Potting Soil -VS- Seed Starting Mix

[Knucklehead]

I was curious about the differences between the Potting Soils and the Seed Starting Mixes. There is quite a bit of difference in the ingredients, the constitution of the ingredients, and even the fertilizer ratios. If you have had problems starting seeds in Potting Soil, regardless of the Manufacturer, these differences may help pinpoint the problem.

The Seed Starting Mixes are formulated for exactly what we are doing with them -- starting seed. They take up just enough water to keep the soil column moist but not wet. They are formulated with the knowledge that seedlings take up considerably less water than a larger thriving plant. They are light and easy for baby roots to pass through with no wood chunks to inhibit root growth downward. The mix is formulated for use in the most popular seed starting method - The 1020 trays. The Seed Starting Mix that I use is 85-95% Spagnum Peat Moss with the balance being Perlite. That's it. Fertilizer is 0.03-0.03-0.03. BigBonner uses a seed starting mixture formulated especially for tobacco. I received some of his mix when I bought some float trays from him. It looks just like the Seed Starting Mixture that I use, but the fertilizer was probably different. This year I began supplemental feeding a week after germination with great results, so I'm sure they keep the amount of fertilizer in the soil low on purpose to keep from burning fresh sprouts.
Miracle Gro Seed Starting Mix: http://www.miraclegro.com/smg/goprod/miracle-gro-seed-starter-potting-soil/prod70340
Seed Starting Mix label PDF showing ingredients and fertilizer: http://www.miraclegro.com/smg/products/CFLS/miraclegro_seedstarting_pottingmix_CFL.pdf

Potting Soil is formulated to transplant bare root plants into larger pots. The roots should be well established. It is formulated with 60-70% processed forest products (wood chunks, wood fibers, etc.), spagnum peat moss, perlite. Fertilizer is 0.21-0.11-0.16. It designed to maximum water retention for the larger plants that take up a lot more water than seedlings. The wood products hold and retain more water than peat moss. On purpose. For emerging seedlings the water retention of the wood products can cause mold, because more water is being drawn up by the wood products than can be taken in by the roots of seedlings. Wood products may even be more susceptible to mold than peat moss, but this is just my own theory. It could just be the extra water. Drowning and damping off are possible. Spiral root can be caused by the wood chunks interfering with the downward growth of the root shoot.
Miracle Gro Potting Soil: http://www.miraclegro.com/smg/goprod/miracle-gro-potting-soil/prod70332
Potting Soil label PDF showing ingredients and fertilizer: http://www.miraclegro.com/smg/products/Miracle-Gro/pdf/miraclegro_pottingmix_CFL.pdf

 

[Knucklehead]

Baccto Brand
Seedling Propagation Mix: http://baccto.com/commercial-grower/seedling-propagation-mix/
Potting Soil: http://baccto.com/home-gardening/premium-potting-soil/ (Not sure what "other ingredients" is, may be woody stuff)(Lists seed starting in applications)
Professional Planting Mix: http://baccto.com/home-gardening/professional-planting-mix/ (Lists seed starting in applications)

 

[ArizonaDave]

Extremely interesting, thanks for sharing! I guess I accidentally found a way around "potting soil". After initial sprout, I was waiting a while (few days) for the soil to dry out a bit, then mix in a little fertilizer and water, then add. This was after slow seedling starts last year. I will definitely purchase the proper product next grow.

 

[Knucklehead]

If somebody has some different brands of Potting Soil or Seed Starting Mix, please post the ingredients here. It may help narrow down future problems with different mixes.

 

[bonehead]

i use jiffy starting mix. i transplant into miraclegrow potting soil. i have to see if i have the empty bags around still.

 

[Brown Thumb]

The Baccto potting soil has very little Wood Chunks in it. It has become my favorite after using it this yr.
In second place for me is.
Black Gold Potting Soil, no chunks of wood but the plants took off a little slower than the Baccto.
The price for it is a lot more compared to the Baccto also.
QI hope your monitor rotates. Dang phones.

 

[ProfessorPangloss]

I use, and have always had amazing success with ProMix. It has the mycorrhizae inoculated and it performs outstandingly well in all kinds of nursery applications. At the commercial nursery I worked last summer, we used it for everything potted, and it never failed. I've used it as a seed starting mix, and if you want to "make" potting soil out of it, cut it 1:1 with composted cow manure.

I would add that peat moss holds more water than pretty much anything else, but that light consistency in any soil-less mix will get you an entire pot full of fibrous roots in no time, but you can always go to a bigger pot. Also, I see Baccto and Miracle Gro mentioned here. I've thought Miracle Gro to be inconsistent with their quality, and you have to beware which blend you buy. Some "moisture control" mixes contain a gelatinous substance like what's found in disposable diapers. It's sold by itself as "Soil Moist," and it's not all that useful. Maybe I'm a cranky hourly stooge, but I've always checked the water level of pots by lifting them up. Stay away from gimmicky moisture traps like the diaper goo.

I never buy a seed starting mix with composted bark. It's always dirt cheap, but it doesn't work as consistently as peat moss. It's basically filler. The cheap brands of "soil" at dollar stores -they look like dirt- are usually a LOT of bark, and I've never had any success trying to cheap it out.

A 3.7 foot bale of ProMix costs about $36 at the Co-Op here, but it goes a long way, and it's a small price to pay for nearly guaranteed success. If you're making stuff on a huge scale (and I mean like farmer huge), you could make your own from perlite, vermiculite, and peat moss. You'd need to get a mycorrhizae starter and you'd have to mix it all, and you'd have to add all the fertilizer yourself, but that could conceivably save a few bucks. I just keep buying ProMix.

http://www.promixfindgrowtopia.com/product/detail/pro-mix-ultimate-all-purpose-mix

just my $.02

 

[DGBAMA]

This is the one I use. They do not list a specific composition though.
http://baccto.com/home-gardening/peat/

 

[chris m]

I have always used pro mix growing soil it's a 2cu ft bale that when water is mixed with it it's 4cu ft . And mix in with 4 bales with ten pounds of coffee grounds . It's not good for seeding with the grounds .and it's 14.00 a bale will need 4 more for this year

 

[BarG]

They called it little baccto when I used it a couple years ago. I used the miracle grow seed starting mix this year which was very fine with no chuncks and no chlorides. Heres the specs..

Total nitrogen.......................0.03%
..... .015% amoniacal
..... .015% nitrate

Available phosphate P2o5.....0.03%
Soluble potash K2o............0.03%

derived from ammonium nitrate, ammonium phosphate, calcium phosphate and potassium sulphate.

It is supposed to be good for at least 6 weeks. After my seeds start good they are usually pretty wet for a while, when I let the soil dry out good without harming young seedlings I add a little epson with a mild dose of liguid fertilizer when water is needed. My plants are doing good this year. I have been paying attention.

I got the powder concentrate fertilizer from a trade with BigBonner. You could probably use miracle grow.

 

[Chicken]

This year i learned my lesson on using potting soil...instead of a seed starting mix....

Seed starting mix for me..from now on.

 

[Smokin Harley]

Im using Jiffy mix.