Building a Raised Bed Vegetable

Why raised bed gardens? Growing vegetables in the ground can be a real challenge in southeast Florida. In many parts of Miami-Dade County, it’s almost impossible to dig because of the limestone rocks. Also, there can be nematode and soil-borne plant diseases to deal with. That’s why it makes sense to grow your vegetable garden in raised beds! If you’re not thinking you’ll be able to pull the task off, look into companies like and have a shop around their products.

There are various ways you can construct your raised garden bed. Materials you can use include cinder blocks, wood or even decking. You should be able to pick up any of these materials from your local hardware store or you can contact a professional for a composite decking quote. You could even have the decking company build the decking structure for you if you wanted them too. Whatever method you choose, make sure it’s suitable for you and your garden.

Location and Size:

North to south OR east to west. Near a water source or garden hose.
Exposure: A minimum 6 – 8 hours of full sun daily. Plant far away from trees.
Size: Make beds accessible from all sides. Width – young children, beds 3 feet wide. Older children, beds 4 feet wide.
Adults, beds up to 5 feet wide. Length – as long as you need. Hint: Never walk on raised bed soil.


On level ground, lay cardboard or several layers of newspapers directly on top of grass. This prevents grass and
nematodes from getting into your garden soil.

Materials and garden height:

Use landscape timbers, lumber, or cement blocks. If using blocks, the walls of the raised bed don’t need to be
more than 1 layer high. Herbs and vegetables only need a soil depth of 8″ (which is the same height of cement

a raised bed garden using concrete blocks
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Hint: Place the timbers, lumber, or cement blocks over the newspaper or cardboard.


Use bagged composted cow manure or compost. You can also mix together potting “soil” and compost but this is more expensive and not better for growing your plants. If you are creating a large garden, you can buy compost in bulk to save money and you can store them in 8×12 sheds until you’re ready to use them.

Add the soil to your raised bed
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Hint: Avoid using top soil or earth. They can have nematodes, soil-borne plant pathogens, and often does not drain well.

If using cement blocks, fill in the holes. You can plant flowers and herbs in them!

This garden is 2.7′ x 5.2′ (outside dimensions)

Plant your garden the day (or within a day or two) after you add the “soil.” If that’s not possible, cover
the soil with plastic, cardboard, or newspaper to protect against weed seeds.

What and When to Plant:

Fall – spring garden (October – April): most

“summer” vegetables such as tomatoes, beans,
cucumbers, squash, leafy vegetables, herbs, carrots,
peppers, beets, sweet peas, sweet potatoes. Hint:
cherry-type & grape-type tomatoes are easier to grow
and fruit nonstop for most of the season.

Summer or year-round garden: eggplant, okra,
turnip greens, southern peas, sweet potatoes. Tropical vegetables such as calabaza, chayote,

a new raised bed garden
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A recently planted fall garden planted with transplants. One the right, the same garden 6 weeks later! Note rain barrels collecting rain water from the gutter.

Costs (for a child size garden):

Sample supply list for a size of 32″ by 62″ (= 2.7′ x 5.2′) outside measurement raised bed
garden (includes soil for holes in block)
10 (8x8x16 inch) cement blocks @$1.20 each $12.00*
4 (40 lb.) bags composted cow manure @ 1.65 each 6.60
TOTAL $18.60

More expensive garden for a size of 32″ by 62″ outside measurement
10 (8x8x16 inch) cement blocks @$1.20 each $12.00*
3 (1 cubic ft.) garden soil @ $2.97 each 8.91
1 (2 cubic ft.) bagged Flower & Veg. Garden Soil 8.97
1 (40 lb.) composted cow manure 1.65
1 (8 qt.) perlite 3.97
TOTAL $33.85

*or free if scavenged with permission from the “toss” pile at construction sites. If broken, local
cement block manufacturers often sell them at a discount.

Seeds & transplants: figure at least $10.00 for the garden. Not all seeds will be planted (can be
stored indoors for 2-3 years). Growing your own transplants are much cheaper than buying them.

Since these costs include compost, no additional fertilizer is usually needed since compost is a
slow-release fertilizer.

Garden Care:

Watering: – transplants and seedlings need light watering about once a day for the first week or two. Soil should be moist, not wet. As plants get larger, water less often but deeply (so that all the “soil” in the bed is moist). Hint: Test the soil moisture with your finger 2 inches below the soil surface. If dry, water. Avoid wetting the leaves and water in the morning to help prevent plant disease problems.

Fertilizing: – usually not needed if you are using compost. Look for yellowing, stunted plants as an indication that fertilization may be needed. Too much fertilizer can be harmful and inhibit flowering.

Pest Control:
Growing flowers in your garden adds beauty and also provides a nectar and pollen source for beneficial insects (they

keep pests in check). Squish or hand remove bugs and caterpillars. Spray the underside of leaves with insecticidal soap if you see whiteflies, mites, or aphids.


If you are not gardening during the summer, cover the beds with clear
plastic. Leave in place all summer or for at least 6 weeks to kill
nematodes and soil-borne pathogens.

Plant Spacing:

Don’t waste space. Use your raised bed garden space wisely by planting intensely (why have empty space between rows?). Try the square foot, wide row or French intensive method. If using the square foot method, large plants such as tomatoes, peppers, cabbage, eggplants, collards, and broccoli need about 1 square foot per plant. Medium size plants such as leaf lettuce,beans, and spinach can be planted 4 plants per square foot. Smaller plants such as carrots, green onions, and radishes can have 16 plants per square foot.

How to build a raised bed garden (11)
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Save space by trellising vines (except sweet potatoes.)

a trellis for vining plants
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Even squash, cucumbers, and gourds can be grown on a trellis (support the fruit with panty hose or a cloth sling tied to the trellis).

tomato cages
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Use cages for tomatoes (drawing from Va. Tech). Place tall plants on the northern end of the garden to avoid shading smaller plants.

Extending Your Harvest

Harvest the leaves of your herbs, lettuce, collards, and cabbage instead of the whole plant. Your plants will continue to produce more leaves throughout the season. Broccoli will produce side shoots after the main head has been harvested. Grow pole beans instead of bush beans for a continuous harvest. Grow indeterminate-type tomatoes (these continue to flower and bear fruit for months).

Succession planting: for plants that are harvested only once (carrots, radishes, cauliflower, beets,
determinate-type tomatoes, bush beans, green onions), plant a batch of plants every 2 weeks toextend your harvest. As soon as a crop is finished for the season, plant another crop (try
something new!). Once you’ve done so you can look into this outdoor setting sale, get yourself some furniture and enjoy your the fruits of your labor.

Hint: If it’s hot and the sun is intense when you are planting, shade the transplants and seedlings with a fan-type palm leaf (such as a palmetto frond). Place the palm leaf on the south side of the young plants. After a week or two, you can remove the palm fronds.

Not all the seeds in a seed packet need to be planted. Most seeds can be kept indoors for a year or two.

If you want to grow sweet potatoes, place a sweet potato sideways in a shallow bowl with water going about 1/2 way up the sweet potato. After a few weeks, you can take cuttings of the vine and plant the cuttings in your garden.

Additional University of Florida resources: Home Gardens & Landscapes tab and publications tab

Vegetable Gardening in Florida, by James M. Stephens. Available through the UF/IFAS
Bookstore or local book stores.

Written by Adrian Hunsberger, Urban Horticulture Extension Agent and Kathie Roberts, 4-H Extension Agent, University of Florida/IFAS Miami-Dade Extension. Photos by authors unless otherwise noted.
Sept. 2010

Copyright Information:
This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.