For starting transplants: I use ProMix for the first time this year and was quite happy with the results. Also use Jiffy Mix and some of my own 1/2 & 1/2 peat and compost mix.

Over on the Growing from Seed Forum you'll find several recipes for making your own mixes and lots of good tips in the FAQ there. Be sure to read the one on Damp-Off. And in the Container Gardening Forum you will find lots of good info for growing plants in containers.

For growing on transplants in containers I use the WalMart brand of potting mix, or ProMix, or my 1/2 & 1/2 compost and peat mix depending on the size of the container and the variety of plant.

Transplant size can be a factor as can transplant shock, proper hardening off transplants, and properly draining soil. Lots of potential causes.

But I have to say that regardless of the mix you use, with a 50% loss you are very likely over-watering and moisture meters are often very unreliable. I say that because most will agree that far more plants are killed by excessive watering than by anything else. Just something to consider.;)

Dave

Seedlings can be transplanted into a good, porous potting medium. In my opinion, the more porous....the better! Mine is a mixture of a high quality potting medium ( I use a Fafard professional mix, but have used Pro Mix) and perlite, mixed about 50:50.

Utilization of a fast draining medium makes it pretty darned difficult to over water! It provides the new root system with plenty of air spaces...a feature that is absolutely essential for rapid development.

Potting soil is for houseplants--always use something like ProMix, Fafard's #2, Sunshine Mix, Metro Mix 360, etc, that is considered "soilless." They are all peat-based, most with different percentages amongst many formulations, and most have calcitic and/or dolomitic lime to adjust pH, as well as various percentages of perlite & vermiculite... some with other ingredients as well, like bark. It's often a regional thing too, ProMix & (Fafard's too I believe,) is made in Canada, may not be available everywhere... I use ProMix BX or Fafard's #2. I think Craig, in NC, uses Metro Mix 300 or 360. Rhizo's tip on mixing with perlite is good too, especially if perlite is cheaper.

Mark, don't really think potting 'soil' is for houseplants either. That would kill everyone's houseplants sooner or later. Just such lousey drainage. Even houseplants would do better with a soilless mix.

I don't know what the labels say but I would only use that stuff in the garden itself never in containers.

Mix up the bleach at 10% and soak flats and domes first, or use Physan 20 at 2 T per gallon.
I'd never use anything again but the promix seed starter mix with biofungicide, and then transplant into promix hp.
You won't lose a one.
If you're not familiar with Promix, you can probably get it at a good local garden center.Be prepared to pay around $20 for a bag retail though. It's worth it!

Lots of good advice, THANKS. I've finally mastered making newspaper pots according to Eric. I've see pix of folks using them exclusively and wonder if they are "cleaner" than plastic pots from other store-bought plants. I will get Promix if I can find it. Any thing is worth trying. Its very disheartening to watch seemingly healthy 4&5" baby tomato plants just wilt and die. I usually water them when they are dry to the touch and the moisture meter is about 1/2 way up the scale.
At times like this, I sometimes wish a year were about 3 months long so I could try some of the advice:-) (Be careful what you wish for, huh??)
Thanks again. I knew I could count on you experts. I didn't realize, before I signed onto this forum, how avid some of you folks are about tomatoes and growing them. Most of you have forgotten more than I'll ever know.

Curly

Curly - if you can't find it locally the company has a store finder on their site (linked below). And you can also oder it on line. Home Harvest carries it as do several of the online gardening stores. I think you'll like it. Good luck! ;)

Dave

PS: Nothing wrong with Metro Mix 360 either if you can find it. Used to be able to get it here locally but the nursery closed so it is hard to find down here now.

Here is a link that might be useful: Pro-Mix