What kind of soil should I use?

[SNBerry]

So I am new to gardening and I would like to make sure all of my plants have the correct soil. I have had a few plants die recently and I realized that the soil may be the issue.

I purchased a seed starting soil from miracle grow for all of my plants. I figured that I could use the soil for the plants that were not starting from seeds as well. Now I am starting to think otherwise as of today. I think the plant's roots had been rotting.

Now, I have one plant that may be a Dieffenbachia. This is the plant that I pulled out of the soil today and decided the roots were rotting.

I have the following plants:
Aloe
Parlor Palm
Purple Velvet plant (three to a pot)
Pepperomia (Mini Watermelon)
Dracaena Janet Craig Compacta
What I think is a Chinese evergreen

I have the two Pepperomias and the Dracaena in the same pot

After looking through different websites it seems like they all need well-drained soil. I am thinking that I may be able to get the cactus, palm, and citrus mix for all of the plants above since the website say to use peat moss, sand and soil for the majority of the plants.

Is this possible or should I purchase a different mixes?

[rainbowgardener]

The cactus/ citrus mix should work for most of them.

Seed starting mix is ONLY for starting seeds. It has no nutrients or fertilizer in it, so unless you fertilize heavily, everything will die in it. If you don't want to use the cactus mix (might be excessively lean and well draining for the purple velvet, pepperonia, and maybe the chinese evergreen), then look for just regular potting soil with nutrients... Miracle Gro makes some or there are organic versions from better companies.

And don't over water. The stuff in cactus mix will need watering more often, because it is so free draining. The stuff in potting soil should have a chance to dry out between waterings. Root rot is almost always related to excess moisture and not having a chance to dry out.