Growing Dahlias from Seed: A Beginner’s Guide
Dahlias are one of the most popular flowers to grow, and for good reason. They come in almost every color imaginable and in a wide range of shapes and sizes. Many gardeners love them for their versatility in bouquets and their ability to brighten up any garden space.
While most people grow dahlias from tubers (which are similar to bulbs), growing dahlias from seed gives you the unique opportunity to create new and exciting varieties that you won’t find anywhere else. Plus, starting from seed is a more affordable option than buying tubers year after year.
This guide covers everything you need to know about growing dahlias from seed, from germination to transplanting, so you can enjoy these beautiful blooms in your own garden.
Dahlias from seed vs. tubers: What’s the difference?
There are two main ways to grow dahlias: from seed or from tubers (which are similar to bulbs). Here are some key differences to keep in mind:
Key differences
- Genetic variability. Growing from seed can give you dahlia plants that are all different, while tubers will give you clones of the original plant. Planting seeds is a fun way to experiment and possibly discover new colors and flower shapes.
- Cost. Seeds are often cheaper than tubers. You might pay $8 to $35 for a tuber, while a packet of seeds might cost you $5 to $20.
- Time to bloom. Seed-grown dahlias usually take 100 to 120 days to bloom, while tubers might bloom earlier, depending on when you start them.
Advantages of growing from seed
- Novelty and surprise. Every seed-grown dahlia has the potential to be something new and different, which makes gardening more fun.
- Affordability. Growing dahlias from seed is an inexpensive way to grow your dahlia collection.
Sourcing and Selecting Dahlia Seeds
Dahlias grown from seed may not be exactly like their parent plants, but that’s part of the fun. You never know what you’re going to get!
What to look for
Dahlia seeds tend to be thin, black, and less than half an inch in length. To ensure your seeds are viable, it’s best to purchase them from a well-known and trusted grower.
You’ll probably see seeds labeled as either open-pollinated or hybrid. Open-pollinated seeds will produce plants that are very similar to the parent plant. Hybrid seeds may offer some unique and surprising traits.
Recommended varieties and suppliers
If you’re new to growing dahlias from seed, you may want to start with a mix of seeds from a reputable supplier, such as:
- Floret Flowers’ Bee’s Choice Mix
- Johnny’s Selected Seeds’ Giant Hybrid Mix
Kristine Albrech of Santa Cruz Dahlias specializes in hybridizing new dahlia varieties from seed.
When to Plant Dahlia Seeds
Timing is important for starting dahlias from seed. For best results, start seeds indoors about 6 to 8 weeks before the last frost in your area. This gives the seedlings a head start before you transplant them into your garden.
It’s important to consider your local climate and growing zone. Check with your local extension office or gardening resources to get accurate frost dates for your region. This will help you determine the best time to start your seeds.
If you want to sow seeds directly into the ground, wait until the soil temperature reaches 65-70°F.
Step-by-step guide to germinating dahlia seeds
There are a couple of different approaches you can take to get your dahlia seeds to sprout: the paper towel method and direct sowing in seed trays.
Paper towel method
This method lets you keep a close eye on the seeds and make sure they’re getting what they need to germinate.
- Moisten the paper towels. Lay your seeds between two damp paper towels. The towels should be damp, not soaking wet.
- Create a humid environment. Put the paper towels inside a plastic bag or container to help them stay damp. Store the bag or container somewhere warm.
- Keep an eye on germination. Check the seeds every day or so. You should see sprouts within a week. Once the seeds sprout, move them carefully into seed trays.
Direct sowing in seed trays
This method is a little more straightforward and mimics how dahlias might sprout in nature.
- Get the seed trays ready. Fill your seed trays with a seed-starting mix that drains well.
- Sow the seeds. Plant the seeds about ¼ inch deep in the mix. Water the soil gently.
- Give them what they need. Place the trays under grow lights or in a sunny spot. The seeds need consistent moisture and warmth to germinate.
Nurturing Seedlings: From Seed Trays to Larger Containers
Once your dahlia seedlings have sprouted and are starting to grow, you’ll need to move them from their seed trays to larger containers where they’ll have room to develop strong root systems. Here’s how to do it:
Transplanting Seedlings
Wait until the seedlings have developed their “true leaves” — the second set of leaves that emerge after the initial seed leaves. Handle the seedlings gently to avoid damaging their fragile roots.
Choose pots that are big enough for the dahlia seedlings to grow in for a while. A four-inch pot is a good size to start with.
Use a good-quality potting mix that drains well. Avoid using garden soil, which can be too heavy and may contain diseases.
Providing Optimal Growing Conditions
Dahlias need plenty of light to grow strong. If you don’t have a sunny window, use grow lights to provide supplemental light.
Water your dahlia seedlings regularly, but don’t overwater them. Allow the soil to dry out slightly between waterings. You’ll know it’s time to water when the top inch of soil feels dry to the touch.
Feed your dahlia seedlings with a balanced liquid fertilizer every few weeks. This will help them grow strong and healthy.
Transplanting outdoors and ongoing care
Once your dahlia seedlings have developed their first set of true leaves and the danger of frost has passed, it’s time to move them to their permanent home in the garden.
Preparing the garden bed
Before you transplant, it’s important to prep the bed.
Soil preparation
Dahlias do best in soil that drains well. Dig in some compost or other organic matter to enrich the soil and improve drainage.
Sunlight requirements
Dahlias are sun-lovers and need at least six hours of direct sunlight each day.
Spacing
Give your dahlias plenty of room to grow by spacing them 12 to 18 inches apart.
Transplanting seedlings outdoors
Before you put your darlings in the ground, you’ll want to harden them off by gradually getting them used to the outdoor conditions.
Planting depth
When you plant, make sure the top of the root ball is level with the surface of the soil.
Watering
Water the seedlings thoroughly right after transplanting.
Ongoing care
Dahlias need a little TLC to thrive.
Watering
Water regularly, especially when the weather is dry.
Fertilizing
Give your dahlias a boost by fertilizing them every few weeks with a balanced fertilizer.
Pest and disease control
Keep an eye out for pests and diseases, and take action as needed to keep your plants healthy.
Understanding bloom times and seed saving
Growing dahlias from seed can be a little like waiting for Christmas. Here’s what to expect and how to save seeds from your plants.
Bloom expectations
From the time you plant your dahlia seeds, it will likely take about 100 to 120 days before you see the first blooms.
A lot goes into producing those blooms! Sunlight, water, and good soil nutrients can all affect when and how well your plants will flower.
Seed saving
Saving seeds is a great way to get new dahlia plants next year.
To collect the seeds, let the flowers dry right on the plant. Then, gather the seeds from the dried flower heads and store them in a cool, dry place until next spring.
One thing to keep in mind: Because dahlias cross-pollinate so readily, the seeds you save may produce plants with different colors, shapes, or sizes than the parent plant. It’s always a fun surprise to see what you’ll get!
Key Takeaways
Growing dahlias from seed is a fun and economical way to fill your garden with these showstopping blooms. It also gives you the chance to create brand-new, one-of-a-kind varieties that no one else has ever seen before!
Don’t be afraid to experiment with different dahlia types. Try starting them indoors or direct sowing them in your garden. Plant them in different kinds of soil and in areas with varying amounts of light. See what works best for you.
Growing dahlias from seed takes time and patience, but the results are worth it. There’s nothing quite like watching those first little sprouts emerge and then waiting in anticipation for your very own, unique dahlia flowers to appear. With a little care, you’ll soon have a beautiful display of dahlias that you grew yourself, from seed!