How to fill gap between concrete apron and fence?

prodip

Hi everyone,

I'm completely new to DIY gardening and would love some advice.

We've recently built a new house and had a concrete apron installed around it. There's a 20–30 cm gap between the side fence and the concrete apron (around 20 cm near the fence posts). The concreting contractor recommended filling the entire gap with crushed rock to help prevent soil erosion over time and to protect the concrete. There's also a difference in height between our property and the neighbour's, so the depth of the gap varies.

Here are the measurements:

• Width: 20–30 cm
• Depth: Around 14 cm near the concrete, increasing to about 30 cm near the fence
• Length: Approximately 20 metres

Rather than filling the whole area with crushed rock, I was wondering if I could turn it into a narrow garden bed with small flowering plants.

My idea was to:

• Fill the lower section with crushed rock to create a stable base.
• Add garden soil on top.
• Install a weed mat, cutting holes where the plants will go.
• Finish with mulch or decorative pebbles to keep maintenance to a minimum.

I have also added a image generated by AI to help explain what I'm trying to do.

Is a garden bed in a space this narrow practical, or am I likely to run into problems?

I'd really appreciate any advice or suggestions. Thanks!

MitchellMc

Welcome to the Bunnings Workshop community @prodip. It's wonderful to have you join us and many thanks for your question about filling the narrow gap beside your concrete apron.

A narrow garden bed could work, but I’d be cautious about filling the whole space with soil. Soil held against the fence or concrete edge can trap moisture, and in a new home you’ll also want to avoid covering any termite inspection zones, drainage paths or weep holes. For that reason, I’d keep the lower section as free-draining crushed rock or drainage gravel, then only add planting pockets or shallow raised sections where you need them.

In a 20-30cm strip, your best options would be shallow-rooted, compact plants rather than anything that will become woody or push against the fence. If the area is shaded and narrow, you may find small pots or trough planters sitting on decorative gravel easier to control than a continuous soil bed. That would still soften the area visually while keeping drainage and maintenance much simpler.

I’d suggest laying geotextile fabric between the soil and drainage rock rather than relying only on weed mat over the top. This helps stop soil washing down into the rock. Then finish with mulch or decorative pebbles, keeping the surface level below the concrete apron so water does not run back toward the house.

Once thing that is a positive is that it looks like your garden bed will only come up as high as the sleepers under the fence.

These discussions should also help with ideas: How to landscape a narrow side towards the fence? by @Abhi352 and Recommendations for gap along fence by @CookedBread. You might also like this guide: How to build a garden bed.

Please let me know if you have further questions.

Mitchell