Dahalias have dazzling flowers

By Melanie Mathieson
Gardening Guru

Dahlias are considered one of the most spectacular garden flowers as they can provide the colour and excitement of exotic species that we are unable to plant in our zone. There are thousands of varieties of dahlias that range, from the showy dinner-plate size to the bright, little single ones. The flower shapes and colour combinations are spectacular and some of the flower petal shapes are unbelievable. From pompom to those with needle like petals it is hard to pick a favourite.
Dahlias range in height from 12 inches to as tall as 8 feet. The flowers can be as small as 2 inches or up to a foot in diameter. You should therefore consider the ultimate goal of what you want from a dahlia, as well as deciding on the available space when choosing the varieties you wish to grow. Novice dahlia growers may want to start by selecting a few plants of varying colors, sizes and types. Dahlias can also make a statement as the focal plant in a large container.
Dahlias should not be planted until all HYPERLINK “http://www.thegardenhelper.com/hardiness.htm” danger of frost has passed and the soil temperature reaches 58-60 degrees Fahrenheit. Make sure the location receives full sun. Dig and prepare a 12 inch diameter by 12 inch deep planting hole. Mix a shovel full of compost and a handful of bone meal into the soil that you removed from the hole. Fill the planting hole with the enriched soil mixture until it is about six inches deep. Place the tuber horizontally in the bottom of the hole with the eye pointing upward. Tall varieties will need staking, so this is a good time to set an appropriate size stake into the ground next to the tuber (near the eye). This will prevent damage which can result if it is added after the tuber has begun to grow. Cover the tuber with your soil mixture and water thoroughly. Avoid excessively wet soil as the tubers may rot. Once the plant attains sufficient height, secure it loosely to the stake. Add more ties as the stem grows until the plant is supported approximately 24 inches below the eventual top of the plant.

A dahlia in bloom is a heavy feeder, so you may want to consider regularly using a water soluble “bloom type” fertilizer starting about a month before the plants begin to bloom. Read the directions carefully before fertilizing. Do not fertilize dahlias after mid-August.
When the plants reach a height of three to four inches, pinch the terminal bud just above the second pair of leaves. This will produce two main stems. When flower buds are visible, begin removing the buds. This will increase the bloom size of the leader bud and improve the flower stem formation. Flower buds come in three’s. The central leader bud will produce the largest bloom. There will be a smaller flower bud on each side of the leader bud. Remove these side buds by pinching or cutting to the base of the leaf axil. Further down the same stem, two more buds will be found in the leaf axils and which should be removed also.
Major pests of dahlias include aphids and slugs early in the growing season and mites in mid- to late-summer. Leafspot and dahlia wilt also can be problematic. Should the leaves yellow in a random pattern it should be removed from the garden immediately and disposed of in the garbage. Also, destroy plants with abnormal or deformed crowns.
Lift dahlias after the first frost or before the end of October. For easier lifting make several cuts into the soil with the fork or spade around the clump and gently pry to raise the tubers intact. Once the tubers are out of the soil, remove as much soil as possible without damaging the tubers and leave them to dry. Cut the foliage off so that all that remains is a three to four inch stem on the roots. Soil may also be washed from the tubers with water. Cut off any small roots. Remove and discard tubers that are damaged or diseased and dust any cut surfaces with sulfur. Make sure you label each one carefully before storing. Place the tubers in wooden flats, bushel baskets, or cardboard boxes that have a few inches of peat moss, sawdust, or vermiculite in the bottom. Then cover them with the same packing material, leaving the stems exposed. A little moisture may be added to prevent shriveling. Place the packed tubers in a dry, 40 to 55 degrees Fahrenheit location. Check tubers in a few weeks and again in January for signs of shriveling or fungal infection. Add a small amount of moisture if shriveling has occurred. Do not expect 100 percent survival.
Bring the tubers out of storage in March or April and locate eyes on each tuber. With a sharp knife, divide the tubers with a portion of crown attached, so that each piece has an eye. If eyes are not evident, place the tubers in moist leaf mold, peat, or soilless mix. In a week or two the eyes will appear. Pot the divisions in a sterilized, soilless mix or porous potting soil with the crown above the potting medium. Provide the potted divisions with maximum sunlight and a temperature of about 55 degrees Fahrenheit. Water when the potting mix dries to a depth of one inch. Good ventilation will help prevent disease.
One of the greatest rewards from dahlias is that they make great cut flowers. For the best cut flowers, cut them early in the day, when they are first opened. Immediately place them in water which has set for 24 hours to allow any chlorine to dissipate and change the water daily. Cut dahlias will last from 5-7 days.
Stop at your local nursery supply and buy some dahlia tubers or potted plants and soon you’ll be dazzling friends with your dahlias.