Raised Bed for the Balcony: Building, Filling and Planting

If you've ever wished you had more growing space on your balcony, a raised bed might be the answer you didn't know you were looking for. It gives you deeper soil than a typical pot, which means healthier roots, less frequent watering, and the ability to grow things that struggle in shallow containers. Plus, you get to garden standing up. Your back will thank you.

But a balcony isn't a backyard. You can't just stack some pallets and dump in a bag of soil. Weight limits, drainage, and sizing all need careful thought. Let's walk through everything step by step.

Before You Build: Weight and Space

This is the part most guides skip, and it's the most important. A filled raised bed is heavy. A bed measuring 100 x 40 x 30 cm holds roughly 120 litres of soil mix, which can weigh 80-100 kg when wet. Add the bed itself and you're easily over 100 kg in a single spot.

Measure your available space carefully. Leave at least 60 cm of walkway so you can move around comfortably. If your balcony is narrow, consider a long, slim bed (100 x 30 cm) rather than a wide one.

Choosing Your Material

You have several good options, each with trade-offs:

• Wood (larch or Douglas fir): Classic look, naturally rot-resistant. Line the inside with pond liner to extend its life. Avoid treated wood near edibles.
• Metal (Corten steel or galvanised): Sleek and modern. Corten develops a beautiful rust patina. Galvanised steel stays silver. Both are incredibly durable.
• Fabric grow bags: The lightest option by far. A 100-litre fabric bed weighs almost nothing empty. They fold flat for storage. Drainage is excellent because water seeps through the fabric. The downside is they dry out faster.
• Pre-made elevated planters: Many garden shops sell raised planters on legs. These are the easiest option if you don't want to build anything from scratch.

How to Fill a Raised Bed Properly

This is where many balcony gardeners go wrong. Don't just fill the entire bed with potting soil. It's expensive, heavy, and compacts over time. Use a layered approach instead:

1. Bottom layer (about 25%): Drainage material. Lightweight expanded clay aggregate (LECA) or perlite. This keeps the weight down and prevents waterlogging. On a balcony, this layer is crucial.
2. Middle layer (about 25%): Rough compost, partially decomposed leaves, or coconut coir. This holds moisture without adding excessive weight and breaks down slowly to feed your plants.
3. Top layer (about 50%): Quality potting mix blended with a handful of slow-release fertiliser. This is where your plant roots will do most of their work.

Don't forget drainage. If your bed doesn't have drainage holes, drill some before filling. Place a saucer or tray underneath to catch runoff and protect your balcony floor. For more on getting the soil mix right, our pots and soil guide has you covered.

What to Plant in a Balcony Raised Bed

The extra soil depth opens up options that regular pots can't offer. Here are some winning combinations:

If you're planting herbs, our basil care guide pairs perfectly with raised bed growing. And for tomatoes, our container tomatoes guide covers everything from variety selection to staking.

Maintenance Tips

• Watering: Raised beds dry out faster than ground-level beds but slower than small pots. Check soil moisture every day in summer. For a detailed schedule, see our watering frequency guide.
• Feeding: Top-dress with compost or slow-release granules at the start of each growing season. Liquid feed every two weeks during peak growth.
• Soil settling: Your bed will lose about 10-15% of its volume over a season as organic material decomposes. Top up with fresh compost in spring.
• Winter care: If your bed is wood, elevate it on pot feet to prevent moisture damage. Empty and store fabric beds over winter.

A raised bed transforms what's possible on a balcony. You go from a handful of pots to something that genuinely feels like a garden. Start with one bed this spring, see how it works for your space, and expand from there. Your balcony has more potential than you think.