Few things send blood coursing through a green thumb faster than a new garden project. For me, it was the flower garden experiment last summer, which started with the Raised Bed Project the previous fall. Both had happy outcomes, but the cutting garden wouldn’t have been nearly as satisfying without the simple, wood-framed raised beds I planted it in.
How deep should a raised flower bed be?
Once you build your raised bed, you can fill it with soil and compost. If the plants you are growing require drier soil or if drainage is a problem, the garden bed could be taller and filled with a soilless growing mix. Flower and vegetable beds should be between 12 and 18 inches deep.
Use a durable, stable, and attractive material for the edge of your raised bed. The edging gives the raised bed its “curb appeal” within your garden. It not only holds the soil in place, but the frame also establishes the outline of the bed. You could use simple materials such as landscape timbers, railroad ties, or metal strips as edgings. But, if you prefer a more intricate design, you can use stone or mortared brick. A crested bed may or may not have a frame. In this type of raised bed, the soil is simply mounded from the bed’s edges to the center.
What kind of wood should I use for raised beds?
Wood is a popular choice for building raised beds and plant boxes because it’s relatively inexpensive. It also lasts for several years and readily available. Choose the wood you use carefully to avoid contaminating the soil. Make sure that your choice of wood is affordable, long-lasting, and eco-friendly.
If you live in termite territory, wood might not be the best material for your raised garden bed.
Look for the following traits when you look for wood for your raised flower bed:
- Long-Lasting and Rot-resistant – If you want a long-lasting wood (up to 20 years) for your raised bed, you can’t go wrong with Black Locust or Redwood. Cedar is also an outstanding, rot-resistant option. It could easily last for ten years. Douglas Fir is relatively cheap, and it should last at least five years.
- Sustainable and Locally-sourced – You might need to buy the wood at a specialty woodworking store.
- Safe for food crops and soil – As long as the wood is untreated, either wood options should work for your garden bed.
For me, untreated, rot-resistant, locally-sourced wood is the best material for a raised bed. But it may not always be possible to check all these boxes.
For my latest project, I was able to find some untreated pine boards. I am lucky because they are readily available where I live. After only one year, the patina of the wood looks terrific.
I also use pressure-treated wood for large raised vegetable beds and garden structures.
Avoid chemically treated wood material for your raised bed. You don’t want chemicals leaching the soil. Don’t use old railway ties or pressure-treated wood.
Although it isn’t mandatory, you should line the bottom of your raised flower or garden bed. The lining in the bottom is a great way to prevent weeds from growing up from the ground below the bed. The line in the bottom can keep out pests like moles, gophers, and voles.
The proper lining on the bottom of a raised garden bed can make the bed more durable. It can also prevent toxins from leaching into garden bed soil. Avoid plastic lining in your raised flower and garden beds. Plastic blocks drainage and could drown your plants’ root systems.
- Stainless steel rat or gopher mesh – This is the ideal lining for the bottom of a raised bed if you want to keep burrowing animals out. To make sure that the mesh doesn’t shift, staple it in place.
- Wide-mesh hardware cloth – Hardware cloth is great to allow earthworms in and keep burrowing animals and weeds out of raised beds.
- Burlap sack – You might already have a few of these in your garden shed or garage. It is essentially the same material as a potato sack.
- Landscape fabric – Simple and effective solution to control weeds in your yard.
- Cardboard or newspaper – You might be surprised how much protection your garden bed can get from something as simple as cardboard. Lay the newspaper or cardboard on the ground before setting up your beds on top of them.
What is the cheapest way to make raised beds?
There are many types of raised beds. They differ in sizes and uses, some are tiny, and others are large. Unfortunately, raised beds can be expensive. If you are interested in having raised beds in your garden, but without the expense, you might need to build them yourself. The cheapest way to make raised beds is to do it yourself. To keep costs to a minimum, use wood. The best option is to use recycled wood.
How to build a raised flower bed?
