Planting dahlia seeds can be an exciting gardening adventure. Unlike planting dahlia tubers, when you plant dahlias from seed, you never know exactly what your plants will look like until they bloom. It’s fun to wait and see that first bloom, revealing what your home grown dahlia hybrid will actually look like.
Dahlias are one of my favorite choices for cut flowers, especially when planting from seed. These stunning blooms offer an incredible variety of colors, shapes, and sizes, making each bouquet unique.
If you want to grow lots of dahlias in your cutting garden, planting them from seed is much less expensive than buying tubers or mature plants. The cost of buying a packet of seeds is usually cheaper than buying just one dahlia tuber.
Dahlia seeds will usually produce flowers that are different from the parent plants, leading to a delightful variety of colors and forms in your garden. This element of surprise adds an exciting layer of discovery to the gardening process, sort of like Christmas morning for some.
What You Need To Know Before Planting
It will take dahlia seeds at least 120-150 days to grow from seed to bloom. This means planting the seeds early, to get blooms before frost.
In colder climates, it’s helpful to start the dahlia seeds indoors, before the last spring frost, to give them a head start on the season. Otherwise your plants may bloom too late and be damaged by fall frosts.
In regions with mild winters, dahlias can be sown directly outdoors in late winter or early spring, as long as the soil is not soggy and temperatures are consistently warm.
For most climates however, starting seeds indoors about 4-8 weeks before the last frost date is recommended.
In this post I’ll be covering planting dahlia seeds indoors.
Materials Needed
Starting dahlia seeds indoors requires a few materials to ensure the seeds have the best environment for germination and early growth. Here’s a list of what you’ll need:
- good quality dahlia flower seeds
- seed starting mix
- vermiculite (optional)
- seedling cell trays, or small pots
- bottom trays
- tape for labeling, with a marker
- a container for bottom watering
- heat mat (optional but preferred)
- grow lights (optional but preferred)
Step By Step Guide To Planting Dahlia Seeds
- Fill your planting container with the soilless seed starting mix.
- Make a little indent in the top of each cell of the seedling tray or container with your finger, into which to drop the seeds.
- Sow the dahlia seeds into the concave space you just created, one seed per hole, and then cover with vermiculite or soil. The seeds should be about 1/4 inch deep.
- Label the container with the seed variety and date. I often place a second label in the bottom tray as well, inside a plastic bag, just in case the first label gets washed off.
- Bottom water the tray until the soil is moistened. Make sure to keep the soil consistently moist until germination occurs.
- Place the tray on the heat mat, which can help warm the soil and help with germination.
- Good quality seeds should germinate within a couple of weeks.
- When 60% of the seeds have germinated, remove from the heat mat and place under grow lights. If you have a bright sunny windowsill, this may work, however grow lights are best for providing the right lighting indoors.
- As the dahlia seedlings grow, they may outgrow their initial containers. If this occurs, transplant them into larger pots to allow adequate room for growth.
- Continue to grow under lights for 14 to 16 hours per day, until the young seedlings can be planted into the garden, after the risk of frost has passed.
- Before planting, the seedlings will first need to be hardened off, to acclimatize the plants to the outdoor setting, and make them sturdier for planting out.
Transplanting Seedlings
- Once the seedlings are fully hardened off, they can be transplanted into the garden.
- Plant into good, fertile well-drained soil with lots of organic matter. Choose a full sun location, for best flowering results.
- When grown for cutting the plants can be spaced fairly close together, at approximately 12 inches (30 cm) apart.
- Water in well after planting.
Maintenance And Care
Pinching
Pinching is a gardening technique that can help dahlia plants produce more stems.
Pinch dahlia seedlings when they have developed at least 3-4 sets of leaves, which typically occurs when they are about 8-12 inches tall. This allows the plant enough foliage to continue photosynthesizing efficiently, while promoting more compact and bushy growth.
Pinch or snip off the growing tip just above the set of leaves beneath it. New growth will typically emerge from these leaf nodes, creating a more branched structure.
Pinching can sometimes be hard to do, but go for it. It’s worth it!
