How can I amend Garden Soil to use in planter boxes?

Question

 

I live on an island and had garden soil delivered but now it says to mix 50/

50 with my soil – but we have very little soil here as it is all rocks. we are putting large planters around the south side of our deck instead of railings. We ordered Zgarden Soil – Scott’s from Home Depot and it was delivered by barge. However, now I see where it says to mix 50/50 with our soil. The problem is we have very little soil on this island and what we have is choked out with salah or cedar roots. I cannot return the soil. What can I do? I have perlite I can mix in – would that help?

Answer 1

You can sure use the soil mix you purchased. Adding some sand to the mix would be acceptable. Make sure it's clean.
Do you have any compost available to you? This would also be a great addition to the mix.
Some perlite could also be used.
Your looking for a light, loamy feel to the mixture. It needs to retain moisture but drain.
Mix in a large tub or even on a large tarp laid out on the ground.

Here are a few links to help you.

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/using-topsoil-and-potting-soil.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soilless-growing-mediums.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/perlite-potting-soil.htm