With the removal of the spent flowers, those will sparked into life and they will bloom in a week or two. If there are any rotten bulbs on the root clump, cut them away with a sharp knife. She writes about interior decorating and design, travel, film, literature, technology and consumer electronics. Copyright Leaf Group Ltd. // Leaf Group Lifestyle. Some dahlias offers rich, dark colors, while others grow light pastel blooms. Tomatoes In the U.S., dahlias can be left in the ground starting at Zone 8 and warmer. Once spring arrives, separate the bulbs from the main clump and plant them again. Since dahlias have tough, stringy stems, it’s easiest to remove the flowers with sharp scissors, pruning shears, or a knife. This article was co-authored by Lauren Kurtz. While removing dead heads will encourage new buds to begin blooming, removing the buds will delay flower development. Cut back the flower stem to where it meets a main stem. Trim back dahlias after blooms have died to overwinter. Flower buds appear in three's; the middle bud produces the larger bloom. After storing the tubers over winter I repotted them in March this year, started them off in an unheated greenhouse, and moved outside once shoots were around 9" tall - they are about to flower but all are very 'leggy; having grown much taller than last year.. Pinch back the tip growth of plants, like petunias, to force bushiness and more stems which means more flowers. We use cookies to make wikiHow great. If your soil is infested with root knot nematodes, you will need to treat it with a nematicide before you can grow healthy plants. The middle bud in the group of three buds that dahlias grow is the primary, or "leader" bud, and it will produce a larger flower than the other two buds. By using our site, you agree to our. Learn which plants thrive in your Hardiness Zone with our new interactive map! Pulling up Dahlia Bulbs Dig up the dahlia bulbs each fall if you live in a cold region. Lift the flower's petals, then clip the stem under the flower near where it meets the main stem, where two other flowers or buds are located. Place fresh flowers into a container full of warm water immediately. I grew various types of dahlias in pots last year and they were fine. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/e\/ed\/Prune-Dahlias-Step-01.jpg\/v4-460px-Prune-Dahlias-Step-01.jpg","bigUrl":"\/images\/thumb\/e\/ed\/Prune-Dahlias-Step-01.jpg\/aid10108563-v4-728px-Prune-Dahlias-Step-01.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"