Do you have a box store such as Home Depot, Lowes, K-mart, Wal-mart close by? Those stores normally carry what we refer to as "cactus mix". Any brand will do. Joshua Trees are not all that fussy about special soil requirements but do prefer to have good drainage. Or you could just use 2 parts regular potting mix with 1 part perlite added. Let the seedlings develop at least 5-7 leaves then gently use a mini hand towel or tweezers to push the seedling off and plant in a new container with fresh mix. Water well and do let soil dry out between watering.

Thanks for the information! I looked in a Lowes and found out that they did have the soil brand, but they were out of it. Also, our Wal mart does not carry it. Is there any other information on growing Joshua Trees that I should know? Please tell me if you have any other information since this is my first time growing them.

PS I had planted eight seeds in the beginning of the month. Out of those only three sprouted, but the third one died before it produced its first leaf. The other two so far are doing well.

Don't overwater and give them as much light as possible as they grow. You don't want to fry the seedlings but they are going to need a ton of light later on.

You can make your own cactus mix by adding perlite and sand to potting soil.

I have a Joshua Tree growing that I started in Feb.. It is now 6 in. high. I started it in cactus soil in a peat pot. Then I repotted it, peat pot and all in a larger pot with cactus soil. I took it to the shore with me for 3 weeks to care for it. 15 yrs. ago after returning from Joshua Tree Nat. pk, I had 2 growing that were a foot hugh. Planted them out in Pennsylvania soil and they did not survive the winter. This one will stay inside in the winter.