The Garden Column: Dahlias
Sunday, August 09, 2009
By Juergen Jaenicke, MG
(Courtesy Cornell Cooperative Extension)
Dahlias contribute bold splashes of color to gardens from midsummer until frost with blossoms of amazing shapes, sizes and colors. Their sturdy stems and attractive foliage also make them an exceptional choice for cut flowers. 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.
The dahlia is a very prolific plant variety that is easily propagated. There are three popular ways to do it: by dividing tubers, rooting cuttings, and by planting seed. Only the first two methods will provide a bloom exactly like the parent. Seed may provide a bloom similar to the parent but will never be true: being a product of the genes of two dahlias, blooms produced may differ from both parents in color, size and petal form. Thus, new varieties are formed from seed.
The most popular way of propagating the dahlia is from tubers that develop during the growing season. The tubers are dug up and stored over the winter in a cool, dry and dark place, ideally at 40 degrees Fahrenheit. Small growths called “eyes” should develop in the crown areas of the dahlias (the area where the tuber is joined to the stem). An eye on the tuber is the start of a plant for the new growing season. Each clump of tubers can develop many such eyes. However, if a tuber does not form an eye, it will not develop into a new plant.
You can divide tubers in the fall or in the spring. It is probably easier to physically divide the tubers in the fall since the tubers are still fairly soft as soon as they are dug. If you have never divided before, although the tubers become harder during the months of storage, spring is the best as it is the easiest time to see the eyes from which the new sprouts will form. If eyes are difficult to see, try dividing the clumps in half or quarters.
You may wish to warm the dahlias for two or three weeks at 65-75 degrees Fahrenheit before dividing them in the spring, in an attempt to have the eyes form more clearly. An other excellent way to start eyes forming is to take the entire clump and place it on a bed of moistened promix for two or three weeks. The “benched up” or “boxed up” tubers should be kept at 65-75 degrees Fahrenheit for two to three weeks until the eyes form.
To accomplish the actual divisions only a few tools are needed. A sturdy four to six inch solid steel shafted knife with wood riveted handle is best for the large clump divisions. A small hammer is necessary to tap the knife into some of the thick, hard clumps. A good strong bypass type of pruning shears (as opposed to the anvil type) can be used to divide almost all tubers with eyes. A 2 ½ to 3-inch small pocketknife or box cutter can be used for the smaller more delicate divisions. Some professional growers recommend using a curved linoleum knife for tuber divisions. Please be careful and use leather work gloves as you divide them. To avoid breaking the slender and delicate necks of the tubers as you handle them, a sock filled with sand is a helpful aid to place the clumps on.
There are several Dahlia Clubs here on Long Island once you get into Dahlias you will have plenty of opportunities to join one of the, exchange bulbs and receive all the help you can imagine. Good Luck!
(Courtesy Cornell Cooperative Extension)
Dahlias contribute bold splashes of color to gardens from midsummer until frost with blossoms of amazing shapes, sizes and colors. Their sturdy stems and attractive foliage also make them an exceptional choice for cut flowers. 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.
The dahlia is a very prolific plant variety that is easily propagated. There are three popular ways to do it: by dividing tubers, rooting cuttings, and by planting seed. Only the first two methods will provide a bloom exactly like the parent. Seed may provide a bloom similar to the parent but will never be true: being a product of the genes of two dahlias, blooms produced may differ from both parents in color, size and petal form. Thus, new varieties are formed from seed.
The most popular way of propagating the dahlia is from tubers that develop during the growing season. The tubers are dug up and stored over the winter in a cool, dry and dark place, ideally at 40 degrees Fahrenheit. Small growths called “eyes” should develop in the crown areas of the dahlias (the area where the tuber is joined to the stem). An eye on the tuber is the start of a plant for the new growing season. Each clump of tubers can develop many such eyes. However, if a tuber does not form an eye, it will not develop into a new plant.
You can divide tubers in the fall or in the spring. It is probably easier to physically divide the tubers in the fall since the tubers are still fairly soft as soon as they are dug. If you have never divided before, although the tubers become harder during the months of storage, spring is the best as it is the easiest time to see the eyes from which the new sprouts will form. If eyes are difficult to see, try dividing the clumps in half or quarters.
You may wish to warm the dahlias for two or three weeks at 65-75 degrees Fahrenheit before dividing them in the spring, in an attempt to have the eyes form more clearly. An other excellent way to start eyes forming is to take the entire clump and place it on a bed of moistened promix for two or three weeks. The “benched up” or “boxed up” tubers should be kept at 65-75 degrees Fahrenheit for two to three weeks until the eyes form.
To accomplish the actual divisions only a few tools are needed. A sturdy four to six inch solid steel shafted knife with wood riveted handle is best for the large clump divisions. A small hammer is necessary to tap the knife into some of the thick, hard clumps. A good strong bypass type of pruning shears (as opposed to the anvil type) can be used to divide almost all tubers with eyes. A 2 ½ to 3-inch small pocketknife or box cutter can be used for the smaller more delicate divisions. Some professional growers recommend using a curved linoleum knife for tuber divisions. Please be careful and use leather work gloves as you divide them. To avoid breaking the slender and delicate necks of the tubers as you handle them, a sock filled with sand is a helpful aid to place the clumps on.
There are several Dahlia Clubs here on Long Island once you get into Dahlias you will have plenty of opportunities to join one of the, exchange bulbs and receive all the help you can imagine. Good Luck!