GoodSeed Farm > Raised Bed Soil Recommendations

Raised Bed Soil Recommendations

A jungle of weeds can quickly take over your raised garden beds if you fill them with the wrong soil. (GoodSeed Nursery photo)


Let’s agree that raised-bed gardening is the key to growing lots of healthy plants with the least effort. Raised beds are containers of soil above ground level, with space to walk around them without packing the growing soil down and squeezing out all the air. They also prevent the surrounding grass and weeds from invading and competing with the garden plants. Gardening in raised beds is physically easier, and takes less space.

So, what’s the best soil to fill your raised beds with? That depends on what you’re planning to grow, but here are a few basic rules: First, raised bed soil should be very light and fluffy. Heavy soils expand when they freeze, which will tear your raised beds apart over time. Light, fluffy soils in raised beds drain quickly, so plants won’t drown. Plants breathe through their roots, so air is the secret ingredient of healthy garden soil.

Good planting soils have lots of organic matter like compost and peat moss. These ingredients keep the soil loose so it can breathe and drain, and roots can spread easily. Compost also contains hundreds of valuable trace minerals and live organisms like soil microbes and earthworms. These ingredients help plants digest their food, and prevent diseases caused by malnutrition. No amount of concentrated fertilizers like Miracle-Gro or 12-12-12 can replace the natural goodness of rich compost.

Different plants need different soils. Acid-loving plants like strawberries, blueberries, and raspberries like acid soils, so raised beds for growing them should be filled with pine bark and peat moss, mixed with well-composted manure and Holly-Tone fertilizer. Holly-Tone is an old-fashioned, meal-based ground fertilizer rich with trace minerals and soil microbes.

Vegetables do best in a rich mix of composted manure and well-composted sawdust, with perhaps some course sand added for texture. Each vegetable has its preferred plant food, but you can’t go wrong mixing in a good organic fertilizer like Espoma Garden-Tone when you first prepare the soil for planting. Fertilizers that are high in nitrogen are good for leafy crops, but fruits and root crops do better with less nitrogen but more potassium and phosphorus. The important thing is that mixing plant foods into the soil is better than spreading them on top.

Here’s where many raised bed gardeners go off-track. Mixing any kind of dirt, whether it be “topsoil” or clay, will make the soil in your raised beds eventually pack down into a brick. Commercial growers never use topsoil or dirt; they prefer “soil-less” growing mixes made from sterile ingredients like well-composted sawdust, peat moss, vermiculite, perlite and mushroom compost. These soils have the ideal texture for plant roots, won’t swell when frozen, and won’t pack down.

Smart gardeners avoid adding anything that might contain weed seeds. Weeding is the most tedious drudgery in gardening, so why plant weeds in your fancy raised beds? Soil-less mixes are sterile, either from high-heat composting or because, like peat moss and vermiculite, they come from deep underground. Mushroom compost is also sterile, unlike the free horse manure your neighbor so kindly gave you. Horses don’t digest weed seeds completely, so horse manure introduces pasture weeds into your garden unless it’s scientifically composted. Cow manure is better, since cows have thorough digestion.

Does all this mean you have to buy expensive container mixes for raised bed gardening? Not really. GoodSeed Nursery offers pre-mixed, weed-free raised bed soils in bulk, or all the ingredients to mix your own. If you’ve invested in raised beds, make sure you fill them with soil that will make your plants thrive. Good soils are the key to raised bed gardening, and in future years you can just add a few inches to the top at planting time.