That will depend on which of the many products this manufacturer makes. Nothing I can find on the web site indicates what the pH of the various pottng soil mixes would be but since they have potting soil for specifically for plants the prefer a more acidic soil as well as general purpose soils, one may be balanced toward just slightly (like in the 6.2 to 6.8) range.

Do you know what a good acidic soil would be?

The Conifers forum here could best advise you I think as many there focus on redwood propagation. Otherwise just Google "how to propagate redwood trees". I did and many discussions and info links came up.

A heavily peat based potting soil should be acidic enough for them but not pure peat. This recipe is recommended for growing conifers but I have no personal experience with it.

ACIDIC POTTING SOIL
This mix is excellent for Azaleas, Camellias, Rhododendron, Hydrangeas, and Evergreens.

2 parts potting mix
1 part coarse sand or perlite
1 part peat moss
½ part well composted manure

Dave

Here is a link that might be useful: Conifers Forum

If you're buying potting soil and you want acidic potting soil, you can probably find soil for azaleas, rhododendrons, etc, or maybe it will just say "for acid loving plants" or something along those lines.

There are also fertilizers for acid loving plants. They'll either say they're for acid loving plants or they may say something like azalea or rhododendron. One brand name I can think of is Mr-A-Cid.

So instead of perlite, can I use vermiculite?

Different goals for the two but probably. Perlite is used to increase the air in the soil - it changes the soil density and provides no moisture retention but in fact improves drainage. Vermiculite retains water and improves the soil density somewhat but not as well as perlite. You'll have to monitor soil drainage more with the vermiculite. As proper soil drainage is very important with young seedlings, the perlite would be better if you can get it I think.

Dave