By Megan Fulweiler
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Growing painsThe one drawback is that dahlias require a bit of extra work at the beginning and end of the season. They’re bushy perennial plants grown from tubers, with the exception of exhibition dahlias, which are generally grown by rooting cuttings. And the tubers (they look like sweet potatoes) need to be lifted in the fall, carefully stored and replanted in the spring.
Rumored to grow anywhere, dahlias thrive in a good home. “Dahlias, like most plants, are more successful when they’re planted in compost-enriched soil,” says Blithewold horticulturist Gail Read. “More and more, research is showing us that trying to make up for a lack of nutrients with numerous feedings later can actually weaken a plant’s immune system.”
Lighten heavy soil by adding well-rotted manure, humus, mulch or a combination. Raised beds are a quick cost-effective solution and a popular fix where space is tight. If you’ve prepared your bed the previous fall, always the best idea, perk up the soil with a good tilling to a depth of six to ten inches in the spring before you begin to work.
Keep in mind when you’re choosing a site, dahlias also need water and plenty of it. They don’t like being left hot and dry. Select a locale that’s handy to the hose with good drainage (dahlias also prefer not to stand in water) to ease chores. As for light, full sun is ideal, although Blue Star will tolerate a bit of shade or, at least, a few hours less of full sun.
Crowd controlFor spectacular results, some gardeners insist on giving dahlias a healthy plot all their own. The idea is to free the plants from having to compete for nutrients or space. Like children who’ve been gathered in one spot, they’re also easier to monitor when they’re corralled.
Award-winning dahlia growers and longtime members of the Rhode Island Dahlia Society, Joan and Larry Additon devote a generous portion of their North Kingstown backyard solely to dahlias with several smaller dahlia-satellite gardens taking up the slack. In total, the Additons watch over some 400 plants, and every one of them, it seems, is more beautiful than the last.
“Our list is always changing because we’re constantly trying new textures, forms and colors to see what will work the best and what we like the most,” says Joan.
At Blithewold in Bristol, Read and her staff take another approach. Rather than set them apart, they group their gorgeous dahlias with a variety of flowers in several drop-dead-gorgeous displays. The site of many a ceremony, the opulent Wedding Garden, for example, is a heartfelt recipe of salvia (indigo spires) with both yellow and white dahlias along with white phlox and pale Japanese anemones.
Whatever your scheme, take time to make a plan first. The classic rules of thumb won’t let you down: big divas to the rear, smaller sorts up front. And a mass of color is always more visually appealing than a hodgepodge.
Digging inAlthough dahlias can be given a jump-start by making divisions of last season’s tubers and potting them up in a greenhouse or coldframe, the most common method is to set tubers out in the open garden. In our area, it’s best to get started in late May or even early June after all danger of frost has passed. Dahlias don’t like chilly soil so figure after the lilacs have faded and the days have begun warming.
Depending on the variety, dig holes about six to twelve inches deep. Dwarf dahlias will require only about three-to four-inch deep holes. The average spacing distance ranges from around twelve to twenty-four inches for the supersize flowers. Space them too close and neighbors could intertwine, making the fall dig-up twice as difficult. The tighter plants are bunched, the less air circulation they’ll get, especially at the bottom, which also makes them more susceptible to powdery mildew.
With a sharp knife, divide your tubers into clumps of at least three eyes (buds visible at the beginning of each tuber). Lay them sideways in the hole and cover with four to five inches of soil. Don’t water now, unless it’s a particularly dry spring.
Instead, wait until the plants begin to grow. Every few days should be enough. To prevent diseases, and to conserve water, give them a hearty drench with a soaking hose.
Ground workMinus a tap root, weighty dahlias topple easily in a storm. If you’re longing for large specimens such as, say, Eveline or Trudy’s Favorite, you’ll also need to do some staking. It’s best to set the stakes, about one foot taller than the expected height of the plant, at planting time. “Stake when the plants are already underway, and you could easily impale the tubers and permanently damage them,” says horticulturist Jim Donahue at Green Animals Topiary Gardens in Portsmouth, where a generous new dahlia garden was recently introduced.
Serious growers tending rows and rows of dahlias use any number of strategically placed stakes and ingeniously weave the whole lot together. But most backyard gardeners can get by using one or two wood or bamboo stakes per plant. Wire tomato cages, set in place early, will also work for small to medium height varieties. Spray the cages and stakes dark green first to make them disappear. When the dahlias are approximately a foot tall, begin securing them to their supports with soft twine or bits of torn cloth. Then, keep tying them at about every eighteen to twenty-four inches as they zoom along. Be sure to anchor weatherproof labels to the stakes to make identification easier.
It goes without saying that good dahlias come from good tubers. Forego the penny-saving bags at your local hardware store. Reliable nurseries and catalogs along with local dahlia sales are a far better source and also a great way to glean information.
