If you want to know what is in your mix the only way I can suggest is to mix your own. Standard mix would be peat moss and perlite sometime with vermiculite. The ratio can vary from 5 part peat to 1 part perlite to just the opposite for 5 part perlite to 1 part peat moss. The big range is dependant on what all you are germinating. Most veggies should do fine at 70 percent peat moss 30 percent perlite. Neither product will have any additive to it. You supply any needed nutrient based on need and plant preferences. Coconut coir is gaining in popularity as a seed starting mix also but may be expensive or hard to find unless you are near Helena or Billings. Here in Texas over the last year or two I haven't found any potting mix (pre-mixed) that did not have added (nutrients) aka slow release n-p-k, aka osmocote or some variation of it. One more thought is to the sizes of containers you are starting seed and type of seed. Some use flats and prick plants out as they pop up, others use anywhere from 512 cell flats all the way to 4 inch pots. The smaller the cell size the finer the grade of peat and perlite you use. The ratio of peat to perlite would also be highest 5 to 1 peat to perlite for smallest container. The biggest pots and or slowest germinating seed would be just the opposite at 5 to 1 perlite to peat. I am trying to give you the dynamics involved and not specifics because I am not sure what all you plan to grow. I hope this helps you in your venture Good Luck and Happy Growing David

I use Miracle Grow potting mix and always have great results. As of right now, I have coleus, lupines, black pansies, and blue poppies all growing in it under my lights, with very good germination rates. I've used potting soil of various brands, even Miracle Grow Garden Soil, which the instructions clearly state not to use in containers. It seems to me that unless you have a really finicky plant, they are happy with almost anything. Many plants reseed without our help, and sometimes in odd places. Nature has given the seeds what they need to do their thing. The best we can do is try to imitate it. If you're still not sure, I would recommend trying first with seeds that are easy to replace. (this is what I did when I decided to take the leap into winter sowing.) That way, it won't be absolutely heartbreaking if something goes wrong. Good luck!

I used the Jiffy mix (bought at WalMart) to start my seeds in. I purchased some VERY small tomato seedlings in Jan (We're talking 3" at the very most), when I knew absolutely nothing about what I was doing, and put them in the MG organic potting mix in containers outside, and kept them outside in some pretty chilly temps. (You may have seen some of my previous posts on this.) To my surprise, they are doing well. (They had a few unhappy days, but have since perked back up.) I bring them inside when the temps fall below 40 at night, but otherwise, they stay out and are growing. (We'll see how they produce in comparison to my other plants) I realize this doesn't answer your question about starting your seeds in the MG Organic mix, but it does at least give you some perspective as to how well some very small seedlings worked in that medium. : )

DWD2, thank you for posting your methodology. It always good to see how others grow their seeds and compare methods. I have grown my own starts (36+ tomato varieties) for the past 5 years. Before last year, I had not had too many plant health problems, except for the first year when my light system was not close enough to my plants. In that year I had problems with leggyness. I strongly suspect that my problem last year was the seed starter mix, but it could have been a few other things. I may have introduced disease into the first batch by incorporating compost into the mix. I think this is unlikely because in other batches and other treys I did not use compost in the mix but still had the same problems. Also, once the plants were in the ground they recovered and grew well the rest of the summer. If it were a disease I would have expected that the plants would still have had problems after planting, which they did not. Tomatoes are really amazing in what they can take early on and still produce well. For example, I had a mouse eat all the leaves of two plants shortley after they were in the ground. There were only stems left and I thought they were done, but I did not pull them out. Both plants sprouted new leaves again and became bushy healthy plants. I was astounded. I have had others suggest that with an approximately 50/50 mix of vermiculite and peat, I may have had water retention problems that suffocated the roots. Thats possible, but I was pretty careful about my watering. I can't totally rule that out. It may also have been too many nutrients from a dilute solution of fertilizer at watering as the problems occured shortly after that. I have read that new seedlings don't need many nutrients becuase they get what they need from the seeds/cotyledons. Some have even suggested that you will cause more problems by fertilizing than just not fertilizing. The reason why I fertilized is because we had a number of storms in May that pushed my planting date back 3-4 weeks longer than our average frost date. So I fertilized a little. I may also have had root binding problems. There is another possiblity which DWD2 suggested. I used a seed heating matt for the first time last year and most of the tomatoes had it under them for at least a day. So I may have over-heated the soil a little and damaged the roots. However on the last seed trey that got started late, I did not use the heat matt because I suspected it may have caused the problems. Yet I still had the same problems in the last trey. My strongest suspicion is still the starter mix. I have read the ingredient list on several seed starting mixes. In most cases, they usually contain peat (as the main medium plus it has high cation exchange capacity) + vermiculite (for micro nutrient exchange and water retention) + lime (to balance the PH of the peat). They sometimes include perilite, but sometimes not (example Jiffy), they also sometimes include a few other things (mycorrhizae for example or a source of nutrients). The main ingredient that I was missing that most starter mixes have is lime for ph balance. I could not find lime in any stores in Utah at the time. They do sell it here, but it is not a common soil amendment in Utah because most Utah soils are slightly alkaline (PH 7.8-8.2). So most folks would not want to add lime. This year I am interested to try mixing my own starter again but I wanted actual recipies to get an idea of the right proportions to use. Also I had no idea that mycorrhizae was available so I am defintley going to use that in my mix. Alternatively I could just buy a pre-made starter mix, but I wanted to save money and its a learning experience as well.