Friday, January 19, 2007
Summer Care for Dahlias With blossoms of amazing shapes, sizes, and colors, dahlias contribute bold splashes of color to gardens from midsummer until frost. Their sturdy stems and attractive foliage also make them an exceptional choice for cut flowers. If given full sun with rich, well-drained soil and good air circulation, dahlias are not difficult to grow. A little extra pampering will result in an extra-generous show of flowers. Dahlia varieties that reach more than three feet tall can become top-heavy and topple in the wind. Placing a stake in the hole at planting time is the easiest way to provide support without damaging the tubers. 1. THINNING Once they are in the ground, dahlia tubers usually produce multiple shoots. While you can leave these to grow, thinning will produce flowers of higher quality. Most growers remove all but one to four of these stalks by cutting or breaking the others off before they reach six inches in height. 2. PINCHING In addition to removing excess shoots, pinching (also called stopping or topping) is an important part of early training. After the chosen stalks have grown three or four sets of leaves, pinch out the growing tips of each. This will force the lateral or side shoots at each leaf node to grow, and make the plant bushier. 3. MULCHING, WATERING & FERTILIZING Dahlias like warm soil and will grow most rapidly after soil temperatures have reached 60 degrees Fahrenheit, but will slow or even stop producing flowers when stressed for moisture. Placing a layer of mulch around the plants before the heat of summer dries the soil will conserve moisture and help prevent weeds from growing. Good choices for mulch include shredded leaves, chipped bark, and well-rotted compost. Hand-pull weeds and avoid cultivating the soil, as it is easy to damage the dahlias shallow roots. If rain is lacking, soak the growing plants with at least an inch of water each week, wetting the soil to a depth of one foot. Also, try our Soil Moist! It's great for retaining moisture! Try not to wet the leaves late in the day, because damp leaves can encourage fungus. Dahlias are heavy feeders and benefit from extra fertilizer. In addition to fertilizing at planting time, add nutrients during the growing season by scratching in a time-release fertilizer at midsummer according to the directions. 4. TYING Dahlias that have been thinned to one stalk can be loosely tied to a single stake, using soft twine. For multiple stems, add two more stakes to form a triangular support. Take care to set them well away from the crown to avoid damaging the roots. As the plants grow, loop twine around the stakes at one-foot intervals to support them. 5. DISBUDDING Selective disbudding will produce large flowers with longer stems. The terminal end of each stem will develop three buds. Of these, the central bud will produce the best and largest flower if it is allowed to bloom alone. When the first buds begin to color, use your fingers to pinch out the two side buds. Also remove the small lateral branches growing from the axils of the two sets of leaves directly below the terminal bud to prevent them from forming flowers. Once the terminal bud has flowered, new branches will form down the stem and yield additional flowers. Don't miss Yardiac.com's selection of pruners! Pests and Diseases:Slugs, snails, and earwigs can be trouble to young dahlias and are best controlled by trapping or hand- picking. Sucking pests, such as spider mites, aphids, and leafhoppers, can dramatically stunt growth of dahlias and require close monitoring and swift response with an appropriate pest repellent.Diseases such as powdery mildew can be best controlled with good air circulation. Encourage this by removing the oldest leaves as they become infected. Viruses may stunt plants, or cause leaves to be misshapen or covered with light-colored spots or lines; destroying affected plants will prevent this virus's spread. Yardiac.com also features a great selection of disease control.