I’ve wanted to grow a small herb garden for the past couple of years, but I just couldn’t work out the right spot for it. The perfect location would be sunny, with nutrient-rich soil and able to contain members of the mint family, which can spread rapidly and overtake gardening spaces. It finally dawned on me that a raised bed herb garden might be the answer.
Raised bed gardens have many benefits and can provide opportunities for gardeners that lack ideal growing conditions for herbs, vegetables and even flowers. They can solve drainage problems in yards with heavy clay or sandy soils. They are the solution to nutrient deficiency problems in yards with infertile soil. They provide a safe alternative in areas with contaminated soil. They can be built on top of the pavement, in vacant lots and in other urban spaces. Hand tools are all that’s required to maintain a raised bed. They can be built to a size and scale that fits your lifestyle. They are more accessible for individuals with limited mobility. Some raised beds are built to waist height to make gardening from a seated position possible. They can even make it easier to contain prolific growers like spearmint, lemon balm, basil, oregano, rosemary, thyme and parsley.
Building your own raised bed garden can be relatively inexpensive or it can get pricey. The key to building a cost-effective raised bed garden is figuring out how much space you need in advance and maximizing the use of the soil you’ll have to buy to fill it.
How much space do I need?
Determining how much space you need starts with adding up the mature sizes of the plants you want to grow.
For example, most mature herbs require about 1-4 square feet of space to grow to maturity. Basil, cilantro, mint, lemon balm and lavender are on the larger size, requiring 4 square feet of space. Thyme and parsley are on the smaller side requiring just 1 square foot of space.
Herbs are also nice because maturity can be a little more subjective. Mint leaves that are harvested when the plant is smaller are generally sweeter. You could likely get away with planting eight different types of herbs in a 4×2-foot raised bed if you stuck with smaller varieties and harvested them before full maturity.
Many garden vegetables are not as flexible with space. One mature tomato or pepper plant will take up about 4 square feet of space. In a 4×8-foot raised bed, you’ll be able to grow about eight tomato and pepper plants with a row of root vegetables or leafy greens in the middle.
Like herbs, root vegetables and leafy greens require less space and it’s up to the gardener to determine the ideal time to harvest them. Additionally, the growing season is long enough for these cold hardy vegetables to plant a spring crop and a fall crop.
Large raised beds are more expensive because they require more soil to fill them up. However, with the same amount of lumber and fewer screws, you can double the amount of space you have for plants. And if you try the hugelkultur gardening technique, you can cut the cost of your initial soil investment.
With two 2x8x12 treated boards, you can build two 4×2-foot raised beds or one 4×8-foot raised bed. If you decide to construct two smaller beds, you’ll have 16 square feet of growing space. If you decide to build just one large raised bed, you’ll have 32 square feet of gardening space. In the same scenario, the two smaller beds will require 10 cubic feet of gardening soil and the larger bed will require 21 cubic feet of gardening soil.
The larger bed has the benefit of being able to grow twice as many plants without requiring any additional hardware and using half as many screws as the two smaller beds. However, you’ll need to spend twice as much on garden soil to fill it up, and your investment in fertilizer and organic matter will be greater over time.
In order to save money, you need to first determine the space you need and then maximize your materials. Although the larger bed in the scenario above costs more, you’re able to double the size of your garden and it’s the better value long-term. However, if you’re never going to grow enough plants to fill it up, the smaller is the more cost-effective option.
How to build a cost-effective raised bed
Materials for two 4×2-foot raised beds
- (2) 2x8x12 treated boards
- (24) 3-inch deck screws
- Planter’s fabric
- 10 cubic feet of raised bed garden soil
Materials for a 4×8-foot raised bed
- (2) 2x8x12 treated boards
- (12) 3-inch deck screws
- Planter’s fabric
- 21 cubic feet of raised bed garden soil
- Circular saw
- Carpenter’s square
- Tape Measure
- Screw gun and drill bit that fits screws
- Staple gun
- Cut boards into four 4-foot lengths and four 2-foot lengths or two 8-foot lengths and two 4-foot lengths. If you decide to go with the larger 4×8-foot raised bed, each board will be cut into one 8-foot and one 4-foot board.
- Bring one 4-foot board and one 2-foot or 8-foot board together to form a 90-degree angle and secure with three screws. Repeat this step until your frame is completed.
- If you chose to build two smaller beds, repeat step two for the second bed.
- Line the bottom of your raised bed or beds with planters fabric. Unroll the planter’s fabric to fit the length of your raised bed, staple it down and cut it off the roll. Repeat until the entire bottom of your raised bed is covered.
- Chose a sunny location that’s near a water source and place your raised bed in its permanent location.
- Fill with garden soil intended for use in a raised bed.
- Plant the herbs, vegetables or flowers you planned for and water them regularly. Raised beds require more frequent watering than traditional gardens.
- They also need multiple applications of fertilizer a year because plants cannot access nutrients from the ground. Synthetic and organic fertilizers are good options to keep the soil nutrient-rich. Adding a half inch of compost every spring and every fall will help boost the level of organic matter in your raised beds.
- How to build a raised bed garden
- How to get the most out of raised beds
- How to build a cold frame in early spring
- How to master the hugelkultur gardening technique
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