When I envisioned an orderly, old-fashioned cutting garden-a separate space dedicated to tall, colorful annuals for indoor bouquets-I knew I needed more than a stylish trug to carry the stems inside. Raised beds would help define the space and add structure to a garden planting that can look untidy later in the season as the flowers come and go.
They’re also suitable for the gardener: it’s easy to amend the soil, and it is possible to have more plants per square meter because there’s no need to walk between rows to harvest or cultivate. Planting in blocks, not rows, means weed seeds have less room to germinate. Raised beds are good for plants, too: the soil warms up quickly in spring and drains freely. And because you’re not walking on the beds, the earth doesn’t become compacted.
I planned to divide an oblong area into four rectangular raised beds, with two 36 inches wide (90 centimeters) paths intersecting in the center.
Coming up with a list of flowers to grow was no problem; deciding how to hold the soil in place required more consideration. Simply mounding up dirt and planting on it creates a raised bed, but if there’s no barrier-plastic, brick, stone, wood, or metal to keep the soil contained, the bed’s depth is limited, and the soil eventually washes away. The Victorians used pretty clay tiles embossed with patterns of twisted rope or acanthus leaves to keep mounded soil from spilling onto lawns or paths. Still, the cost, both for original tiles and reproductions, is dear – ditto for granite blocks.
Heavy railroad ties or pressure-treated lumber used for decks and fences would have worked. Still, I didn’t want to introduce preservatives containing creosote, chromated copper arsenate (CCA), or pentachlorophenol into the soil. In the end, I chose untreated cedar. It resists rot for several years, even when in contact with soil, and fades to a silvery grey over time, a good foil for colorful flowers. More importantly, the cost of a few boards wasn’t going to take a huge bite out of my plant budget.
The next challenge was making straight, sturdy corners that wouldn’t get all out of whack once the wooden enclosures were filled with soil. Alas, the gardeners in my household aren’t carpenters, and the thought of a garden project involving hammers, right angles, and those sharp, pointy things called nails made me fear for my green thumb, as well as my marriage.
In the end, ready-made corners saved the day. I purchased four kits of grow-box corners. Each kit includes four heavy-gauge, galvanized steel corner brackets, screws to fasten the corners to 1″ x 8″ board and, perhaps best of all, easy-to-follow instructions. The genius behind the corners is that they’re hinged and fold flat. The design makes the frames easy to move and store if you want temporary beds. Each kit makes a frame approximately eight inches deep (20 centimeters); there are little projections at the bottom of each steel corner so you can stack as many as four boxes, creating deeper beds.
I decided each bed should be 60 inches wide (1.5 meters), based on how far I could comfortably reach across to the center, important when planting and weeding. The length 10 feet (three meters) of each bed provided generous space for flowers but was not so long that the soil would cause the boards to bow. Instructions recommend boxes be no more than 12 feet long (3.6 meters).
Once my four boxes were in place, I laid landscape fabric on the paths to create a weed barrier, tucking the edges under the boards. I spread eight centimeters of shredded cedar mulch on top of the material. Next, I forked over the soil in the bottom of each box, then added generous layers of shredded leaves, finished and half-finished compost, and old soil from planter and window boxes. Read our article “Should I add worms to my compost pile?”
The following spring, I added two large bales of peat moss and eight bags of cattle manure until the mixture, when raked smooth, was two to five centimeters below the boards’ top edges.
Seeding and planting in the fluffy, rich soil of those four raised beds was a pure pleasure after decades of digging in dense clay. And that started me thinking… are greenhouse kits just as easy?
Making the Flower Beds
1. Before heading to the lumberyard for boards, determine the dimensions for your raised bed. Have 1″ x 8″ boards cut to the desired lengths. (A 1″ x 8″ board is 3/4″ x 7 1/2″, which is what the corner brackets require.)
2. Fasten one side of a hinge to the end of one board using the screws provided. Make sure the top edge of the board is flush with the top edge of the hinge. Attach the other side of the hinge to the end of another board using the rest of the screws. Repeat for each corner.
3. Lift the box into position. Ensure the corners are square by measuring the diagonals-both distances from corner to corner should be the same. Adjust accordingly.