Raised garden beds soil

Question

Hello, I have built raised garden beds in my backyard. They are about 24 inches high (pretty tall). I need to fill the first 6 inches with something lightweight that won’t put a lot of pressure on the bottom of the beds over time. The boxes are built out of cedar fence pickets. The recommended fill depth for the soil I am getting is 18 inches max, after which the soil risks becoming anaerobic. I live in Austin, TX.

Question :1 – Should I line the inside of the garden box with anything to keep the dirt inside the boxes + keep moisture in? If so, what should I use?

Question 2: What should I fill the first 6 inches with? Leaves and twigs? Scrap wood? I have some fill dirt that I can use, but I’m worried that it will crack the garden beds over time.

Any other things I should be thinking about with a setup like mine?

Thanks in advance 🙂

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Answer 1

There are several ways to go about filling the beds with soil. The links below will help you.
Plastic would not be necessary when using cedar as it is naturally resistant to rot, but there would be no harm in doing so. Do not line the bottom.

http://www.gardeninginraisedbeds.com/raised-bed-soil-mix/the-perfect-soil-mixture-for-filling-your-raised-bed/
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/best-soil-raised-garden-beds.htm