Dos & Don'ts of Raised Bed Gardening

Question: Last year I tried a raised bed vegetable garden, but it didn't produce any vegetables. What am I doing wrong?  Seedlings and plants grew very slowly, not much at all or died.

Congratulations on experimenting with raised bed gardening, even though the results were less than desirable. Nothing ventured, nothing gained! There's also nothing as tasty as tomatoes, beans, and squash fresh from the garden. Let's go over some basics that should help you achieve successful yields in the future.

What are Raised Beds?
Raised beds are garden plots above ground level and can be made either by mounding soil into a bed six to eight inches high without side supports or by buying or building a frame out of wood, plastic planks or other materials. These beds are typically small enough that the gardener can walk around outside the bed and tend to all the plants without stepping into the garden bed.  An ideal size for a raised bed is 3 to 4 feet wide with the length to suit the space available. It is most often rectangular in shape and generally 8 to 12 feet long.  The bed may be as much as a foot deep, depending on the type of plants being grown.

The History of Raised Beds
The practice of using raised beds dates to medieval times when farmers used wattle fences (walls of woven limbs and branches) to contain their gardens. In the 18th century, the Parisian market gardeners grew vegetables in raised beds, using the plentiful horse manure of the time as fertilizer. The concept gained popularity again in the early 1970's when gardeners built raised beds with freestanding frames to encourage higher crop yields on smaller house lots. With healthy soil and proper care, raised beds can produce a large harvest in a small space.

The Benefits of Raised Bed Gardening

  1. More control of the soil quality and better soil drainage: you will need to add garden soil or amend existing soil to improve soil structure.
  2. No need for pathways between rows: crops can be planted more densely, resulting in higher yields.
  3. Less plant damage and soil compaction from foot traffic: you can work outside the perimeter of the raised bed instead of stepping into your garden.
  4. Convenient access to all areas of the raised bed: especially helpful for gardeners with limited mobility.
  5. Easy maintenance: the increased height of the bed reduces the distance to reach or bend and squat to plant, mulch, weed, and harvest.
  6. Longer growing season: raised beds warm up quicker in the spring and cool down slower in the fall.
  7. Can be converted to a cold frame: by covering with hoops for frost protection, you can create a longer growing season.
  8. Works well in limited space: you do not need a large plot of land to have a bountiful harvest!

Building A Raised Bed
Before you begin, consider the following important decisions: the location, dimensions, up-front time, work, and budget. Initial planning and preparation is the key to success and saves time in garden preparation in subsequent years. Be sure to consider all the following factors for your raised bed vegetable garden:

  • site requirements: should have at least 6 to 8 hours of full sun per day, access to water, loose and well-drained soil, and be positioned some distance from buildings, trees, and shrubs to avoid competition for water and nutrients.
  • dimensions of a raised bed: usually 3 – 4 feet wide and above ground with a square or rectangular shape. The length depends on space available and the quantity and type of crops to be planted. Depth is typically 8 to 12 inches deep but can be greater.
  • raised bed frame: can be untreated or rot resistant wood (cedar or redwood), stone, brick, plastic, or other materials.
  • soil sources: matter, so if you take soil from your yard to fill the raised bed, be sure to get a soil test, so you will know amendments needed. If purchasing garden soil, mix it with organic matter like compost or manure to ensure a healthy soil and healthy plants.
  • Perimeter space: outside the raised bed should be reserved for pathways from which the gardener will work. Many of the references below cover detailed specifications, plans and helpful suggestions.

What Can Go Wrong?
To ensure a healthy crop of vegetables, you will want to ensure that:

  1. The site is conducive to growing vegetables. If the site does not get enough sun, for example, plants will not thrive.
  2. The soil is amended with organic matter and other nutrients and prepared properly, with weeds controlled. Poor soil hinders seed germination, root growth, nutrient supply, and results in poor plant health and reduced yield. Compacted soil can also inhibit plant growth.
  3. The right seeds and plants are selected for your plant hardiness zone and planting guidelines are followed. Plant at the correct depth and spacing, following plant and seed packet directions. For Virginia, consult the home garden vegetable guide for detailed information. Some plants are not suitable for raised beds because of their size or space requirements.
  4. Proper and timely watering is necessary, as raised beds dry out faster than in ground gardens. Drip tubing or soaker hoses can be a good option. Always water at the base of plants helps prevent disease.
  5. Mulching around plants helps control weeds and conserves moisture.
  6. When starting from seeds, thin seedlings per the seed packet directions to keep plants from becoming leggy and weak.
  7. Leaves should touch at maturity, but not overlap or plants may be crowded out or not receive enough sun.

Hopefully, you now have a better understanding of how to have a successful raised bed vegetable garden and to avoid a repeat of your failed vegetable garden of last year.  Maintain a garden journal to track successes and failures throughout your gardening season. Next year you will need this handy reference to continue experimenting. Here's to a successful harvest for years to come!

References:

"Container and Raised-Bed Gardening," Alex Niemiera, Virginia Tech Cooperative Extension, Publication 426-020, 2018.

"Intensive Gardening Methods," Alex Niemiera, Virginia Tech Cooperative Extension, Publication 426-335, 2018.

"Raised Beds for Vegetable Production," Dr. Ajay Nair, Assistant Professor, Department of Horticulture, Iowa State University, Extension & Outreach, Small Farm Sustainability Newsletter, March 2016.

"Raised Beds vs. In-Ground Gardens," David Berle & Robert Westerfield, University of Georgia Horticulturists, College of Family & Consumer Sciences, College of Agricultural & Environmental Sciences, University of Georgia Cooperative Extension, Community & School Garden Series, Circular 1027-3, Feb. 2013.

"Starting a Home Vegetable Garden," Ralph Morini, Piedmont Master Gardener, The Garden Shed, Vol. 7 No. 2, Feb. 2021.