Growing Dahlias: The Basics
Dahlias are pure joy. They come in a wide variety of shapes, colors and sizes to fit the needs and dreams of cut flower growers and gardeners alike. It may seem intimidating to grow them at first, but with a little know how and attention, it's quite easy. Dahlias originate from Mexico. They are bushy herbaceous plants that produce tubers (much like potatoes,) which help create their root systems and provide them with energy upon planting. The tubers were originally grown by the Aztecs as a food source, but nowadays, they are best known for their colorful and unique blooms that grace the gardens of the World.
Because dahlias originate from Mexico, they have enjoyed and adapted to a warm climate. This makes them an annual in most regions. While they can be grown from seed, most often they are grown from tubers because their seeds rarely produce a genetic replica of the parent plant. Thus, by growing dahlias from tubers you ensure an identical genetic clone of the original parent plant.
Basic Care Tips:
Dahlia tubers are much like potatoes. They provide water and energy to the plant early on in life and they have "eyes" just as a potato does. The "eyes" are located at the crown, or shoulder of the tuber. Once planted, shoots will sprout from these "eyes," eventually producing stems that shoot up above ground and grow flower blossoms. The remainder of the tuber helps to create roots while underground. When first receiving your tubers, it may be difficult to locate the eyes. This is because most dahlias need to "wake up" in order to form visible eyes. To "wake up" dahlia tubers, they must be placed in temperatures above 55 degrees Fahrenheit. The time at which it takes for tubers to wake up depends on variety, some taking up to eight weeks to produce their first eyes. One of the joys of growing dahlias is that each year, a grower can become better acquainted with individual varieties, thus with time becoming a better dahlia grower.
Planting Dahlias
Dahlia tubers should be planted in the spring after risk of frost has passed. Once planted they can take 2-8 weeks to sprout. Do not water them until they are 6-12" tall. In doing so early, you run the risk of causing them to rot before they have rooted. They can be grown in partial shade but will do best in full sun with well-drained soil.
Dahlias should be planted 4-6" deep on their side with an eye facing up. They need a minimum of 8-12" spacing between plants. Larger varieties benefit from additional space. Giving the tubers ample space between plants allows for good air flow which will reduce chances for disease such as powdery mildew and will give you enough room to dig the tubers in the Fall without the risk of accidentally cutting one with your digging tools.
Growing Dahlias
It's best to take a soil test before planting dahlias. Knowing what your soil needs
and how much to add (i.e., fertilizer, amendments) will ensure happy plants and happy well-balanced soil. Contact your local Ag Extension Office for more information on soil testing. Dahlias prefer well-drained, slightly acidic soil with good organic matter. Too much of a good thing can be bad, however. Planting with too much nitrogen can cause an excess of greenery and very few blooms. If your soil is heavy clay or holds standing water, you may want to consider raised beds or planting into pots (5-7 gallon).
Dahlias benefit from staking. They tend to be top heavy and shallow rooted. If growing only a few dahlias, tying them to a bamboo stake as they grow helps keep them upright. If growing in rows, netting or corralling is recommended.
"Pinching" dahlias, by cutting back the plant to the 3rd or 4th leaf set when it is approximately 12-14" tall will encourage branching and produce bushier plants with more stems.
Once plants are growing above the ground, dahlias require deep watering 8-10" deep, at 3-4 times per week for an hour or more, preferably by soaker hose- longer on very hot summer days. Adequate deep watering is required for proper growth and blooming. Most rain showers do not penetrate the soil deep enough for this. Deep watering 3-4 times per week is better than light watering 7 days a week. Hand watering is not recommended.
Harvesting Dahlia Flowers
Once your dahlias begin to bloom, they will continue to bloom until frost. Deadheading spent blooms regularly encourages the plant to produce more blossoms and cutting deep down the stem will encourage additional long strong stems to grow and produce more flowers!
The best time to harvest dahlias is early morning when temperatures are still cool. If kept cool and in clean water changed daily, dahlias will last in the vase for 3-7 days.
