How to Build Raised Garden Beds: 7 Steps That Actually Work

Step 7: Fill and Prepare for Planting

Let me tell you about the most crucial part of building raised beds – getting the soil mix just right! After building dozens of raised beds over the years, I’ve learned (sometimes the hard way) that your garden’s success depends heavily on what goes inside those beautiful wooden frames.

The Perfect Soil Recipe

I’ll never forget my first raised bed disaster. I thought I could just fill it with regular garden soil, and boy, was I wrong! After a season of poor growth and waterlogged plants, I finally discovered the magic ratio: 40-40-20. That’s 40% topsoil, 40% compost, and 20% aeration materials like perlite or vermiculite.

This mixture has been my go-to formula for years, and here’s why it works so well. The topsoil provides essential nutrients and minerals, while the compost adds organic matter and beneficial microorganisms. The aeration materials prevent soil compaction – something I learned was absolutely crucial after my first failed attempt!

Layering Like a Pro

Think of building your soil layers like making a lasagna (yes, really!). Start with a layer of cardboard at the bottom – this helps suppress weeds and attracts earthworms. Then, alternate your soil mixture in 6-inch layers, gently tamping down each layer as you go.

Here’s a pro tip I discovered after years of trial and error: mix your ingredients on a large tarp before filling the bed. It’s so much easier than trying to mix them in the bed itself! Trust me, your back will thank you later.

Calculate Once, Fill Once

Nothing’s worse than running out of soil halfway through! Here’s the formula I use: Length x Width x Height = Cubic Feet needed. Then add about 10% extra for settling. For example, a 4x8x2 foot bed needs roughly 64 cubic feet of soil mixture. Always better to have a little extra than not enough!

Essential Amendments

Over the years, I’ve found that adding these key amendments makes a huge difference:

Bone meal for phosphorus
Blood meal for nitrogen
Azomite for minerals
A cup of epsom salt per 4×8 bed for magnesium

First Watering Session

Here’s something most guides don’t tell you – your first watering is super important! I water in layers as I fill the bed, using a gentle shower setting on my hose nozzle. The goal is to get it thoroughly moist but not waterlogged. You’ll know it’s right when you squeeze a handful of soil and it holds together without dripping.

Want to know how to maintain your raised bed for years to come? Click the “next” button below to discover my tried-and-true maintenance secrets, including how I’ve kept some of my beds producing abundantly for over a decade! I’ll share my seasonal care checklist and the biggest mistakes to avoid.