensitive-type seeds/seedlings. In the garden your soil is usually initially organic, and gentler to the young plants.

[Submariner]

We use the same soil mix for both applications.

I dump out last year's containers into a wheel barrel. I shift through it to break apart any root balls, and to remove any debris. Then I 'adjust' it according to what I am seeing. I may add either; sand, or peat, or both. After that is mixed and I am happy with the feel of the soil, then I add compost.

I use this soil-mix for everything; hanging planters, raised beds, and fixed planters.

The sand is local sourced from a nearby sand, gravel, concrete facility.
The peat is local harvested from an adjoining parcel.
The compost is aged horse manure from a neighbor.

I try to go into winter with a dozen 5-gallon buckets full of unused mix. So in early spring, while there is still a thick blanket of snow and everything is encased in ice, I have soil mix in the house that we can use for sprouting.

[aquietpath]

I've always read that seed starter mix was sterilized, and seedlings would not be exposed to anything in the soil that could harm them. I've always invested in the starter mix, and have had good luck with my seedlings. It's expensive, though.

I had read somewhere you could sterilize your own garden soil by baking it in the oven, and using that instead. NEVER AGAIN! The smell was horrendous. Never knew dirt could smell so bad.

[TinaMcG]

I have started many many vegetables from seed in situ outdoors, without giving a thought to incubating them in a special medium. But then, they're outdoors in ideal conditions. I actually have much better success not starting seeds in special media and then hardening them off and transplanting outdoors later on. I did it for decades. Now I don't.l Seeds sown outside catch up real quick.

[uggabugga]

Originally Posted by aquietpath

I've always read that seed starter mix was sterilized, and seedlings would not be exposed to anything in the soil that could harm them. I've always invested in the starter mix, and have had good luck with my seedlings. It's expensive, though.

I had read somewhere you could sterilize your own garden soil by baking it in the oven, and using that instead. NEVER AGAIN! The smell was horrendous. Never knew dirt could smell so bad.

you raise a good point - one that made me finally go pay for a bag of seed starter mix.

i started a whole slew of seeds this spring in ordinary potting mix - a bag that had been opened last fall and sat in the garage.

i lost at least 80% of my seedlings from damping off . it seems like once the plants get a little bigger they can fight that off, but are very vulnerable early on.

and yeah, baked or autoclaved soil smells absolutely horrendous. a friend in the govt. outside DC told me a funny story once about michelle obama receiving a 'gift' of soil from some small town in ireland where one of her ancestors was allegedly originally from. to keep from introducing anything nasty into the country, it was required that the soil had to go to beltsville, MD and get autoclaved before she could take possession of it. i always had this picture in my head of her taking a big sniff of it - like you normally would, since rich soil smells good - and getting a very unpleasant surprise.

[Cambium]

I actually did a test a year after posting this thread.


You can find it here. Looks like you can successfully grow seeds in straight up potting soil but the Organic one did better than the regular one. However the Seed starting soil is the best way to go for germination

Seed Starting Soil Test

[BellaDL]

Here is my experience with seed starting in different types of growing mediums

1. Direct sowing: better germination rate and faster time when the soil is warm and 'loamy'. I planted peas, lettuce, mesclun, radishes, beets and beans on April 1 (when temps were in the 60s then it got cold again). Peas and radishes came up few weeks later. Lettuce /mesclun and beets emerged in mid May. Beans did not come up until late May then most of them got eaten by cutworms!

I usually started beets and beans indoor but decided to sow direct this year. I will start beans inside next year and put a protective tube around them when transplanting.

2. Potting soil indoor: very slow with poor germination rate. Unlike garden soil, the potting soil seems to get more compacted with watering. I think the dense texture makes it difficult for the seeds to germinate. I made the mistake of starting seeds in potting soil this year (the local garden center ran out of peat moss and had no seed starting soil). It was a bad experiment with only about 2% germination rate. I had to restart 2 weeks later when peat moss was available.

3. Seed starting soil: faster than direct sowing and better germination rate. I made my own seed starting soil (4 parts compost, 1 part perlite, 1 part vermiculite and 2 parts peat moss).

I found the best method is to germinate the seeds on wet paper towel in a closed plastic container (inside a heated lidded plastic bin - I put the containers on a tray with a 25 watt bulb under. This works much better than a heating mat).

Once the seeds have germinated, I transferred them to seedling trays. I discovered silicone seedling trays this year and absolutely love them (reusable and easy to transplant seedlings).

https://www.sili-seedlings.com/

With the exception of watermelon seeds, I have had 100% success with starting the seeds on wet paper towel then seed starting soil.

[uggabugga]

i use the wet paper towel in a baggie method too, unless dealing with really tiny seeds.