"With a deck garden, you don't have to worry about the work side of gardening," says Sam Cotner, Ph.D., who has learned a lot from the deck garden he designed and installed in his home landscape. (See March/April 95 issue of TEXAS GARDENER) "I'm convinced that with my deck garden, I've overcome all my gardening problems," he adds.
As head of the Horticulture department at Texas A&M University, Sam Cotner already spends much of his time teaching others how to make the most of their gardens. But now that he has perfected his deck gardening system, he is ready to share all of his experience and techniques with other Texas gardeners. Like many others around the state, the soil near Sam Cotner's home left a lot to be desired when it came to good gardening. "Since I had such poor existing soil, I decided to build raised beds, instead of doing a traditional garden in the ground like I had done in the past," he explains.
After building a number of different sized planting boxes out of 2-by-l0 CAA pressure-treated lumber, Cotner arranged them in an eye-pleasing pattern. "The design is my own. I set them out after I built them and then decided to put something slightly different between the beds once I had a layout I liked," says Cotner.
"After considering all my options, I went with a blend of wood decking, bark nuggets and brick. This combination looks good and requires less on-going maintenance than grass or gravel paths," he adds.
Since he built his original deck garden, Cotner has added an additional section for fruit trees. "I added a small fruit orchard consisting of two peach trees, two plum trees, two grapevines, two apple trees and one apricot tree," says Cotner. "These additions add a nice vertical touch to the garden, but I wish they had a longer fruiting season like vegetables do," he says.
"Now that time has gone by, I also need to pressure wash the deck garden walkways just like you would a regular deck," says Cotner. "I've also discovered that I could have done a better job leveling the ground before I installed my deck garden. I should have spread a load or two of top soil over the ground before I put in the beds so the area would drain better," he adds. "Experience has also shown that you shouldn't make your beds wider than 4 feet across. Otherwise, you won't be able to reach to the center of the bed from the path to tend your vegetables there," he explains.
Another thing to keep in mind as you are designing your deck garden is its beauty, as well as functionality. "We live out here in our deck garden," says Cotner, describing his creation as a living, enjoyable deck complete with barbeque pit, chairs and flowers.
Building your deck with more than one level can add interest, as can incorporating old or distinctive bricks as part of the walkways. Flagstones can also be used, as can concrete pavers, or any other easily installed, hard-surfaced material that will block weed growth between the planting beds. Installing the wood decking at different, yet complimentary angles throughout your deck garden is another way to increase its design appeal without spending extra money. Also, as you are building both the wood decking and the planting boxes, try using screws, rather than nails, as they will hold your deck garden together much longer than nails. "Building a deck garden can take some time, but the rewards sure are worth it," explains Cotner. As anyone who has ever struggled with stray Bermuda grass or nut sedge will tell you, keeping weeds and grass out of your planting beds is also essential. "I put plastic in the bottom of the planting beds before backfilling them with my soil mix," says Cotner. Plastic seems to work better than the various fabric-like "weed barriers" sold in nurseries and home-improvement centers. While these fabric-like sheets are penetrable to water, they can allow troublesome weeds and grasses to grow up into your planting beds. Plastic also does better than layers of old newspapers, as weeds also seem to find their way up through the papers and into the soil in your deck garden beds.
Since good soil, or lack thereof, is often the reason raised beds are used to begin with, it is important to start with the right soil mix. "There's no dirt as such in my deck garden," says Cotner. "Instead, I use a blend that's one-third sandy loam and two-thirds peat moss," he adds. This well-drained soil is easy on both plants and gardeners.
"I'm convinced that growing a strong root system is one of the keys to gardening success in Texas," says Cotner. Loose soil allows plant roots to grow freely and is much easier to work with than heavier soils with lower levels of organic material. "I've traded in my big tiller for a small tiller and a spading fork," says Cotner. "Working in a deck garden with its raised beds of loose soil saves your back, but still allows you to grow anything you would normally plant in a traditional garden," he adds.
While loose soil is easy to work with, it also dries out faster than heavier mixes, so you will want to make sure you have a dependable supply of water for your deck garden. "Water is one of our most precious natural resources," says Cotner. "When I first put in my deck garden, I watered it with rain water stored in a 50-gallon tank. Unfortunately, during the hot, dry summers we've been having, that 50 gallons of rainwater didn't last long," says Cotner. "To solve this problem, I put my deck garden on my landscape's sprinkler system. I still use the bi-wall drip system fed off lateral lines to get the water to the plants-I always have a dependable supply of water for my deck garden," he says.
Although he is not getting his water out of the 50-gallon tank, Cotner still uses the tank and the pipes connecting it to the garden beds for fertilizing his garden. "All you have to do is add a water soluble fertilizer to the water which is kept at a constant level in the tank with the help of a float similar to those found in commode tanks," he says.
"As you're installing your watering system, make sure you glue all the pipe joints securely," says Cotner. "Digging up your pipes after you've already covered them up with decking is no fun. I learned that the hard way," he adds. While it is easy to get in a hurry while joining your pipes with couplings, it is better to take your time and make sure they are joined securely. Pipes that are not glued well can easily come apart in the future as water pressure or shifting soil presses them apart.
"Maintaining even soil moisture levels and good fertility are just two of the sound gardening practices employed in the deck gardening system," says Cotner. These principles are just as important in traditional gardening, but with a deck garden, they are easier to implement.
It is also important to rotate your crops, planting them in different areas of the garden each year. "In addition to rotating my crops, I also let one garden bed lie fallow each season. That's where I put all my garden trimmings all season long, then till everything under, incorporating all the organic matter into the soil," says Cotner. More organic matter can be added to the beds over time, but be careful not to over-do it. "If you put in too much organic matter, it can have a tendency to water-log your soil," says Cotner. "This can especially be a problem if the underlying ground is poorly drained and usually holds water when it rains," he explains. You do not want to end up with so much organic matter that the soil mix ends up acting like a sponge, rather than a sieve.
Another way to get the most out of your deck garden is through succession planting. "You can also get more out of your garden by going up in some of the beds," says Cotner. Growing cucumbers, beans and other vining plants on trellises or netting keeps these plants up off the soil, leaving plenty of room there for other, more low-growing types like radishes, chives, lettuce or even flowers. "I used to say 'If you can't eat it, don't grow it', but now I've changed my tune," says Cotner. Depending on the season, all types of flowers, including dianthus, pansies and zinnias, can be planted alongside your vegetables. Flowers not only make your garden more decorative, but they also make great additions to the inside of your home in cut arrangements. Mulching your flowers, as well as your vegetable plants, can help to conserve soil moisture and limit weed growth in your deck garden beds.
"I had an exceptional garden this past spring," says Cotner. "Growing plants in a deck garden makes things a whole heck of a lot easier. I don't have nearly the weed, insect or disease problems I've had before. I just love it. The deck garden has made gardening enjoyable," he adds.