Vegetable Gardening with Raised Beds
Vegetable gardening is a great way to grow your own food, but Florida's soils don’t always lend themselves to growing vegetables. Try gardening in raised beds instead. Raised beds are just gardens in a box. A raised bed can help you get higher yields and reduce maintenance in your vegetable garden.
- What Are Raised Beds?
- Benefits of Raised Beds, Part One
- Benefits of Raised Beds, Part Two
- Materials and Cautions
- Construction and Care of Your Raised Beds
- Vegetables for Raised Beds
What are raised beds?
Raised beds are freestanding garden beds constructed above ground level. The "raised" part means that the soil level in the bed is higher than the surrounding soil, and "bed" implies a size small enough to work without actually stepping onto the bed.
A bed should be no wider than four feet so that you can reach into the middle without stepping in it, but the length can be whatever suits the site or your needs. Soil depth should be six inches minimum, and twelve inches if possible. This allows the roots an adequate depth of soil to develop.
Beds can be constructed using a variety of materials, including brick, rot-resistant lumber, landscape timbers, railroad ties, or concrete blocks. Railroad ties lend themselves especially well to stacking for beds as high as one to three feet for gardeners who don’t want to bend over.
Besides being aesthetically pleasing, raised vegetable beds offer many benefits to gardeners. Here are a few.
Improved Soil Conditions
You can provide improved soil conditions for your garden by using a raised bed. Florida soils tend to be sandy and don't do a good job of retaining organic material that plants rely on for nutrition. By adding organic material to your raised bed, you can keep the soil full of nutrients for plants.
Since you don't walk in raised beds, soil compaction, which can hinder plant growth, is also greatly reduced. Reduced soil compaction increases yields of your garden by allowing water and air to move more freely through the soil.
Raised beds can help improve the soil when your yard has less than ideal site conditions. If you have low spots in your garden that tend to pond or have excessive erosion from runoff, raised beds help you avoid those problems. The beds rise above the ponding or erosive areas and still allow water to naturally pass through those spots.
Since you can improve soil conditions in your raised bed, you'll also avoid nematode problems associated with most Florida soils. These microscopic worms can wreak havoc on your plants and reduce yields. You can plant more plants in your raised bed because you don't need the usual space between rows for walking. Raised bed vegetables are planted at higher densities, just far enough apart to avoid crowding but close enough to shade weeds. The result is higher yields!
Raised beds work well for kids and for those gardeners who don't want to have to bend over. It's easier to reach your vegetables in raised beds because they have been raised off of the ground. Building beds one to three feet high also makes gardening possible for those in wheelchairs. Make sure you have wide, hard-surfaced paths in between beds to allow access for wheelchairs.
Raised beds are great for gardeners who want to reduce maintenance in their vegetable gardens. Because beds are a little bit higher, you stoop less to weed, water, and do other garden chores. Since vegetable plants are planted much closer together in raised beds, you have less of a weed problem because the higher density plantings shade out much of the weed growth. Organic or plastic mulches are advised if you want to really reduce weed problems.
Pest control is also easier with raised beds. If burrowing rodents, like moles, are a problem, the bottom of the bed can be lined with poultry wire or hardware cloth. You can even cover beds with bird netting, if you need to keep the birds out, because the narrow dimensions of the beds make it easy to add an overhead frame. The frame can also be used to support covers for frost or freeze protection.
Raised beds also conserve water in your garden. You can use canvas soaker hoses, perforated plastic sprinkle hoses, or low-volume drip-tubing. These irrigation methods work well for dispersing water because of the long, narrow beds. They also reduce disease by directing water to the soil instead of wetting leaf surfaces like you do with overhead irrigation.
You can use just about anything to build raised beds. Your choice of framework can depend on the availability and expense of the construction material and the look you're going for in your landscape. Here are some popular materials to construct raised beds with.
Treated landscape timbers
Used railroad ties
Naturally rot-resistant lumber, such as redwood or cedar
- Other Materials
Synthetic lumber made of recycled plastic
A group of half barrels can make a convenient raised bed for use on a patio
To tie your landscape elements together, match your raised bed materials to other materials used in your landscape. Generally, wood-based products are less expensive than stone or masonry materials. However, you can be resourceful and find used bricks, concrete blocks or other materials at little or no cost.
There are a few things to remember when selecting materials for your raised beds.
- Avoid the use of creosote or pentachlorophenol-treated lumber for bed frames. These chemicals can leach out and injure plants.
- Landscape timbers and railroad ties may have been treated with compounds that contain arsenic. New lumber is no longer treated with those compounds. It's recommended that you try to get new lumber when possible.
- If you're uncertain about the safety of treated lumber, place a heavy plastic liner between the treated lumber and soil used for growing plants to prevent direct contact of plant roots with the treated lumber. Be careful not to tear the plastic when tilling the bed.
There are only a few guidelines to remember in raised bed construction:
- Keep the beds narrow and match their length to the site and the watering system.
- A north-south orientation is best for low-growing crops, allowing direct sunlight to reach both sides of the bed. Beds that will contain taller crops such as pole beans, trellised peas or caged tomatoes might do better on an east-west orientation.
- It's a good idea to use a nice rich potting soil or compost. This gives the plants a great start and you can always add organic matter and nutrients to the soil as you go.
Maintaining Your Raised Bed
One of the benefits of having raised beds is the easier maintenance. But there are a few standard maintenance practices that you will need to keep up with.
Soil in raised beds warms faster and dries out more quickly than soil at ground level, so you need to remember to water your raised beds on a consistent basis. Use irrigation to supplement natural rainfall during dry periods. Soaker hoses or drip irrigation may be placed directly on the bed. Overhead sprinklers can also be used, but because they get the plant foliage wet, they are more likely to spread diseases.
Mulch helps to keep weeds down and soil moist. You can use organic mulches, such as straw or hay, or wood chips placed on landscape fabric. Soil temperatures are lower under organic mulches, less water is lost through evaporation, and weed growth is suppressed. This makes your garden much easier to maintain when these things happen.
Fertilization of plants grown in raised beds is similar to that of plants grown conventionally. For most crops, a complete fertilizer, applied at the rate of one to two pounds per hundred square feet is satisfactory. Organic fertilizers and manures may also be used. For more specific fertilizer suggestions, rely on recommendations based on soil tests. When selecting a fertilizer, look for something with 2% phosphorus or less in accordance with Florida State Law. The exception to this would be when fertilizing edibles; they may need more phosphorus. A soil test will help you determine that.
Clean up beds
At the end of the growing season, you can till your vegetable plants back into the beds. This adds organic matter, but you can also add additional compost for more nutrients. Over time, the soil may become improved enough so that you won't have to till.
Vegetables for Raised Beds
Most vegetables are ideal for raised beds. Try growing lettuce, radishes, strawberries, and many others. Bush type variety vegetables, such as tomatoes, cucumbers, or beans, do great in raised beds. You can also install trellises on your beds for those vegetables that need support. However, certain vegetables, such as squash, melons, and sweet corn might do better in the ground because of the extensive amount of space they require.
See the Florida Vegetable Gardening Guide for what vegetables to grow when and other valuable information on vegetable gardening.
Emily Eubanks, Center for Landscape Conservation and Ecology
With thanks to Dr. Sydney Park Brown, Associate Professor of Environmental Horticulture, UF/IFAS