Maintenance maniaIn addition to watering, lush dahlias need to be protected from pests. Earwigs and slugs are two of the most common and visible nuisances around our yard. If you aren’t squeamish about such things, both are easily picked off by hand. Ancient tricks like a saucer of beer left out at night and a sprinkling of ashes also deter slugs. So do lizards, snakes, frogs and toads if you can entice them to hang out. As for earwigs, Philip Damp, the author of Grow Dahlias With Us, a National Dahlia Society publication, suggests the “pot on the stick” method. “Place a small pot on top of your marker cane, and each morning you will find it harboring several earwigs,” he claims. “You can destroy them by popping them into a tin of paraffin or a strong insecticide.” Check with your local garden center or URI’s Master Gardeners (www. urimga.org) for other, preferably organic, methods of bug and mildew control.
Happily, the more dahlias you pick, the more seem to come. But, disbudding improves quality. The Additons carefully pinch off the two side buds below the terminal bud along with the side shoots further below to achieve an astonishing, perfectly shaped blossom full of color on a long, strong stem.
Pinching off pea-size blossoms until mid-August can also help postpone a flow-er display, great if you have a date for a party looming ahead.
Don’t be intimidated by the thought of doing it wrong. Dahlias are tough nuts. Come August, you can pinch some and pick some daily, all in a willy-nilly fashion, and your house will stay full of bouquets for weeks. The only caveat? You must systematically deadhead all the spent blossoms to prolong the flowering.
Time for bed“Ideally, the tubers should remain in place until frost. That infusion of cold swells the tuber making it fatter and more ready for storage,” says Read.
Remove the stakes, cut back the hollow bamboo-like stems to three to four inches above ground and gently pry the tuber clumps from their nests. This will go more easily if you make several cuts into the soil around each plant with a fork or spade. Lay the clumps in the sun and allow them to dry out for a day or two. Then carefully shake off the dry soil discarding any dahlias that look diseased.
The Additons store their tubers by the shelf-full in handsome wood boxes specifically designed and built by Larry for this purpose. But bushel baskets, wood flats or even cardboard boxes will do. Fill the containers with a few inches of packing material such as sawdust or vermiculite. Tuck in the tubers and add several inches of the same material on top to keep them cozy. Label each box. Include the name of the plant as well as the color and height.
Spirit your treasures away in a dry location, one that will remain at about forty to fifty-five degrees. A corner of the basement or a tool shed is perfect, not too hot to cause sprouting but not so cold to allow freezing. “If we’re really worried about temperatures, we’ll sometimes cover the boxes with blankets,” says Read. That’s all there is to it. And just think: come May, you get to start the whole wondrous process, homely tuber to terrific flower, all over again.
Pretty potsDahlias with their opulent leaves and lustrous flowers look fabulous in a pot, either solo or with partners. For the proper container size, check nursery labels and catalogs for the plant’s full-grown dimensions. Author Sydney Eddison (see book list below) likes deep rose-pink Fascination, she explains, with an ultimate height of three feet and an eighteen-inch girth nestled in a thirteen-by-fifteen-inch pot.
Any holder that keeps the potting mix in and allows the water to seep out, though, will do. (Avoid using garden soil, which is too heavy and dense.) The most important element is drainage. “Alternatively, if you find an interesting artifact that has too many holes, you can line it with black plastic, then poke holes in the plastic,” Eddison writes.
A medley of orange-red Ellen Houston, coleus and sweet potato vine? Or small red Bishop of Llandaff all by itself? Use your imagination. For fun, match your blooms to the color of your outdoor cushions. Or mix different shades in matching pots. If there’s any danger of wind, taller dahlias will need stakes. Set the stakes or bamboo poles in place when you fill your container. To get a jump on summer, you can also start the pots indoors and move them out when the weather is right. A dash now and then of water-soluble fertilizer will keep plants hopping.
In fall, lift your tubers and store them away for next summer. Or cut the stems back to about six inches and store the whole pot in a frost free spot. Plastic pots mimicking terra cotta and stone will look stunning — no one will know — save your back and make transporting easier.
Team workThere is no better way to gather information than from fellow gardeners.
The Rhode Island chapter of the American Dahlia Society holds monthly meetings. Contact membership chairman Abby Barber, 1411 Shannock Road, Charles-town, 02813.
What Not to Miss: The chapter’s annual plant sale and tuber auction, Sunday, May 20, Cold Spring Community Center, 39 Beach Street, North Kingstown. Festivities begin at 1 p.m. Admission is free. Information: 294-4734.
Green Animals Topiary Gardens, 380 Cory’s Lane, Portsmouth, 683-1267, www.newportmansions.org. The dahlia garden was created in conjunction with the Rhode Island Dahlia Society. Check the website for information on upcoming dahlia tours.
Blithewold Mansions and Gardens, 101 Ferry Rd., Bristol, 253-2707, www. blithewold.org. Visit the gardens to see how dahlias can work in your borders and for information on future dahlia-related events.