How to Build a Raised Garden Bed
Build your beds in an area that receives at least five to six hours of sunlight per day – the more, the better! Orient them from north to south to prevent the plants from shading. Beds should be at least a foot wide, but no more than 4 feet in diameter for weeding and harvesting to be manageable. A length of 6 to 8 feet is typical and cost effective. Ten to 14 inches is an ideal height to accommodate strong roots. Leave at least 2-3 feet between the beds for walking and wheelbarrow access.
The brilliance of a plank and rebar design (see above) is that each individual wall is easily replaced. Try wood varieties that are naturally rot resistant, such as oak, cedar, and redwood.
You want dark, rich, and loaded with microorganisms. Fill your flower beds with a mixture of 50-60% good quality topsoil and 40-50% well-aged compost. Before each new growing season, test your soil for pH and nutrient content. You can purchase a kit at most home improvement stores. If your test shows a need for additional nutrients like nitrogen and potassium, increase the levels by working on amendments like bone meal and kelp. Dress the beds with an extra ½ inch of compost later in the growing season to increase organic matter and improve soil health.
If you are building your flower beds in the middle of summer, it is not too late to plant fall crops. Sow seeds like carrots and lettuce directly into the ground, or buy mid-season plants for crops like kale and broccoli. If you’d rather wait until next year to plant, cover the soil of your new raised beds with a mixture of cut grass and ragged leaves in the fall – the material will compost before you’re ready to start in the spring.
Raised beds have fantastic drainage, which is great for the health of the plants, but they dry out quickly. Give your plants a long drink in the early evening, but check them again on hot summer afternoons. If the soil is dry it’s a real burner outside, or if you live in a hot, arid climate, water again. A programmable drip irrigation system (try a starter kit from dripworks.com) is inexpensive and convenient, providing constant moisture directly to plant roots. Invest in a timer component to save money and water.