I've put potting mix, garden soil & decomposed cow manure in pots (and 15 gallon grow bags). Worked for brugs and flowers. However this year everything is going in straight potting mix. Better drainage, roots grow faster and it isn't as heavy (those grow-bags weigh 40 lbs).

Agree - mixing in garden soil (dirt) just increases your risks and problems 10 fold. Especially for those new to the process.

Stick with soil-less container potting mix. There are numerous good brands available - just read the ingredients to make sure there is no soil in it.

Dave

I am currently using a seed starting mix, once they have grown can I continue using the mix or should I transfer them to actual potting soil?

Seed starting mixes usually have no nutrients in them. So once germinated most of us transplant to a good "growing mix" a soil-less mix that has some time release fertilizer added to it and is more coarse in structure. The more coarse structure allows for better root development and better drainage to prevent root rot.

But it is NOT recommended that you ever use "soil" or dirt of any kind in containers because it compacts in the container, suffocates roots and drains so poorly. Use potting MIX not potting SOIL.

Dave

Can I start the seeds in the potting mix to begin with, and save myself the transplanting step?

Well I suppose you could try. ;) The reason seed starting mixes don't have any fertilizer in them is because new germinated seedlings can't handle them - it burns the plant. Only after the seedling develops it first set of true leaves can it benefit from fertilizers.

As to the need for transplanting - there are several detained discussions here about this - but in a nutshell, at least one transplanting is required to trigger fibrous root development - the kind the plant needs to survive and produce. Without that trigger of transplanting the seedling only develops tap roots. It's a hormone thing like "puberty". So, as we always say, do what is best for the plant, not what is most convenient for the gardener. ;)

Dave

Thanks for your help Dave, it was very informative. I wanted to ask if you know anything about moon flowers? I have some growing in a hanging basket,can they stay in the basket or will I need to transfer them to a box with a trellis of some kind? Also the weather here went from 90 degrees to 57 degrees and very overcast with no sun,what can I do to get them more sunlight?
Toni