Staking
Once planted outdoors, some taller dahlia varieties may need support as they grow. Install stakes early, and tie the plants loosely, to them to prevent damage from wind or the weight of the flowers.
Dahlias easily tip over from the weight of the flowers, or in a strong wind.
You can also corral the flowers, with rows of stakes positioned on the inside and outside of each row, and with twine running between the stakes to support the flowers.
Post Season Care
At the end of the growing season, depending on what climate you are growing in, you can dig up the dahlia tubers from any seedlings that you want to keep, and store them away for the winter.
During the growing season place a ribbon on the plants that you want to keep, to make sure that you save them.
Wait about a week after the first frost to dig up the tubers, to allow them to cure underground. This process helps toughen them up for storage.
The tubers will likely be fairly small in the first season. Store as you would using any other dahlia storage method.
Using As Cut Flowers
Using your own dahlia seedlings for cut flowers can be very rewarding.
The best time to cut dahlia flowers is in the early morning or late evening if possible, when the temperatures are cooler. This helps ensure the flowers are well-hydrated.
Cut the dahlias when the blooms are fully open but still fresh. Avoid flowers that have already begun to drop their petals, or those with dry or brown areas on the back of the flower head.
Use sharp, clean shears to cut the stems at an angle. This increases the surface area for water uptake, and also prevents the stem from sitting flat at the bottom of the vase, which can interfere with water absorption.
Cut the stems to your desired length, but ensure they are long enough to suit your vase and arrangement style.
Strip the lower leaves off the stems so that no foliage will be below the water line.
Place the cut stems into a bucket of water or holding solution immediately after cutting. Keeping them hydrated from the moment they are cut is crucial for their longevity.
Allow the stems to sit in water for at least an hour or two in a shady and cool location, before arranging them. This process, known as conditioning, helps the flowers hydrate thoroughly and increases their vase life.
Vase life for dahlias can be shorter than for many other cut flowers, with an average vase life of approximately 5 days.
Frequently Asked Questions
Will Dahlias Bloom The First Year From Seed?
Yes, dahlias can bloom in the first year from seed, provided they are started early enough and given proper care.
Seed-grown dahlias might flower a bit later in the season compared to those grown from tubers. Once they start blooming, they can continue to produce flowers from mid to late summer until the first frosts.
What Will Dahlias Grown From Seed Look Like?
When grown from seed your new new dahlia plants can look very different than the parent plant. These are brand new varieties, and new plants.
Dahlias grown from seed will often display the dominant characteristics of the species, which include single blooms, open forms, smaller flowers, and downward facing blooms.
Although perhaps not choice characteristics in the dahlia world, these flowers still look great in flower arrangements.
Can You Plant Dahlia Seeds Straight Into The Ground?
Yes, you can plant dahlia seeds directly into the ground, although this method may present more challenges compared to starting them indoors, especially in cooler climates.
The best choice is to start the seeds early indoors.
Will Dahlias Grown From Seed Produce Tubers?
Yes, dahlias grown from seed will produce tubers during their growing season. These tubers serve as the storage organs that contain nutrients to support the plant through its dormant period, and help it regrow the following year.
These tubers will likely be quite small after the first growing season, and get larger in subsequent years.
Will Dahlias Grown From Seed Come Back Next Year?
Dahlias grown from seed can come back, if the tubers survive the winter, but this depends largely on the climate and how the plants are managed at the end of the growing season.
Dahlias are perennial in terms of their root structure (tubers), but are treated as annuals in climates where the ground freezes.
In cooler climates dahlias will not survive the winter if left in the ground, however you can dig up the tubers and store them for the winter.
Conclusion
Growing your own dahlias from seeds and using them as cut flowers can be a rewarding experience.
I hope this guide inspires you to plant, nurture, and enjoy these beautiful flowers in your own garden.
Remember, each bloom you grow not only adds beauty to your surroundings, but also deepens your connection with nature.
Happy gardening, and enjoy your own home grown dahlias this season!
Please leave a comment below with your questions or experience with planting dahlia seeds. I would love to hear about your new dahlia hybrids!
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