Raised beds are essentially extra-large planters, generally made of wood, brick, or stone.
It may be tough to disassociate gardens with raised garden beds, as this is such a common element in today’s home gardens. But, take a minute to consider whether you really need raised beds. They can be costly to build and are resources intensive, which has impacts on the planet. For many, planting directly in the ground is the easiest and cheapest option.
However, they’re a great option if you’re unsure of the health of your existing soil (as is the case in many urban areas). Because the beds are raised up from the ground, they also help prevent back strain, since you won’t have to bend down far to tend your plants. Their height may discourage some garden pests, and they have excellent drainage by design, making it tough to overwater them (but also tough to keep moist if you live in a dry area).
Although you can purchase ready-made raised beds, making your own can save money—and help ensure that all of the materials are as good for the planet as your garden. There are a number of things to consider when building raised beds such as depth, width, and materials.
Length and width are important elements of designing any garden bed (raised or not), which are covered here.
Depth is a new variable if you’re planting in raised beds. No matter what you’re growing, beds should be an absolute minimum of six to twelve inches deep. This minimum is most appropriate for plants with small root systems like lettuce and other greens. If you want to grow root vegetables, like carrots or beets, consider the final size of these vegetables and ensure your bed is at least this deep, plus a few inches extra. For larger plants—like tomatoes—and more substantially rooted perennial plants, consider providing the same amount of root space as the plant takes up above ground.
Avoid pressure treated woods. There are a number of chemicals and fungicides used in pressure treated wood—these types of wood are actually prohibited under the organic certification, which means you probably don’t want to use it for the food you are growing at home either!
Some woods are naturally rot-resistant, which make them the most natural option for building a garden bed frame. Cedar, black locust, and redwood are examples of this, with lifespans up to 15 years once exposed to the elements in your garden. Do your research on the wood’s source and choose sustainable options when possible.
There are many recipes for creating natural wood sealants using beeswax, jojoba oil, linseed oil, and others. Here are some examples. You might also consider other long-lasting materials, like pavers.
You’ll also need to fill the beds with soil. Contact your local garden stores and even local farm and compost operations to find the option that fits your budget and your goals of being part of the climate solution. Soil is often the most expensive material in creating raised beds. Choose organic and local options where possible. If you can’t find local soils, consider mixing whatever option you do have with locally made compost, in a ratio of 1:1. The local compost has rich microorganisms adapted to your area that will thrive to support healthy crop growth and carbon capture in your soil.
Potting soil can also work well for elevated raised beds.
Building garden beds
Every garden bed will be uniquely suited to each gardener’s needs. Those with back issues, will want taller beds. Those worried about gophers will fasten chicken wire to the bottom before adding soil. Some beds will be built right on top of existing soil to extend the root area and welcome native soil microbes into the bed, while others will place beds on impermeable surfaces or need to create barriers to ensure roots don’t come in contact with toxic soils underneath. Still others will incorporate crop covers or insulation for pests and challenging climates. YouTube is full of amazing tutorials for all needs.