Because dahlias originate from Mexico, they have enjoyed and adapted to a warm climate. This makes them an annual in most regions. While they can be grown from seed, most often they are grown from tubers because their seeds rarely produce a genetic replica of the parent plant. Thus, by growing dahlias from tubers you ensure an identical genetic clone of the original parent plant.
Basic Care Tips:
- Dahlia tubers prefer being stored in cool conditions 38-45 degrees Fahrenheit with 75%-85% relative humidity.
- Tubers should be planted in full sun with well-drained soil and good organic matter after after all chance of frost has passed.
- Newly planted dahlia tubers do not need water until they are 6-12" tall in most cases. They need time to root to avoid rot. Patience is key and most Spring soil has enough moisture to help establish new plantings (this varies by climate and local conditions).
- Dahlias benefit from staking the plants as they grow to keep them upright with straight stems.
- Dahlias typically begin to flower 12-16 weeks after planting, until frost.
- As with all cutting varieties, to ensure longest vase life change water daily.
- In late Fall, after a hard frost, dahlias can be cut back to the ground and their tubers dug up to store for subsequent years. If you have done everything right, you will have even more dahlia tubers from your original planting!
Dahlia tubers are much like potatoes. They provide water and energy to the plant early on in life and they have "eyes" just as a potato does. The "eyes" are located at the crown, or shoulder of the tuber. Once planted, shoots will sprout from these "eyes," eventually producing stems that shoot up above ground and grow flower blossoms. The remainder of the tuber helps to create roots while underground. When first receiving your tubers, it may be difficult to locate the eyes. This is because most dahlias need to "wake up" in order to form visible eyes. To "wake up" dahlia tubers, they must be placed in temperatures above 55 degrees Fahrenheit. The time at which it takes for tubers to wake up depends on variety, some taking up to eight weeks to produce their first eyes. One of the joys of growing dahlias is that each year, a grower can become better acquainted with individual varieties, thus with time becoming a better dahlia grower.
Planting Dahlias
Dahlia tubers should be planted in the spring after risk of frost has passed. Once planted they can take 2-8 weeks to sprout. Do not water them until they are 6-12" tall. In doing so early, you run the risk of causing them to rot before they have rooted. They can be grown in partial shade but will do best in full sun with well-drained soil.
Dahlias should be planted 4-6" deep on their side with an eye facing up. They need a minimum of 8-12" spacing between plants. Larger varieties benefit from additional space. Giving the tubers ample space between plants allows for good air flow which will reduce chances for disease such as powdery mildew and will give you enough room to dig the tubers in the Fall without the risk of accidentally cutting one with your digging tools.
Growing Dahlias
It's best to take a soil test before planting dahlias. Knowing what your soil needs
and how much to add (i.e., fertilizer, amendments) will ensure happy plants and happy well-balanced soil. Contact your local Ag Extension Office for more information on soil testing. Dahlias prefer well-drained, slightly acidic soil with good organic matter. Too much of a good thing can be bad, however. Planting with too much nitrogen can cause an excess of greenery and very few blooms. If your soil is heavy clay or holds standing water, you may want to consider raised beds or planting into pots (5-7 gallon).
Dahlias benefit from staking. They tend to be top heavy and shallow rooted. If growing only a few dahlias, tying them to a bamboo stake as they grow helps keep them upright. If growing in rows, netting or corralling is recommended.
"Pinching" dahlias, by cutting back the plant to the 3rd or 4th leaf set when it is approximately 12-14" tall will encourage branching and produce bushier plants with more stems.
Once plants are growing above the ground, dahlias require deep watering 8-10" deep, at 3-4 times per week for an hour or more, preferably by soaker hose- longer on very hot summer days. Adequate deep watering is required for proper growth and blooming. Most rain showers do not penetrate the soil deep enough for this. Deep watering 3-4 times per week is better than light watering 7 days a week. Hand watering is not recommended.
Harvesting Dahlia Flowers
Once your dahlias begin to bloom, they will continue to bloom until frost. Deadheading spent blooms regularly encourages the plant to produce more blossoms and cutting deep down the stem will encourage additional long strong stems to grow and produce more flowers!
The best time to harvest dahlias is early morning when temperatures are still cool. If kept cool and in clean water changed daily, dahlias will last in the vase for 3-7 days.