Dahlias are stunning flowers that come in a wide range of colors, shapes, and sizes. They are easy to grow from tubers and will bloom from midsummer to fall, adding beauty and charm to your garden. In this article, we will show you how to plant and grow dahlias successfully, following these simple steps:
- Choose the right variety for your space and preference. Dahlias are classified into three main categories based on their size: large, medium, and small. Large dahlias can grow up to 4 feet tall and have huge flowers up to 15 inches across, such as the “Dinnerplate” variety. Medium dahlias, also known as border dahlias, are between 1 and 2 feet tall and have flowers between 4 and 8 inches across. Small dahlias are between 10 and 20 inches tall and have flowers between 2 and 4 inches across. Dahlias also come in many colors, from white to black, and some are bicolor or variegated. You can choose the variety that suits your taste and the space you have available.
- Buy fresh and healthy tubers from a reputable source. You can find dahlia tubers at your local nursery or garden center, or order them online from reliable websites. Look for tubers that are firm, plump, and have pink “eyes” or buds on them. Avoid tubers that are wrinkled, rotten, or have no eyes.
- Plant your tubers at the right time and place. Dahlias need warm soil and full sun to grow well, so wait until the soil temperature reaches 60°F (15°C) and the danger of frost has passed before planting them outdoors. If you live in a cold climate, you can start your tubers indoors in pots about a month before the last frost date, then transplant them outside when the weather is warm enough. Choose a location that gets at least 6 hours of direct sun a day and has well-drained, fertile soil. You can improve your soil by adding compost or manure before planting. Dig a hole about 6 inches deep and wide for each tuber, and space them about 18 to 24 inches apart for large varieties, 12 to 18 inches apart for medium varieties, and 9 to 12 inches apart for small varieties. Place the tuber in the hole with the eyes facing up, and cover it with 2 to 3 inches of soil. Do not water the tubers right after planting, as they may rot.
- Stake your dahlias for support. Dahlias have weak stems that may break under the weight of their heavy flowers, especially in windy conditions. To prevent this, you can stake your dahlias when they are about a foot tall, using bamboo poles or metal stakes that are at least as tall as the mature plant height. Insert the stake about a foot away from the plant, being careful not to damage the tuber, and tie the stem loosely to the stake with twine or soft cloth.
- Water and fertilize your dahlias regularly. Dahlias need consistent moisture to thrive, but not too much that they become soggy. Water your dahlias deeply once or twice a week, depending on the weather and soil conditions. You can check the soil moisture by inserting your finger about an inch deep into the soil; if it feels dry, it’s time to water. Dahlias also benefit from regular feeding with a balanced fertilizer (such as 10-10-10) every two weeks during the growing season. Apply the fertilizer according to the label directions, avoiding contact with the foliage.
- Pinch and prune your dahlias for more blooms. Dahlias produce more flowers if you pinch off the growing tips of the main stem when they are about a foot tall. This will encourage branching and more flower buds. You can also prune off any weak or damaged stems or leaves throughout the season to keep your plants healthy and tidy. Deadhead spent flowers regularly to prolong blooming and prevent seed formation.
- Protect your dahlias from pests and diseases. Dahlias are relatively pest-free, but they may attract some insects such as aphids, thrips, spider mites, or slugs. You can control these pests by spraying them with water or insecticidal soap or picking them off by hand. Dahlias may also suffer from some fungal diseases such as powdery mildew or botrytis blight, which cause white or gray patches on the leaves or flowers. You can prevent these diseases by watering at the base of the plant rather than overhead, providing good air circulation around the plants, and removing any infected plant parts.
- Dig up and store your tubers for winter (optional). If you live in a cold climate (zone 7 or lower), you will need to dig up and store your dahlia tubers for winter, as they will not survive the freezing temperatures. You can do this after the first frost has killed the foliage, or before the ground freezes. Cut off the stems about 6 inches above the ground, and carefully lift the tubers with a fork or spade, shaking off any excess soil. Label each tuber with the variety name and color, and let them dry in a cool, airy place for a few days. Then, pack them in boxes or crates filled with peat moss, vermiculite, or sawdust, making sure they do not touch each other. Store them in a dark, cool, and dry place, such as a basement or garage, where the temperature is between 40 and 50°F (4 and 10°C). Check them periodically for signs of rotting or shriveling, and discard any bad ones. Replant them in spring when the soil is warm again.
Dahlias are rewarding plants that will brighten up your garden with their colorful and diverse flowers. By following these tips, you can enjoy growing dahlias year after year.