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Hi!
I want to build a raised garden bed against our garage (where you can see the cardboard and pipes on the ground in the attached photo). Our backyard is uneven and has some lower spots, including directly beside the shed. It's an old shed on a concrete slab, but I can see there's a good couple of inches of rust at the bottom where water has started to pool. There's about a 110-150mm drop down to the slab.
My gut feeling is that I should probably correct the drainage before installing the raised garden bed - possibly by building up the soil next to the shed to make it more even or cutting into the rise on the left of the shed, but I'm not entirely sure! Can I please get some advice on how to get started? We are also planning to install a gravel pathway straight down from the garden shed beside the garage and raised garden bed, but it would be good to at least get the foundation beside the garage right now so I can build the garden bed and get our spring veggies growing.
Welcome to the Bunnings Workshop community @PB1. It's sensational to have you join us, and many thanks for your question about building a raised garden bed.
It's great that you're planning to build a raised garden bed and pathway in your backyard. Before you start, it's definitely important to address the drainage issue next to your shed, especially given the rust you've noticed. Building up soil directly against the shed isn't the best idea because it could exacerbate moisture problems and further damage the shed's base. Instead, I'd suggest considering levelling the area by removing some soil to create a more even surface for your raised garden bed.
Since your backyard has some uneven spots, you have a couple of options to consider for levelling the area. One approach is to remove enough soil to create a level foundation for the garden bed without bringing the soil up against the shed. This would prevent any potential water pooling and rust issues from getting worse.
For the pathway, it's also important to create a level surface to ensure proper drainage and avoid any trip hazards. Given the drop in elevation, you might want to decide where to place the retaining wall to manage the different heights effectively. You could level the entire area, including where the garden bed and pathway will go. This would mean excavating the area next to the shed and creating a small retaining wall between the newly levelled area and the higher lawn. This method would keep the garden bed, shed, and pathway all on the same level, providing a uniform appearance and possibly simplifying construction. Alternatively, you could keep the pathway at the same height as the lawn. In this case, you'd need to build a retaining wall between the path and the newly levelled area for the garden bed. This approach could be more visually appealing if you want to maintain a sense of separation between the garden bed and the pathway, and it would keep the lawn and path on the same level for easier access.
Both options would help with drainage by ensuring water flows away from the shed and doesn't pool around it. Whichever approach you choose, make sure to include a slight slope in your design to guide water away from structures and prevent future issues. Also, consider installing some drainage solutions, like a French drain or gravel-filled trench, along the shed to further protect it from moisture.
Here's a helpful guide: How to build a raised garden bed. Also, for inspiration, check out our Top 10 most popular raised garden beds.
Please let me know if you have any questions.
Mitchell
