Lambrakis continues, “To use cardboard, be sure to avoid pieces with glossy surfaces or heavily printed ones, then lay it “over the entire bottom with overlapping layers to prevent gaps, moisten the cardboard to help it break down faster, and immediately pour on your soil mix to hold everything in place.”
Step 6: Fill with soil
Now for the good stuff—filling the bed. Use a mix of:
- Topsoil for structure
- Compost for nutrients
- Organic matter like fallen leaves, twigs, or aged manure for moisture retention and aeration
A good ratio is 60% topsoil, 30% compost, and 10% organic matter. “For filling a raised garden bed before planting, you should have two to three layers,” Lambrakis says. “The first is an optional base layer of logs, sticks, or coarse organic matter to improve drainage and reduce soil usage in deep beds. The second is a mix of compost, leaves, or aged manure to add nutrients. The top layer is high-quality garden soil mixed with compost (about 50/50) to provide a rich growing medium.”
Mix thoroughly and water well to help it settle before planting. If you’re filling a tall bed, save money by adding a base layer of logs, sticks, or coarse mulch underneath your soil mix—sort of like Hügelkultur gardening, an ancient German method of gardening on mounds like you’re in a Lord of the Rings movie. It’ll break down over time and improve the soil structure.
Step 7: Plant and maintain
Once your bed is filled, break out your most glamorous gardening gloves and hat: You’re ready to plant. Cocktail herbs, leafy greens, tomatoes, peppers, strawberries, flowers—you name it, they often thrive in a raised bed.
Add a two- to three-inch layer of mulch on top to retain moisture and keep weeds down. And consider setting up a self-watering system or soaker hose to make watering easier throughout the growing season. Raised beds do tend to dry out faster than in-ground beds, so keep an eye on soil moisture—especially during summer’s inevitable hot spells.
Want to make your edible garden bed planter a maximalist fantasy, à la Bunny Mellon? Add a trellis for climbing plants like cucumbers, pretty pavers around the exterior, and cloche covers to keep pests at bay (this cover from IKEA is beloved for its sturdy powder-coated steel frame). The prettier it is, the more you’ll want to be out there with your hands in the dirt.
What type of wood is best for raised garden beds?
Cedar and redwood are top choices because they’re naturally rot- and insect-resistant—handy accolades for an outdoor raised garden bed that can help yours last up to 10 years. If you’re on a budget, untreated pine works too, but it may not last as long. Avoid pressure-treated lumber for crop gardens unless it’s labeled safe for food use. Not up for a DIY garden bed? Fret not. There are ready-made options aplenty. One go-to of AD editors: the Asparen planter from IKEA.
How deep should a raised bed be?
A minimum depth of 12 inches is good for most herbs and shallow-rooted vegetables. For root crops like carrots or potatoes, aim for 18 to 24 inches. The deeper the bed, the more room roots have to grow—and the better your drainage.
Can I put a raised bed on concrete or a patio?
Absolutely. Just make sure there’s drainage—drill holes in the bottom if your bed has a solid base, or leave the bottom open and raise it slightly off the ground. You’ll need deeper soil (18+ inches) since roots can’t grow below the bed.
How often should I water my raised garden bed?
Raised beds drain faster than in-ground beds, so they need more frequent watering—especially in sweltering or windy weather. Check soil moisture daily during peak season with a simple finger poke. (The laziest among us—moi, in my own garden—may want to install a drip irrigation system or some such).